Lecture: Refraction: A Step Up From the Basics

This lecture will focus on clinical pearls beyond the basics of refraction. Specific tips will be offered for troubleshooting common difficulties encountered during refraction.

Lecturer: Dr. Diane Russo, OD, MPH, FAAO, New England College of Optometry, Boston, USA


DR RUSSO: All right. Good morning, everyone. I’m just gonna share my screen here. So this is going to be a follow-up to my previous lecture, so I’m Dr. Diane Russo, I’m an associate professor at the New England College of Optometry, and the first webinar that I did on this topic was sort of the basics of refraction, working our way through the procedure step by step, and of course that’s if the procedure goes according to plan, which most of the time it does not. There are usually some small modifications that we need to make, based on patient interaction, and how the steps are going through the procedure, and so this presentation was meant to be very practical, based on many of the common experiences that I have in practice, myself, when I’m refracting, and then also things that I have seen students have difficulty with over the years, while I’ve been teaching. Because I’ve taught this procedure in the lab setting. And that’s where we more so focus on the step-by-step process in making sure everything goes according to plan. But then when I’m working with students in clinic, that’s where very often the content of this lecture comes in. So when things aren’t going exactly the way we’ve taught, in that step by step process, what are the different things we can do to modify the procedure, so that we can come up with the same conclusion that we need to get to? And so today we’ll be very briefly just reviewing the steps that I went over last time, just so that we’re all on the same page, in case anyone on this webinar has not seen the previous lecture. And then we’ll spend the majority of the time going through some of the tips that I’ve put together for very common challenges, or issues that may come up during the procedure, and ways to troubleshoot that. And then at the end, and maybe a little bit throughout, we’ll talk about patient communication, and how important that can be, and ways that you may need to modify the technique, just based on how you’re communicating with your patient. So again, this is part of that brief review from the last lecture. But the goal of subjective refraction is that you want to come up with a glasses prescription that the patient can see through, so that piece is speaking to the visual acuity. Making sure the visual acuity is optimized. But that the patient can see through comfortably. So that’s that other portion. And we’ll touch on that a bit today. The same thing in the last lecture. We went through the different parts of the phoropter, to make sure that we’re all familiar with the different knobs and dials. Because we will be discussing some of those today as well. And then this was the layout that we went through, the process that we went through, in the previous lecture. So I wanted to make sure that this terminology would be familiar. The initial sphere check, the cylinder, axis, and power refinement, the second sphere check. So those are what we will predominantly focus on today. Really the initial sphere check and then the cylinder refinement steps. But I wanted to make sure that we had these steps outlined, and that we would be using the same terminology, throughout the rest of this presentation. So when you are starting your refraction, there are four common starting points. So the first two are preferable. The third you could go with if you don’t have any other information. And then sometimes you have no information. So retinoscopy and autorefraction, depending on what type of equipment you have available, are usually most helpful, because they’re an objective measurement of your patient’s refractive status. Lensometry can be another helpful piece of information, but that is not necessarily based on the patient’s current refractive status, and that can be misleading at times, depending on where the patient received their glasses. I have a number of patients that come in, that are not wearing their own glasses. They may be wearing a friend or a family member’s glasses, because maybe the prescription is close, and it improves their vision better than not wearing any prescription, and so they wear them, but if you don’t know that, and you check the lensometry, and then you’re working off of that prescription, you could be starting the process with inaccurate measurements. And so you should be careful, if you’re using lensometry, and maybe ask the patient: Are these your glasses? Where did you get them? How long have you been wearing them? So that you can get a sense of how much you can rely on that prescription to work off of, for your subjective refraction. And then certainly there will be times where you have no information. If you don’t have equipment at your disposal, to get an objective measurement of the patient’s refractive state, so you don’t have a retinoscope, and you don’t have an autorefractor, the patient doesn’t come in with any glasses, so you’re sort of starting from scratch — so these are the four, I think, most common starting points that I’ve interacted with in my clinical experience. And we’ll talk a little bit about how to manage starting from each of those points. But before you do any of that, before you start the subjective refraction process, it’s advisable to check the patient’s habitual distance visual acuity. So if they come in with glasses that are theirs, it’s beneficial to check their vision through those glasses. If not, you’re just checking them without any glasses. And depending on what that vision is, you may then go to the next step, by using pinhole acuity. And so you can see here I have this — this is an occluder with the pinholes that slide down over the open ocular, and this is me, pinholing myself. And you can see here there are multiple pinholes. And in clinical practice, I have found this to be an easier pinhole occluder for the patients to use. I have a note down here: This can be difficult for some patients. Having the multiple pinhole openings makes it a little bit easier when the patient is trying to use the occluder in front of their eye. There are some occluders with just one pinhole in the center of the occluder, and that can be more difficult, because the patient has to adjust it, just so, so that they’re able to see through that one pinhole. And the reason that we’re doing this is to get an idea, a general sense, of what the patient’s best corrected visual acuity could be. And so generally we say: If the patient’s entering visual acuity is worse than 20/30, you may want to consider pinholing. So this takes a little bit more time in the beginning of the exam. But the intention is that if you know what the patient’s pinhole acuity is, then you have an idea of what endpoint you’re trying to get to, at the end of your subjective refraction. And so what are some of the outcomes of the pinhole acuity? The first is the acuity could improve. Again, this is giving you a sense of what the best corrected visual acuity could be. So if the pinhole acuity improves, then you know that there’s at least some portion of the reduction in vision that is attributed to uncorrected refractive error. So that their vision should improve to around what that pinhole acuity was. Just by giving a spectacle correction. The second thing that could happen is the acuity could stay the same. So assuming that the patient is able to do the procedure, it could be that there is an ocular disease, probably more specifically something going on in the macula, that is stopping the acuity from improving. And then the third thing that could happen is that the acuity could actually worsen. And so this could indicate that there is an ocular disease in the macula, or that the patient is eccentrically viewing. So they’re not using the center of their macula, the fovea. And in this case, the pinhole acuity is not going to be very helpful for you. So we have our first question here. And this is based on what we just talked about with the pinhole acuity. So if a patient’s entering habitual visual acuity is 20/50, and you pinhole, and the pinhole acuity is 20/25, what is the most likely best corrected visual acuity? And again, thinking about this as in the neighborhood. It may not be exact. But using the pinhole acuity, you’re able to get a sense of what the patient’s best corrected vision could be. All right, excellent. So it looks like the majority of you put 20/25. And that’s what I would have put. That’s the answer that I gave here. But it looks like the second most common answer was 20/30, and that could also be correct. Remember, we’re looking for an approximate best corrected visual acuity. So usually we’re looking at whatever the pinhole acuity is, as the best corrected — the potential best corrected visual acuity. But sometimes it could be a little less than that. So 20/25 is the most likely here. But 20/30 may also be possible. 