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
Transcript
>> 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
Can I have the full note and video please?
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I want the lecture on video copy clip, please can I have it? I enjoy your teaching
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Thank you!
Please one webinar for cycloplegic refraction also