20/40 or 20/50 is less likely. You should expect the patient’s vision to improve better than the 20/40 and 20/50. So now that we’ve done our pinhole acuity, after entering visual acuity, we’ll have a sense of what the patient’s best corrected vision is, and just to go back for a moment, in this example, if the patient’s best corrected — if the patient’s pinhole acuity did not improve, so the entering acuity was 20/50, and the pinhole acuity was 20/50, then we should be suspecting that there could be an ocular disease that’s causing the reduction in vision. And so we shouldn’t be spending a lot of time on the subjective refraction for this eye, trying to get it much better than 20/50. We’ll try, obviously. We go through the steps, like we normally would. We try and sort of push the best corrected visual acuity. But again, this is giving us a sense of what our potential endpoint is, so that we don’t spend a lot of time trying to improve the acuity to 20/20 if the pinhole acuity didn’t improve past 20/50. So now if we’re moving into our first step of the subjective refraction, so our initial sphere check, so we’ll show the patient the Snellen chart, and ask the patient: What’s the lowest line you can read? So your directions for getting the initial acuity with the initial sphere check depends on the type of chart that you have. So if you have one chart that you just put up on a wall, something like what’s in the presentation here, you can ask: What’s the lowest line you can read? If you have a chart where you can isolate a line, you can just put up, let’s say, a 20/40 line, or 20/50 line, or something around what the patient’s entering acuity was, or even maybe a little bit smaller. So your directions will depend on the type of chart that you’re using. And the ability to isolate a line or letter. And so from the last presentation, we mentioned going in quarter diopter steps for the initial sphere check. But now we’re thinking about troubleshooting, so if we’re starting by using retinoscopy or autorefraction results, or even lensometry, you could start with the quarter diopter steps. But if the patient’s visual acuity is fairly reduced, let’s say their vision is 20/70, or 20/80, then you may want to go in half diopter steps, depending on if you think you need to go in the minus or the plus direction. So it doesn’t necessarily have to be exactly in quarter diopter steps. Sometimes it’s easier for the patient to notice a difference, if you go in larger steps. So you can try a -50. Or a +50, again, depending on what the patient’s refractive error is, that you know of at the time. If the vision is very reduced, you could even go in 1 diopter steps. So again, this is all based on what the patient’s acuity is, and what you think it’s going to improve to. So if the patient’s entering acuity, based on whatever starting point you’re using, is more reduced, then you may want to use larger diopteric steps. If it’s 20/30, then you probably want to use quarter diopter steps. And that will help you go through the procedure quicker, but it will also help the patient to decide what’s making a difference. If their vision is very blurry, a quarter diopter — if someone’s vision is 20/200, a quarter diopter step is probably not going to make much of a difference to them. If you show them a half diopter or diopter step, it should be much more noticeable. And so then it should be easier for them to respond to the questions that you’re asking. You know, which is better, or what’s the lowest line that you can read. If you’re making a quarter diopter step, they’re probably going to say it looks the same. If you’re starting from scratch, like I said before, so you don’t have any other objective information, you don’t have a retinoscope handy, you don’t have an autorefractor, the patient doesn’t have glasses, here you would probably want to start with larger steps to begin with. But the important piece that you want to take into account is the initial vision of the patient and their age. So, for example, if you have a 25-year-old patient, and you’re checking their vision in their right eye, their distance acuity is 20/100. This is uncorrected. Their uncorrected distance acuity is 20/100, but their near acuity is 20/30, here you should be considering myopia. Because the distance visual acuity is reduced, but the near is better. And so you may want to start with a -1. You could start with -0.50, but on the next slide, we’ll talk about what diopteric value you should be expecting, but here you can start with -1, and check the patient’s acuity and see how much it improves. Another example. Now say the patient is 55, and their uncorrected distance visual acuity is 20/70, and their near visual acuity is 20/60. So now the distance and the near are both reduced. Our patient here is older. So we may want to consider hyperopia. And/or presbyopia. And so you may want to start with +.50 steps. So these are just general guidelines, again. This isn’t a hard and fast rule. You could also be — this patient could also be a myope. And have presbyopia. And that could be why both the distance and the near are reduced. But you want to be taking both into account. The distance acuity and the near. And the patient’s age. Because depending on the patient’s age, whether or not they’re presbyopic will impact what their near acuity is. And then you take that into account, when thinking about what their distance refractive error could be. And so this chart I find to be helpful, because the other question becomes: Well, how does astigmatism fit in? What if someone — in the previous examples, we were talking just about myopia or just about hyperopia, but what if the patient has myopia and astigmatism, or hyperopia and astigmatism? So here, our first patient, we said their entering acuity was around 20/100 at distance. I said we could go in -1 steps, because if we’re expecting their acuity to be around a -2, based on this chart, so this is 20/120, whereas in our example it was 20/100, we’re expecting the patient to be around a -2 diopter myope. There could also be some cylinder, and that will also skew the visual acuity. So maybe they’re really a -1.50 myope, and a -1 cyl. But this chart I find to be helpful in thinking about — when you’re thinking about the reduction in visual acuity, and what the potential refractive error could be, if there is a match or a mismatch. One of the most common things I talk about with students, when we’re going over the physical exam data, while in clinic, is: Does the prescription that you came up with make sense? Does it make sense, based on the patient’s entering acuity? Their chief complaint? Their age? Their objective findings? So whether we have retinoscopy or autorefraction, and then followed by the subjective refraction. So very often, for example, I’ll have students come in. The patient’s entering acuity may have been, let’s say, 20/40. And their final refraction comes out to be -1.50, -.50, axis 1.80, say, for example. Now, that doesn’t make sense. If their entering acuity was 20/40 — this should be a 20, instead of 40/40, sorry. Then they should be around a -0.75 diopter myope. But the student may have gotten a lot more minus. So in that case, the student was overminusing the patient. So I find this table very helpful to come back to periodically, when thinking about entering acuity, and if that makes sense with the refractive findings that you’re coming up with. These are some tips from the last presentation. So when you’re starting the refractive process, when you’re showing the patient, let’s say, a portion of the chart, maybe you don’t have the whole thing open, but you’re just showing maybe three or four lines, if the patient is not able to read the top line, just go up to the larger letter size. And this may be more helpful when you’re checking entering acuity. Because at that point, you don’t know what the patient’s acuity is, as opposed to when you’re starting refraction. Because at that point, you should have a better sense of what the patient’s entering acuity is. Isolating lines and letters can be incredibly helpful. Especially if the patient is reading a line. If they’re getting all the letters wrong, it can be difficult to figure out where the patient is. So the isolating lines and then letters can be very helpful for you and for the patient. And if you’re showing the patient more and more diopteric value, whether it be more plus or more minus — in all likelihood, more minus — but their vision is not improving, then you want to reduce the power to when they first were able to read the lowest line that they were able to read, if that makes sense. So from the previous presentation, I had given an example: If someone is reading 20/30, and they’re initially at a -1, and you give them -1.25, they’re still reading 20/30. 1.50, 20/30. 1.75, 20/30. You’re giving them all this minus, but it’s not improving their acuity at all. You should go back down to -1 and move to your cylinder check at that point. So that’s where we are. We’ve gone through the initial sphere check. Now we’re ready to do our cylinder refinement. We start with the cylinder axis, and isolate one line above the best visual acuity that they obtained during the initial sphere check. You insert the JCC and give your directions. You tell the patient: I’m going to give you two views. You tell me which is clearer, or if they look about the same. I always include that in my directions. So when we’re talking about the cylindrical refinement, it’s the axis and the power pieces. So I’ll go through some of the challenges that you may encounter and need to troubleshoot when you’re doing the axis refinement and then the power refinement. There are similarities between the two, and they can be handled similarly as well. So the first is: When we’re talking about the axis refinement, if the patient is giving inconsistent choices. Let’s say you’re showing them axis 180, giving them the two choices, they choose 1, and they go back and forth between axis 180 and 165, for example. So what do you do? They clearly are not demonstrating a preference for one or the other. You want to make sure you get it right. Just pick one at this point. You just pick one and then move on to the sphere refinement, the power refinement. You could pick one — depending on how large of an axis range we’re talking about, so for the example of the 180 and 165, you can choose 180, you can choose 165, you can choose something in between, but the tip down here — this is the most important piece to remember — the higher the cylinder power, the more precise the axis determination needs to be. So, for example, if the patient has 3 diopters of cylinder, then you can’t just pick one. You do really need the patient to guide you in which direction they have a preference. In all likelihood, the patient will be much more sensitive to axis changes with higher amounts of cylinder. With lower amounts of cylinder, let’s say half a diopter or even one diopter, that’s where the patient may not be as sensitive. And so if you’re within a range, you could pick something just in between. So in our example here, I said our patient is going back and forth between 180 and 165. Choose 170 or 175, and then move on to the power check. So here’s our second question. So during our cylinder axis refinement, which we just talked about, the patient keeps going back and forth between axis 80 and axis 85. So we’re talking about a 5-degree difference. So which axis should you choose, before moving on to the power refinement? This is a little bit different from our last question, because we added about 15 degrees that we were working with. This is a little bit of a trick question, because really only one of these answers, I would say, is a little bit off. So most of you said 83, and that’s exactly in line with what I was just saying, where you could choose something in between and then move on. However, we’re only talking about 5 degrees here. 80 or 85. So you could have chosen any of these. You could have put it at 80, 83, or 85. Really the only option here that doesn’t quite make sense is to put it at 90. Clearly the patient is preferring between 80 and 85. So to put it at 90 would not make sense. But to put it at 80, 83, or 85 are all possible options. If we’re still on our axis refinement, but the patient, let’s say, is consistently choosing the same number, so we ask them: One or two? One. Three or four? Three. One or two? One. Three or four? Three. So they’re always choosing the same option. And if you don’t use three or four, one or two… Is it better? And the patient says one. One or two? The patient chooses one. So what you may need to do — certainly you can just change your choices. Because you know what you’re showing the patient as one versus two, and if they’re always choosing one, then you can just give them the opposite choice, and see if they still choose one. But one of the things you can also do — because sometimes it’s the choosing a number in the patient instructions that can be difficult for the patient. And so in that case, you may want to change your directions. So instead of asking which is better, one or two, you can say: Is it better here? Or here? And this can get a little confusing. So you do have to be careful with this. Because you’re calling both choices “here”. But some common responses that the patient will say if you ask… “Is it better here or here?” The patient may say “this one”, and they mean the second choice, or “the other one”, and they mean the first choice. Or you may also say: I’m going to give you one option. Here’s one option. Get a sense of how this looks. Take a look at all the letters on the line. And now I’m going to show you another option. Is this one better or worse? So they’re comparing the two again, but you’re sort of using number one as the reference, giving them time to really get a sense of how things are looking through that view. And then switch to the second one, and ask: Is the second better or worse, compared to the first? This takes a little bit more time. This third option here. So you do want to keep that in mind, depending on how much time the procedure is taking. And how decisive or indecisive the patient is being during the procedure. Always — this tip applies for both the axis and power refinement — always consider adding this piece to your explanation. Telling the patient: Both views may be blurry, and that’s okay. But between these two views, is one better than the other? Or do they look about the same? Because sometimes patients may not want to answer, or may not understand exactly how to answer, because they both look blurry to them, and they’re thinking… Well, neither is better. They’re both blurry. So if you tell the patient ahead of time both may be blurry, but is one better than the other, or are they about the same, that can help in giving some context and explanation to the patient about what to expect. And then finally, for axis refinement, sometimes the patient may just be giving you consistent choices that keep rotating the axis wheel. So they’re just taking you around and around. They’re not clearly preferring one axis, or even one small range of axis. And this is something I’ve noticed my students in clinic losing a lot of time on. Because they’re letting the patient take them round and round, and you lose a lot of time in that case. So if this is happening, what it’s indicating, in all likelihood, is that the patient is not very sensitive to axis changes. So what you can do is just pick one axis, and move on to the power refinement. How do you choose one? If the patient has no preference between 0 and 180, take into consideration the objective information you have, from either retinoscopy or autorefraction, or previous lensometry information. So, for example, if the retinoscopy indicated the axis was 180, choose 180 or something close to it, and then move on to the power refinement. You may need to go back to the axis at some point in time, but this is so you can continue moving forward with the process, with the procedure, so you don’t get bogged down and lose a lot of time on this piece. Because this is probably indicating that the patient is not sensitive to axis changes. You could also ask the patient just to rotate the axis wheel on their own. So from behind the phoropter, the patient just sort of reaches there, and rotates it around, say — okay. You can place their hand on the axis wheel. Say okay, rotate this around, and stop where it looks clearest. This is not something I do on a very regular basis, but it is definitely something I have done, depending on the patient’s responses, and how sensitive they are to axis changes and blur associated with those axis changes. So now if we move on to the power refinement, you’ll notice that the first two common challenges are the same as what I talked about with the axis. And then the third is a little different. So again, the patient is being sort of inconsistent. Maybe going back and forth with a couple different choices. So the patient’s choosing the white dots, and then they’re choosing the red dots. Again, just pick one and move on to the second sphere check. So if our patient during the cylinder power refinement keeps going back and forth between -1.25 and -1, which power should you choose? All right. So 89% of you said -1. Great. And 8% of you said -1.25. The vast majority said -1 or -1.25. I agree. Either one of those choices could work. Some of you said -0.75. It’s not that that’s necessarily incorrect, but if the patient is clearly preferring -1 and -1.25, -0.75 is a little bit outside that range, so it’s a little bit too low. -1 is the most common response here. Usually if the patient is choosing between two powers, the more conservative thing to do is to choose the lower power, so we’re not giving them a higher prescription than necessary. So you can, again, just pick the -1, and then move on to the second sphere check, and you can always further refine whether they need the -1 or -1.25, after you’ve removed the JCC. Great. So again, similar to the axis refinement, if the patient keeps consistently choosing the same number, you as the examiner could just change what you call number one and what you call number two. To see if the patient is consistent, or can become consistent in their responses. But one of the other things that you can do is just change your direction. So again, instead of saying: Is it better, one or two? You can say is it better here or here? Again, the patient may say this one or the other one, and that’s how they would indicate. So instead of having to choose between the two numbers, they’re still comparing the two views. It’s a subtle difference, but some patients respond to that set of directions better than others. And the third thing you can say: Here is one option. Get a sense of how this looks. Take a look at all the different letters on the line. Now I’m going to show you another option. Is this one better or worse? And again, this is the third type of direction that you can give that would probably take a little bit longer. But again, this is something that you can choose, based on how your patient is responding to your directions. So the third option that’s a little bit more unique to the power refinement is that the patient keeps choosing more minus power. So they say: Here’s one option. I want this one. You increase the cyl, they still want the red dots. Again, they want this option. Again, they want this option. So as you’re going through, step by step, they keep saying that they want more cylinder power. More power, more power, more power. Do you keep giving it to them? That’s the question. So maybe or maybe not. It depends. So you do want to consider what your previous information is. That you may be working off of. So what were the retinoscopy findings? What were the autorefraction, what was the lensometry? How much cylinder was found on the objective testing? There shouldn’t necessarily be a big disconnect between the objective findings and the subjective findings. So then you have to question: Why are they demonstrating such a preference for the increase in power? Is there an issue with the sphere refinement to begin with? Is there an issue with the axis determination? And does the patient really need all the minus that they seem to be preferring? And then also you want to consider the patient’s vision. Their visual acuity, from the initial sphere check. So the better the initial sphere check, the smaller the adjustments that you most likely needed to make on the cylinder refinement. And then choose a power based on that information. So if after the initial sphere check the patient’s vision is 20/30, and you’re going in, and the patient keeps wanting more and more and more minus, and it’s much more than what they previously preferred, then you have to question: I don’t think that they really need all of this, because if their vision was already 20/30 to start, we probably don’t need to add multiple diopters of cylinder correction in order to improve their vision to 20/20. So one of the things that you can do here is take out the JCC altogether, don’t give them those choices, one or two, anymore. And then show them some of the options, without the JCC. So if a patient is choosing, let’s say, up to 2 diopters of cylinder, and maybe they started with 1 diopter, what you can do is now, after removing the JCC, just show them the -1 cylinder power, and you can even check their acuity at this point, or just ask them, showing the same line that you’ve been showing them, how does it look here with the -1? And then switch and show them with the -2. Do they notice any difference? And then go based off of those responses. Again, the choices that you give them should be based on the combination of your objective measurements, plus the patient’s visual acuity after the initial sphere check. So here’s our last question. And so if you’re going through this process, after the initial sphere check, this is the refractive finding that you get. And the patient’s acuity is 20/30. So during the cylinder power check, the patient keeps choosing that minus. More minus, more minus, more minus. And you get up to this power. The -2.50. So you decide to remove the JCC. And proceed with the testing from there. So what power should you show the patient first? Which cylindrical power should you show the patient to start with? So we know that with the -0.50 cylinder power, their acuity was 20/30. So we’re probably going to need some additional cylindrical correction. So where might you start? All right. So the majority of you said -1. Great. That is what I would have said as well. So you can notice that with a lot of the questions that I’ve been asking, sometimes I’ll give one answer as what I would recommend, and other times, there are multiple choices. So here this is one of the examples where I would probably start with the -1. Some of you could have started with, say, -0.75. That would have been perfectly fine as well. I think the larger point to take home from this question is to start with the lower power. Because in this case, we should be suspecting that the patient does not need a significant amount of cylindrical correction, beyond what we’re already finding. And so if you were to start with -1.50 or -2, you’re probably already starting with a higher cylindrical power than the patient truly needs. And so you could start with… You can even start with a -50 and build up from there. But I probably, myself, would not start higher than the -1 at this point in the process. So that’s if the patient keeps choosing that they want the cylinder. What happens if the patient kicks out all the cyl? So they reject all the cyl during the process. And now this is reducing their vision. This is making their vision blurrier. So now that’s probably telling you that they do need the correction, but they’re not choosing it. Sometimes just with the JCC, and the choices between those two, the patients give answers that don’t match what they truly need. So in this case, again, I’ll just remove the JCC, and show them the cylindrical changes, just by looking at the chart. And not giving them the choices of the 1 and 2 through the JCC. So if I found 1 diopter of cyl on retinoscopy, and they kicked all of that out, during the sphere, the cylindrical refinement, the power refinement, I would then show them the chart again, remove the JCC, and show them with and without the -1. Because I think they’re gonna need around a -1 correction, so I will take out the JCC, and show them the difference, and sometimes removing the JCC sort of simplifies the choices a bit more for the patient, and then you can go based on their responses. If you don’t find any cyl, objectively, but you think that the patient may need some correction for astigmatism, you can do a cyl check. So you insert the JCC with the in power orientation. So our dots are lined up with the axis wheel. And start with the axis at 180. And you ask the patient: Do you prefer this one or this one? So one or two. And if they choose the white dots, then you rotate the axis to 135. So you’re sort of checking the major meridians. And you give them the same choices. Is it better three or four? And let’s say they choose four. So they’re rejecting the cylinder power. You would then move your axis to 90, give them the same choices. If they reject the cyl again, by choosing the white dots in the 90-degree orientation, then you would rotate the axis again to 45. So this is to check all the major meridians, to see if the patient does demonstrate a preference for cylinder in any of those axes, in any of those orientations. Let’s say — so in the example I just gave, the patient rejected — so they chose the white dots in each of those orientations. And let’s say the patient does demonstrate a preference for cylinder. You show them the choices at axis 135. You show them the red dots and then the white dots. So choice one and choice two. And let’s say they choose one, they choose the red dots here. And so that means that they do want the cylindrical correction here. And so what you would do is now switch the JCC to an axis orientation. And add half a diopter of cylindrical power. One tip here, which we don’t have a lot of time to get into the spherical equivalent, but you do want to make sure that throughout the procedure you are keeping the spherical equivalent. Which means: For every half a diopter of astigmatic correction that you change, so in this case, we added half a diopter of cylinder, and we have to add plus a quarter to the sphere. So we’re keeping the spherical equivalent here. And then you would just move through the rest of the procedure, like you normally do, with your axis and cylinder refinement. If you’re having difficulty during the refraction, let’s say the patient’s responses are not very decisive, or they’re giving you, again, those inconsistent choices, and you’re doing the best that you can to troubleshoot, but you’re still not feeling very confident, by the end of the procedure, it’s always a good idea to then trial frame. So put what you think you might prescribe into the trial frame, and make some changes from there. To simulate a more real world situation. Take the patient out from behind the phoropter, and show them what you’re thinking of prescribing in the trial frame. The last thing that we’ll cover for the last few minutes is the patient’s cues that they may be giving you, during subjective refraction, and how to adapt your technique and your directions, based on that. So this takes a little bit more time. This is sort of the intuitive nature of the procedure. This is where sort of the art and the science mix, much more, so for example: If you have a patient that’s very uncertain, when they’re making choices, and this can happen during the sphere refinement, but even during the cylinder refinement as well. So here you may want to reassure the patient that both choices may be blurry, and that’s okay. Is there one that’s better than the other? Or are they the same? Because the patient could be hesitating, since they’re not sure which option to choose, since they both look bad to the patient. And you can say: They may be equally bad, and that’s okay. That’s still information that I can use to then proceed through the rest of the procedure. And you may need to change your directions, or reassure the patient. It’s okay if they’re both bad. We’re going to continue the procedure from there. Some patients can be very hesitant, because they don’t want to make the wrong choice. They’re worried that that will throw you off, and they’ll end up with the wrong prescription. Some patients will have a significant sensitivity to blur, and others will not be sensitive at all. The ones that are not sensitive at all — we don’t have to worry quite so much about, because they have an increased tolerance for blur. So even if things are not exactly to the 5-degree axis, exactly right, the patients can tolerate it. But for patients that are very sensitive to blur, and you can tell, because every time you may make a small adjustment during the procedure, they’ll know exactly. They’ll respond to it. Oh, no, you change the axis 5 degrees, and it’s — oh, no, it’s very blurry now. So you can tell, if you’re making the smallest possible adjustment, if the patient is able to notice that change, they’re very sensitive to blur. So you have to be very careful, as you’re going through the refraction, step by step, to be very careful, getting the patient’s feedback. Make quarter diopter steps, definitely no greater than 15-degree axis changes, and ask questions as you go along, and explain to the patient what you’re doing. I’m just going to rotate this a little bit, and tell me if you notice any difference. I’m gonna change this lens a very small amount, and you let me know if it gets any better or worse. Again, these may take a little bit longer, but you do have to be aware of patients that are very sensitive to blur. If a patient is very hesitant to read the smaller letters, let’s say they read the 20/30 line, but then when you go to 20/25, they’re very hesitant, maybe they’re very, very slow, they’ll read some of them, and then you go down to the 20/20 line, and they stop reading. And so it could be that all the letters are too small. But it could be that they don’t want to get it wrong, and so they’d rather not read the line at all than guess, and in this case, I encourage my patients. Can you read any of the letters on this line? It’s okay to guess. Take your best guess. Give it your best shot. Encourage the patient. I notice a lot of times, when I’m working with my students, they’ll say: This is what the patient’s best vision is. And then I’ll come in, and encourage them in that way. It’s okay to guess. Give it your best guess. Try. Isolate the line, isolate letters. And then more often than not, the patients will be able to read more of the letters than they think. And some of this can be that they don’t want to guess. They don’t want to get it wrong. And so if you’re telling them that it’s okay to guess, it gives them that permission to try, and then you take that into account, when making your refractive decisions. And then lastly here, sometimes patients will give very descriptive responses. So instead of clearly saying: I prefer one or I prefer two, the patient may say: You know, one looks shorter and wider. But two looks taller and thinner. And so I as the examiner don’t exactly know what to do with that information. So I will just ask: Is shorter and wider better? Or is taller and thinner better? If you had to choose one of these, which one would you choose? Because from their description, I don’t know which they prefer. Or which they consider better. So I will just directly ask: Do you think that this is better? Or do you think that this is better? And so trying to, again, adjust your directions to clarify what the patient really means, with the responses that they’re giving. And this should then help you make your decisions, going through that step by step refractive process. Above all else, the most important thing is to be patient. During the technique, encourage the patients. Tell them it’s okay to guess. Let’s try a smaller line. And try to simplify your directions as much as you can. Try not to assume anything. It goes back to that last point. If the patient’s describing what they’re seeing, don’t assume that the smaller or the shorter and wider is better. Because that may not be better, in the patient’s view. So being as simple as you can with the instructions, but asking clarifying questions, and adapting your instructions, as you go along, can help avoid a misunderstanding in the long run. And that is it! So thank you very much. And I will take some questions.

>> Great. Thank you, Dr. Russo. We have about ten questions so far. Do you want to open up Q and A?

DR RUSSO: Okay. All right, so… So the first question is: What is your preferred cylinder refraction, plus or minus cyl, and why? So this is a great question. So in every setting I’ve ever worked in, I have worked with minus cyl, and that’s the way I was taught in school. My understanding, if I wipe out some of the cobwebs, is that… I believe it had something to do with controlling accommodation. But I would have to fact check myself on that. So my preference is for minus cyl, but that is purely from a familiarity standpoint, because I’ve never worked with plus cyl. Some of the ophthalmology clinics that I have colleagues and students that work in use plus cyl. So my preference, again, would be for minus. But that’s because I’ve only ever worked in minus cyl. At the end of the subjective refraction, during binocular equilibrium, can one balance the power of the cylinders before the equilibrium of the spheres? So I think this question is asking: During binocular balance, so once you’ve gone through your initial sphere check, the cylinder, axis, and power refinement, second sphere check, maybe, and then the plus/minus 0.50 checks, then you may do binocular balance? So typically, when you’re binocular balancing, you’re not specifically balancing the cylindrical power. At that point, the entire procedure is just focused on the sphere power. So everything according to the cylinder should have been done during the axis and power refinement, and then you don’t really touch the cylinder again, unless you’re doing one of those troubleshooting things I talked about, where you remove the JCC, and make some modifications there. But when you’re doing the binocular balance, you’re only making adjustments to the sphere at that point. The question is: How accurate is it to use pinhole glasses? I’m not entirely sure of exactly what the question is asking, as far as accuracy. If that means… How accurate is it in correlating with the best corrected vision? I can’t say definitively, beyond what I explained in the beginning of the lecture, which is: It’s giving you an estimate of what your best corrected vision should be. And so it may not be exact. So if your pinhole is 20/25, but you’re only able to get the patient to 20/30, that happens very commonly, so it won’t be exact, but I think the pinhole acuity is best used in thinking about it holistically. So is the patient’s acuity improving? Is it staying the same? Or is it getting worse? And that’s really meant to help you figure out: Do you think that there is some kind of pathological reason for the reduction in vision? Or do we think it’s related to uncorrected refractive error? The next question is: How does the AC/A ratio work to our advantage in subjective refraction? So I’m not entirely sure what you mean by work to our advantage in subjective refraction. So I think the first thing is: You need to have a reliable subjective refraction first. Before you move on to any AC/A testing, or any binocular testing. Because if your subjective refraction, or the prescription that you’re working off of, is skewed, then that could impact the rest of the data that you’re gathering. Because it’s affecting the binocular and the accommodative system. So you would need to have your subjective refraction done first, before you move on to AC/A ratio. And conducting an AC/A ratio is for a separate set of reasons, usually. That’s more associated with binocular and accommodative testing, to see perhaps if that correlates with the patient’s symptoms, if you’re thinking about vision therapy, or prescribing prism. So does the pinhole always give the algebraic value of the bearing sphere? This goes back to a similar question. It may not be exact, again. The same example I gave before. If the pinhole acuity is 20/25, that’s an estimate. So if the patient’s best corrected acuity is 20/30, it’s relatively close. And that’s okay. But it may not be exact. So I think what you want to get a sense of is: Is the entering visual acuity improving? Does the pinhole improve the acuity or not? And then take that into consideration. But it may not be exact. There sometimes can be a mismatch. But it shouldn’t be a very big difference. So if the patient’s pinhole acuity is 20/25, and you’re only able to get them to 20/50, something’s not making sense there. With the spectacle correction, it should improve better than that. Maybe not exactly the 20/25, but fairly close. So again, it’s taking that into consideration. What is the VA for patients who can read only part of successive lines? So the rule that I typically use is: If they get half the letters on the line correct, then they get credit for that line. So if there are even six letters on a line, if they get three of them, then they get credit for that line. If there’s five, five letters on a line, again, if they get three, then they get credit for that. If they only get two, then they don’t. If they get three letters on the 20/25 line correct, it will be 20/25, maybe -2. If they only get two letters right on the 20/25 line, then I would record that as 20/30, +2. Can astigmatic fan help to refine cylinder axis in case of indecision? Yes, absolutely. For the purpose and the scope of this lecture, based on the amount of time we had, I did not cover the fan start. There’s also stenopaeic slit. There are a few techniques you can use. If you have that as an option for where you are, I would suggest using that. Some patients have very different axis from the autorefractor. Like 50 on autorefractor and 120 on subjective refraction. Why is this? Some patients also have different axis between their old spectacles and their current. Why is this? Yes, I have found that quite a bit in practice as well. I don’t have an exact answer as to the why. I mean, part of that is: The reason why we don’t just use what’s found in the autorefractor, or why we don’t just use what’s in the previous glasses prescription — because patients demonstrate different preferences. That’s why this is a subjective technique. If we did it just based on the objective findings, then there would be no need for the subjective portion. So there’s something that can happen between the objective measurements, and yet what the patient demonstrates is a preference. What’s clear, and remember, that “conditional” piece. When we talked about the initial objective of subjective refraction, we wanted the patient to be able to see comfortably, and so I think, at least in my experience, that’s where that has come in, where you may find something objectively, but that’s not what’s preferred. I can’t say exactly why that is, but that’s what happens in that subjective piece of the procedure. The next question is: When do we need to add cycloplegic drops before doing refraction? So this is done more commonly in the pediatric patient population. So the reason that you’re using cycloplegic drops is because the patient — you are suspecting that the patient is accommodating, and they’re accommodating enough to impact their distance vision, and the distance prescription. So almost exclusively, this is used in the younger patient population. Even then, I will usually still do what’s called a dry refraction, to get a sense of what the patient’s correction is, without the cycloplegic, and then compare that to the cycloplegic findings. So the next question is: Do I have any tips on binocular balancing? This goes back a little bit to my previous lecture. I didn’t cover it so much here. Personally, I don’t binocular balance most of the time on my patients. After I was in practice for a while, and I was getting enough feedback, I really sort of fine tuned my monocular subjective refraction, but the binocular balancing, I think — you go through it step by step. Some patients respond to it well. And others may not. So more often than not, if I have to modify the binocular balancing technique, I may try and simplify it, as much as possible. So instead of maybe dissociating with prism, I may just cover one eye at a time, and that’s a different type of binocular balancing technique. Or just trying to check the best corrected acuity, binocularly. As opposed to monocularly. But I don’t have quite as many tips for binocular balancing, as opposed to really fine tuning the monocular refractive findings. Do you have any list that we can consider to work with kids in order to know the correct power and the ideal age? I don’t have that offhand. I think there might be some list that exists, and if I’m interpreting this question properly, correctly, you know, at a patient’s — at a child’s age, what acuity could you expect, sort of developmentally? And this is probably more applicable to much younger children, a much younger pediatric population. So 2, 3, 4, 5 years old, as opposed to 10, 11, and 12. I don’t have that list offhand, but I do know there are resources that exist, outlining what acuity you should expect, based on the child’s age. Question three says axis? I think you mean power. I think you are probably right. I will make that edit. For myopic correction, do you prescribe exactly the same cycloplegic refraction, or a bit more minus, which the patient accepts? So I think it depends. If you’re including a cycloplegic refraction, that means you’re either suspecting that the patient is hyperopic, or a latent hyperope, or that you’re detecting pseudomyopia on the refraction, meaning that the patient is taking a myopic correction, but they are either not as myopic, or actually hyperopic, so in that case, it will depend on many more factors. What was the patient’s complaint coming in? How old is the patient? What were the dry refractive findings, compared to the wet? Are there amblyogenic risk factors? There are a lot of other factors to consider, when determining what you end up prescribing. In all likelihood, if you know that the patient should be getting a lower prescription, based on your cycloplegic findings, at a lower minus prescription, then you should take that into account, as opposed to giving more minus. You may consider giving less. But this is a little bit of a complicated question, because there are more factors that you would need to take into account. The next question is: Do you always trust the autorefractor? Or do retinoscopy for every patient you have? Some of this will depend on the age of the patient. For younger patients, for the pediatric population, I’m more likely to rely on the retinoscopy findings. I think there’s evidence to show that the pediatric population is more likely to overaccommodate when they’re in an autorefractor. So in that case, I may more commonly perform retinoscopy. Whereas in the adult population that I work with, I very commonly use an autorefractor. What is the high cylinder range which should be considered for patients who are sensitive to axis change? That is an excellent question. I’m trying to think if there is sort of a rule, or if it’s more of an estimate. I would say my personal experience, versus maybe what I was taught theoretically — probably anywhere between 1.5 and 2 diopters is where you should start being aware of how large of axis changes you’re making somewhere. I mean, a diopter may be okay. You can make 15 or 30-degree axis changes to start with, and then narrow that down to smaller changes, but around a diopter and a half to two diopters, I would start being a bit more careful, making smaller axis changes. Because the patient’s more likely to be sensitive. Again, that’s not a hard and fast rule, but they’re probably more likely to be sensitive to axis changes, once you get up around that range. Great presentation. How would you go about a case of anisometropia having +1 in the right eye, and +5/-3*140 after subjective refraction? Great question. The questions I would have back at you would be: How old is this patient? What is their best corrected acuity? Because if it’s a pediatric patient, then I would be more likely — let’s say a younger pediatric patient, who does not already have amblyopia. I would be more likely to prescribe a higher amount of plus and cyl in the left eye, because again, we’re trying to prevent amblyopia. But if this is, let’s say, a full adult patient, maybe let’s say somebody in their 30s, and they come in, and let’s say they’ve never worn glasses before, and this is the prescription that I’m finding, I’m definitely not going to be giving anything close to this in the left eye, because the patient is probably going to be very uncomfortable, if I gave the full prescription, or anything close to it in the left eye. So assuming this is an adult population, they are probably already amblyopic in the left eye, so I might just give a full correction in the right eye, and a balance lens in the left. So a lot of this, what would be chosen to be prescribed, would be based on the age of the patient, and how much of a risk there is for them developing amblyopia. The question here is: How accurate is retinoscopy for preverbal children? So I think this is more dependent on the examiner’s skill, as opposed to the age of the patient. So the more skilled the examiner is at performing retinoscopy on very young children, infants, you know, between infancy and around age 2, the accuracy of retinoscopy, I think, is going to be impacted much more by the skill of the examiner than the age of the child, at that point. So it should be fairly accurate if the examiner is experienced in working with young, young children. Which is the best in refining sphere between the duochrome test and binocular balance? So I’m not entirely sure what this is is asking. Is it asking if you would use duochrome for binocular balance or not? My personal preference, throughout years of practice, is: I know that the duochrome test exists. I know how to perform it. I do not use it very often, if ever, in the clinical setting. The duochrome test, at least clinically, anecdotally, in my experience, I’ve gotten such varied, conflicting responses that I have chosen really not to use it all that much over the years. I’ll either use a +0.50 sphere check, the prism dissociation for binocular balance, there are other techniques. So my personal preference is that I have steered away from the duochrome. It’s good to know how to do, if you do need another option, but that is not one of the tests that I commonly go to first, because my patient population over the years has had trouble really adapting to that technique. If after using the trial frame, one does not get a satisfactory response from the patient to be able to prescribe, what do you do then? So my question here would be: What is it that is causing the lack of satisfactory response? Is it that the patient’s not comfortable? Is it that the patient’s vision is reduced? Because that’s two different things. If the patient is not comfortable, then you may need to adjust what you’re showing them in the trial frame. Let’s say you’re giving them a high cylindrical correction, and as you’re showing it to them, they’re not comfortable in it. So you may need to start reducing the cylindrical correction, until you find a balance between: Is it clear and comfortable? And sometimes I’ll have the conversation with the patient that: This is comfortable, but it’s not as clear. We have to decide which one we’re going to prioritize. Because if I give you what makes it clearest, it’s not comfortable, and it doesn’t seem like you want to wear it. So we may have to compromise a little bit of clarity for comfort. If it’s not satisfactory because the patient’s vision is still reduced, I think the next thing that you need to do is figure out why the vision is reduced. Now that you’ve used your pinhole acuity, and then gone through the entire refractive sequence, if it’s still reduced, then the next question would be: Is there a pathological reason for the reduction in acuity? And that’s the next thing to investigate. And so something very common: A patient could have cataracts. And so then the explanation is: You may not be happy with your vision through the glasses, but that’s because you have cataracts. And that gives you a whole other area of something to discuss, as opposed to just focusing on the glasses prescription. So it’s really coupling those two together. What is the patient’s refractive needs? And what is the ocular health status? What if the trial lens and the phoropter gives different results? So that may be definite. More often than not, I would say, what I find in the phoropter and what I find in a trial frame — it can be often different. Because this is, again, taking what I’m finding in the phoropter from my subjective refraction results to then: What do I actually think I’m going to prescribe? And this is more talking about prescribing now, so this is sort of the next step, which obviously — this isn’t the extent of the presentation here, but it’s sort of: How do you do the step-by-step technique for refraction? What are some common things that we may run into, that we need to troubleshoot? And that was today. And the next step, then, is how do you decide, finally, what to prescribe? And that’s where, more often than not, you’ll get a different finding in the phoropter than what you show in the trial lens set. It’s tough to answer that in a vague way, but very often those will not be exactly the same, because what you’re putting in the trial lens is what you’re actually thinking of prescribing. It could be the same, but it doesn’t have to be the same as what’s in the phoropter. So the next two questions are about the duochrome. Do I do duochrome test at all? Almost never. And is duochrome required for near correction too? Why? I’m trying to think… I do not think that duochrome is indicated for near testing. I’m trying to think if I’ve ever seen it done for near. For near correction? No. And again, we didn’t cover that today. But this is all based on your distance correction. Assuming that you’ve balanced everything between your two eyes for the distance correction, then that should not need to be done again at near. So when you’re prescribing an add, you’re looking at different factors, but then trying to balance between the two eyes should not be as much of an issue or priority, assuming that you’ve already done that at distance. So let’s see. If the cylinder is, say, -4 on retinoscopy, and the autorefractor, and the patient doesn’t accept more than -2.5 diopter, what would you prescribe? I always have questions for the questions. My question would be: What do you mean by doesn’t accept more than 2.5 diopters? Does that mean they’re not comfortable in more than 2.5 diopters of cyl? Or when you’re going through the power refinement, they don’t take any more than 2.5 diopters? So you show them 2.75 or 3, and they’re consistently saying they want the less minus? So in those two cases, if they’re consistently saying that they want the less minus, but let’s say their acuity is reduced, you can do what I said before, by just taking out the JCC, and showing them the difference between, say, a -2.50 and a -3.50. And see if that improves their vision. So what you’re doing, when you’re going through subjective refraction, you want to try and find what the best corrected acuity is. That doesn’t necessarily mean that’s what you’re going to give the patient. So let’s say they do end up accepting more than -2.5 diopters. Let’s say this go up to -3.50. And you’re able to get their best corrected acuity with that. But you don’t think you’re gonna prescribe all of that, because that’s a high amount of cyl. So then maybe you trial frame and show the patient, and maybe then they don’t accept more than 2.5-diopters, because if you give them any more than that, it may be uncomfortable. And that goes back to what I was saying before, where you would say: Okay, we’re trying to balance out clarity and comfort. So I could make your vision clearer, but it’s not going to be comfortable. So right now, we may have to lower the prescription, make your vision a little bit blurry, but to the point where you can tolerate it, and then over time maybe be able to increase the power. So it depends — that question depends on what you mean by: “doesn’t accept more than 2.5.” What if your patient is not comfortable with your refraction? What will you change to make them comfortable? Especially a patient with aniseikonia. Again, it depends on what you think the source of the discomfort is. Do you think it’s the anisometropia that may be existing between the two eyes? Or do you think that it’s a high amount of cyl? Usually it’s not just a high amount of sphere. The common culprits for discomfort are going to be if there’s a high amount of cylinder, or if there’s anisometropia, whether that be the sphere or the cylinder. And so, again, you would then trial frame, and try and figure out: If I reduce the cylinder, does that make it more comfortable? If I reduce the anisometropia? So keeping the full correction for lower power eye, but then maybe reducing the power for the higher power eye. Can we come up with a combination that is clear and comfortable to a level that’s acceptable for the patient? But I think in these cases, the most important thing to think about is how you educate the patient, how you explain it to the patient. Because I have had very direct conversations with the patient, saying: This is what I’m finding. But it’s not comfortable for you. Now we have to make a decision. Now we have to make a choice. And I bring the patient in to make the choice. This is what I’m finding. It makes your vision nice and clear. But you don’t like it. It’s not comfortable. It’s making you feel dizzy. I would not recommend going with this, because you don’t feel comfortable in it. And if you don’t feel comfortable, you’re not going to wear it. So let’s try and find a weaker prescription that may be a little bit blurry, but at least it’s comfortable. And then we can increase the prescription from there. So that’s a more common conversation that I’ll find, regardless of what the situation is, and the specific changes that we’re trying to make. Are you doing any more online lectures? I don’t know. We don’t have any additional lectures lined up, as of now. But stay tuned. While doing retinoscopy, when you see the scissor reflex, does that always mean that the patient has keratoconus? No, it does not. The scissor reflex could be that you’re very close to neutral. I think more often than not, if you see the scissor reflex, it could mean that you’re close to neutral, as opposed to that your patient definitely has keratoconus. I mean, certainly keeping keratoconus as a differential for why you may be seeing that is true and important, but it could also just be that you’re close to neutral, and that’s why you’re seeing that scissoring. When doing near vision testing, do you use one eye at a time or both eyes at the same time? So typically, I conduct near vision testing, which I know we didn’t get into today, with both eyes. Binocularly. Again, this goes to: If you’ve done everything that you were supposed to do, at distance, you corrected each eye to its best corrected visual acuity, you balanced the vision between the two eyes, that all should apply at near as well. This is generally speaking. I mean, certainly there are times where you can get mismatched acuity at near. But if you have 20/20 in the distance, OD and OS, you really should be getting 20/20 at near, OD/OS, if they’re able to read 20/20, or whatever best corrected acuity they get at near, should be similar between the two eyes. So typically when I do my near vision testing, I do it binocularly, on the basis of that rationale. The next question: How much spherical difference between the two eyes is usually tolerated by a patient? Oh, that’s a great question. And I don’t have an exact answer. So there may be a theoretical answer that I’m not aware of at this moment in time. But… Sort of anecdotally, clinically speaking, it can vary from patient to patient. Some of it also will depend on if it’s a first prescription, versus an existing prescription. So someone could have 2 diopters of anisometropia, but if they’ve been wearing that for years, then they won’t have a problem tolerating it. If it’s a brand-new prescription, they might have more of an issue, and that’s where trial framing can be the most helpful thing that you can do, before actually giving the prescription. What is your guideline in prescribing in hyperopic children? So this, again, is sort of multifactorial. How old is the child, how much hyperopia are we talking about, is there anisometropia, is there astigmatism, are we worried about amblyopia, do we think there’s a risk factor for amblyopia. So all of those factors will need to be considered, when finally prescribing. So I don’t have one hard and fast rule. You have to take all of that into account, before you decide what to definitively prescribe, especially in children, especially if there is a risk for developing amblyopia. Let’s see. My question is: Are there any tips you can give, when refracting a patient with significant difference in the refractive power of both eyes? For example, a case of anisometropia, with a difference of 2.5 diopters between both eyes? So this goes back to the question we just had. I think what I would keep in mind is if this is a first prescription, or if the patient has already been wearing glasses, and if the previous prescription was similar. If it’s a first prescription or very different from the previous prescription that they have worn, I would read it very lightly. I would trial frame, maybe cut the prescription — not the prescription, but cut some of the prescription down. It depends how much prescription is in one eye versus the other, and what the patient can tolerate. So how old is the patient, do they have amblyopia — there’s all these other factors. But this is, again, where you would definitely want to trial frame, before the patient leaves, in this case, to see: Can they tolerate the difference of the anisometropia, or not? And if they can’t, then you may need to reduce the power. It depends how much of that you can reduce in both eyes, versus the one eye that has the stronger power. You may need to try a few different things while you’re trial framing. Which type of retinoscopy is good for student practice? The spot or the streak? That is also a good question. I don’t know if there’s really a difference for student practice. I’ve used both. Predominantly, I’ve used the streak. But I’ve also used the spot. The spot, I’ve found, to be much less common just in my practice, but when I did use it, I found it to be very helpful. I found it to be easier in finding the principal meridians. I don’t know if there’s a hard and fast rule for one versus the other. Some of it may boil down to just how the student responds, what they find easier to see. If it’s easier to identify the principal meridians with the spot versus the streak. But I personally have used the streak most of the time, but did find the spot very easy to use when I did use it. What is your recommendation for accommodative spasm? That is a whole other question, a whole other lecture, that I don’t think we can get into right now. But a great question. What do we do if we get different retinoscopic responses in children? So I’m not entirely sure what you mean by different retinoscopic findings in children. Do you mean… Different findings between the two eyes? Different findings throughout the procedure? If it’s the difference between the two eyes, then you need to think about what you’re going to prescribe most likely for amblyogenic risk factors. If you’re getting different responses throughout the procedure, it could be that the child’s fixation is changing, and so their accommodation is fluctuating, while you are performing the procedure. So there are a few different types of retinoscopy that you can use, to try and account for that. There’s one type of retinoscopy in particular where the child can look directly at the light, and then you perform retinoscopy. So instead of having the child fixate in the distance, they can fixate directly at your light, and that may help to control the accommodative response. It depends on what type of situation you’re talking about. The next question: What should be the minimum diopter difference between two eyes? So in right eye, if it’s +1.50, or the left eye, -6? I guess I don’t know what you mean by the minimum diopter difference between the two eyes. So I guess the question becomes: If you were going to reduce the prescription, normally you would want to reduce the prescription the same amount in each eye. But part of this also becomes a question of: How old is this patient? Are we trying to prevent amblyopia? Or is this an adult patient? And they already have amblyopia? So now we’re just thinking about what to prescribe to maximize their vision and comfort? So that’s the thing that makes the biggest difference. When do we know we are not doing peripheral refraction in a dull glow in cataracts or other opacifications? So if your patient has cataracts, or some other type of opacification, you should be able to see some of that while you’re doing retinoscopy, or even if you decide to sort of skip forward and do direct ophthalmoscopy. If there’s a very dull glow, so yes, it certainly could be because there is a cataract there. And again, that’s something that you may be able to detect, before you even start the refractive findings. But you could also have a very dull glow because of high refractive error. So if you’re getting a dull reflex during retinoscopy, it could be that the prescription is very high. It could either be high minus or high plus. And if that’s the case, you can then put in a very high — let’s say even +5 or +6 or -5 or -6, and then see if that increases the reflex. If it becomes brighter. Because it could just be that it’s dull, because of the amount of refractive error there. Someone asked: How do you prescribe prisms? That’s a very good question. Something for a whole separate lecture. Some of the questions are: Why are you prescribing the prism? What symptoms are you hoping to resolve? So there are a lot of factors that go into prescribing prisms. If a patient has other complaints, like dry eye or allergic conjunctivitis, would you rather treat, and for how long? And then give the patient another appointment for their refraction? So I think preferably, so part of it depends on how severe the condition is. And do I think that it’s impacting their vision to the point where it will prevent a reliable refraction? So if it’s mild, let’s say someone has very mild dry eye, and their cornea is intact, there’s no punctate keratitis, it’s just maybe some mild staining on the conjunctiva, then I will do the refraction, proceed, and probably even finalize the prescription. If they have allergic conjunctivitis, if they’re tearing a lot, if there’s a lot of chemosis on the conjunctiva, if there’s staining, I think I would do the refraction another day. So that boils down to how severe the condition is, and do I think that it’s impacting their refractive error. If it’s mild and I don’t think it’s impacting their refractive error, then yes, I’ll continue with the refraction. If it’s fairly significant, and I think that it needs to be treated before I can prescribe, then I would do the refraction another day. What role does antifatigue lenses have? I’m not sure what specific type of lens you’re talking about. So I know there are some lenses that utilize prism for antifatigue. There are some that utilize tint. There are some that sort of have coatings, or even a blue-blocking coating. I think it depends. It’s very situational on the specific type of lens. And the patient’s symptoms to begin with. Any tips or techniques in performing retinoscopy in a patient with media opacity like a cataract? It may be limited. Your ability to perform retinoscopy could very much be limited if the patient has a significant cataract. If the cataract is dense, then you’re really not going to be able to get very reliable retinoscopy findings. That may be one of those instances in the beginning where I had your four most common starting points. Retinoscopy, autorefraction, lensometry, or from scratch. So even if you have a retinoscope, if you’re not able to get findings, if the patient has a dense media opacity, or they have exceptionally small pupils, it can be really difficult to get good retinoscopy findings. So you may just have to start the refraction from a zeroed out phoropter, and then make those larger changes depending on their acuity and their age and what you suspect is their refractive error. How much time do you take for refraction? So this depends on a few things. The age of the patient. If the patient has been to the eye doctor before. If I speak the same language as the patient. So patients, if they’re brand-new to having an eye exam, everything will take a little bit longer. I will explain things a little bit more, so that they understand what’s happening. Certainly if I’m using an interpreter, because I don’t speak the same language as the patient, it takes a little bit longer. But probably on average assuming everything is sort of average, average adult patient, if we speak the same language, if they’ve been to the eye doctor before, then maybe 5, maybe 7 minutes, depending on how complicated the refractive error is, and how sensitive they are to blur. But it will range very much so, from patient to patient. If there’s a difference of more than 4 diopters between the two eyes, can you create diplopia? One eye is normal and the other is pseudophakic? I’m not sure if I’m interpreting this question correctly. So if the patient is pseudophakic, that’s going to create a whole other… Well, pseudophakic, as opposed to aphakic. I’m not entirely sure what you meant by that question, sorry. How much objective refractive deduction is needed if given one cycloplegic, 2 atropine, 3 cycloplegic tropicamide cycloplegic? I also don’t know what is meant by that question. If you’re performing a cycloplegic refraction, whether that’s using cyclopentolate or atropine, although I think atropine is not very commonly used for cycloplegic refraction. It’s usually used for a prolonged need for cycloplegia. Or you could use two drops of tropicamide to get a cycloplegic effect similar to cyclopentolate. How much you would deduct from the refractive error or how you would manipulate the final prescription, based on what you compare to the dry, versus the wet refractive findings will depend again — and I know I’ve said this a lot — on the patient’s age, if there are amblyogenic risk factors, what the patient’s complaint might have been, so there’s no one hard and fast rule about how much to modify a prescription from the cycloplegic versus the dry refractive findings. Can we give mobile phones with sound as fixation targets for pediatrics? I’ve certainly done that before! You know, I think ideally having something farther in the distance that’s a larger screen to reduce the stimulus for accommodation would be more of a priority. Whereas if you have a phone, even if you’re holding it a little bit farther away, it’s going to be harder for the child to see. But I can’t say I haven’t done that before, because looking at a big E on a chart is not interesting to a child. So sometimes you just have to use what you have at your disposal. But I think ideally having a larger screen that’s at the distance, so that it will encourage fixation for the child, but not stimulate accommodation, would be the ideal. Do additional coatings on spectacle lenses have an effect on the patient’s comfort levels? This sort of goes back to what another question was asking. And some of it depends. If you combine the scientific research, compared to patient experience, I mean, I know a lot of the research that’s been done in the area of tinting is very variable. When I worked in a low vision setting, and I was prescribing tints on a very regular basis, it varied so much from patient to patient, what their preference was. And it didn’t necessarily depend on their condition. So is it possible that certain coatings or tint could improve patient comfort level? Sure. It’s possible. How much of that is based on the individual patient, versus actually grounded in scientific research? I think that varies quite a bit. Does UV protection increase myopia? I do not have the answer to that. I know there’s a lot of research in myopia, myopia progression, exposure to UV light, recommendations for amount of time that should be spent outside. I don’t know the exact answer to that. There are definitely other faculty members that I work with that are much more qualified to answer that question. So I am not going to attempt that at this point. The next question. How do you modify the retinoscopy results for children when they fixate on the light instead of a distance target, or do you not modify the results? You do. I haven’t done this procedure in a while. I don’t see as many children anymore. You modify your test distance, and because of that, you modify the subsequent net retinoscopy results, but I would have to get back to you with the specific modification, because I have not done that procedure in a while. I believe it’s Mohindra retinoscopy, that’s the procedure that I’m talking about. So if you were to look that up, Mohindra — that’s the procedure where you could reduce the test distance, do the procedure in the dark, and have the child look directly at the light. But because you’re making those modifications to the test distance, you then would have to modify how you change the retinoscopy findings from the gross versus the net findings. Have you noticed inconsistencies in refraction due to prolonged screen viewing? Do you recommend additional coating on spectacles for such cases? So yeah, going back to the same thing… Certainly the eye strain, asthenopia, that’s experienced with prolonged screen time is a very real problem that many, many of our patients are dealing with. Whether or not, again, coatings specifically alleviate some of that strain… In my experience, and from what I know in the literature, it can be a bit of a mismatch. So I know a lot of the lens companies now are promoting blue blockers. Having coatings that are blue blocking. But I think the identify has been fairly mixed on that. And so certainly I know sometimes that’s offered to the patients. Are you interested? This could help. I think it depends on how you present it to the patient, as opposed to: This is guaranteed to help. Because I don’t think that we know that for sure. So is it possible? It’s possible, but again, I think there are some mixed results, when we talk about what our patients may be experiencing anecdotally, versus what has been substantiated in the literature. Do you still use the lower minus prescription to prevent increasing myopia? I do not believe — and you might have to fact check me on this a little bit — but I don’t believe that purposefully prescribing a lower minus prescription has been proven to be effective in increasing the progression of myopia. Particularly if the patient needs that prescription. So if you’re purposefully giving a lower amount of prescription to blur the patient, that’s one thing, versus: Are you trying to give the lowest myopic prescription that makes the patient’s vision clear? So those are two very different things. Giving the lowest amount, the least minus, most plus, is a very typical endpoint that we’re aiming for, when we’re talking about subjective refraction. But if you are then purposefully — if you are then purposefully reducing the prescription even further, so that now the patient’s about 20/30, when they could be 20/20, I don’t think that that has been shown to be effective in increasing myopia progression. But again, I know that there’s a lot of research currently going on in that area. And there are other people that can give much better answers than I could in that specific area. How do you identify children if they are bluffing in refraction? That is another excellent question. Something that we definitely didn’t have time for. It might be a good topic for another talk. For particularly maybe one of our pediatric specialists. There are definitely a number of techniques that you can use to determine whether or not the child — if we’re talking about children in this instance — are giving you honest feedback during the refractive process. Certainly we can rely a lot on our objective findings as much as possible. There are other techniques that we can use. But we just don’t have time to get into that. Is wearing blue blocking lenses outside unhealthy? Good question. I’m thinking of all that I’ve read and heard in lectures about blue blocking lenses. I don’t believe I’m familiar with any reason it would be unhealthy. I think the difference is that we see this marketed — the blue blocking lenses — as something that’s marketed as — it’s going to increase your comfort when using computers. It could impact your refractive error development. There could be damage being done to the eyes by using the devices that we use, and the blue light that comes off of those devices, that’s where it’s a bit more mixed. But I’m not familiar with any reason that it would be considered unhealthy. But definitely I need to do a little bit more reading in that area. When should someone do refraction in soft contact lens wearers? So typically, if you’re fitting a patient in soft contact lenses, you usually are starting — the starting point is the patient’s refractive error. Their refractive findings from being refracted either via trial frame or phoropter. And then you work off of those findings to then choose contact lenses and fit someone in trial lenses. So usually you should be refracting, or have at least the refractive findings for someone, before you start the contact lens fitting process. And yes, thank you very much. Someone included from the previous question — it’s -1.25 is added to the final ret results for Mohindra. Thank you very much for fact checking me on that. I thought it might be something in that neighborhood. But I did not want to give you incorrect information. So we made it through all of the questions. I hope this has been helpful. I hope some of these tips are just very practical. This is all put together based on my years of practice, seeing my own patients. But then also teaching this content in the classroom, and in lab, but then also in clinic. So I hope that this has been helpful, and good luck in your practice.

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June 3, 2019

Last Updated: October 31, 2022

5 thoughts on “Lecture: Refraction: A Step Up From the Basics”

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