Lecture: Binocular Vision Part III: Managing Binocular Vision Disorders

This live webinar is the third in a three-part series and covers the management of common near binocular vision disorders, and in particular outlines common vision therapy activities for managing convergence insufficiency.

Lecturer: Hilary Gaiser, OD, MSc, New England College of Optometry, Boston, USA


(To translate please select your language to the right of this page)

DR GAISER: Hello, everyone, and welcome to binocular vision part 3 of my series of three lectures, and today I’ll be speaking on managing binocular vision disorders. I’m Dr. Hilary Gaiser, assistant professor at the New England College of Optometry, and I’m looking forward to speaking to you today. So welcome, everyone, and thank you to Orbis for letting me present today. So today’s lecture objectives: Managing binocular vision disorders, vision therapy — it’s a huge topic, and I’m just going to do a quick introduction to the topic. And more of a basis from primary care optometry. So today’s lecture objectives are to learn how to manage common near binocular vision disorders, focusing on near. These are the ones that most commonly impact, for example, a student’s ability to do well at school, or could impact a person at work. You’re also going to learn how to perform common vision therapy techniques. Again, there’s hundreds of different vision therapy techniques out there. Focusing on ones that are more easy to implement from more of a primary care perspective, that don’t involve a lot of cost and are fairly easy and portable to take with you wherever you need to go. And I’m also gonna cover how to manage convergence insufficiency with vision therapy. Convergence insufficiency is one of the most common binocular vision disorders. And we as primary care optometrists need to be able to manage this. So I just want to get a gauge from the audience. I’m gonna ask you two questions here. Regarding your comfort level in the management of binocular vision disorders, and first of all, I want to know: What is your comfort level with binocular vision disorders that are not vision therapy? Okay. And so I see there’s a variety in the audience. Some not comfortable at all, some very comfortable. The majority occasionally manage some, but not all binocular vision. So I hope this lecture helps you today. And now I want to know: What is your comfort level in implementing vision therapy? Good! This is great. So I see again a wide range in the audience, but the majority have learned about vision therapy, but have never implemented it. So I hope this lecture will be very good and very informative for you, again, doing things more from a primary care perspective, using things that are easy to implement with your patients. Again, this is just such a wide topic, I’m unable to cover everything in only 50 minutes today, but I just wanted to give you some binocular vision management resources that are very handy. The first two favorites of mine are: Clinical management of binocular vision from Scheiman and Wick. Very great book, very comprehensive. It walks you through all the procedures, management, diagnosis. And a great resource for convergence insufficiency treatment is the manual of procedures for the convergence insufficiency treatment trials. I recommend you read their work. A very good evidence-based method of treating convergence insufficiency. Some other sources here. I just want to include a couple sites for some vision therapy equipment. You don’t have to use these, but I just wanted to include them if they will be useful for you. So the common near binocular vision disorders that I’m going to focus on today — limited time, so I’m going to focus on four today. Ones that impact your patients at near. These are going to include convergence insufficiency, ocular motor dysfunction, convergence excess, and convergence insufficiency. So I’m gonna get started with the management of accommodative insufficiency. Accommodative insufficiency, we find the symptoms include blur, headaches, difficulties with reading, shifting focus, words might be moving on the page, and when we do workup, we find reduced findings with minus lenses and reduced amplitude of accommodation. If you want to learn more about this, please see my previous lectures, where I covered more of the diagnosis and the testing to come up with a diagnosis of the different binocular vision disorders. So just touching briefly on that. So how do we manage accommodative insufficiency? We’re gonna start with correcting any refractive error, even if it seems small. This is a great start. Sometimes even that small prescription for glasses can help. And then addition lenses are a good starting point. These lenses typically range from 0.75 to +2. And we really need to make sure we’re doing a good job putting them in a trial frame, gauging our patient comfort, having them perhaps read a little bit in the waiting room, and seeing how well they do. With that said, this is our typical starting point, but additional vision therapy can make the treatment with lenses even more effective. And just don’t think that you’re gonna focus on your accommodative treatments, accommodative vision therapy. We also need vergences as well. With all of these, we need to work on the accommodation and the vergence system. It’s all being trained. We don’t want to focus solely on one or the other. We’re gonna go into ocular motor dysfunction next. Signs include difficulties with pursuits, saccades, fixation. Often parents come in and say my child has been reported for a tracking problem. They’re having a hard time reading. Without using a finger. Having a hard time looking to the board and copying back down to the paper, for example. They lose their place frequently. Often there’s a lot of head movements when reading. And when you’re doing the exam you’re finding things often with fixation during the cover test. They might do poorly on the DEM test, and they often might use a finger to help direct fixation. Ocular motor dysfunction is associated with other binocular and accommodative anomalies, frequently. So we just need to be able to ferret that out, to do our testing, and see if there’s any associated binocular vision or accommodative anomalies with the oculomotor system. How do we manage ocular motor dysfunction? Addition lenses are typically not helpful at all, unless there’s an associated accommodative problem. Then they might be helpful. So steer away from addition lenses. Vision therapy is the treatment of choice. We need to include both accommodative and vergence techniques, monocular and binocular techniques. It’s really important in ocular motor dysfunction — typically, because it’s so associated with reading and tracking — and school work — that there’s communication to everyone involved in the child’s education. There’s letters sent to the teachers. Parents understand the condition as well. So that everyone is on the same page. Something that might be helpful before you start the vision therapy is some compensating strategies. These can be using a finger or a ruler to underline sentences, help with that tracking, when the child is learning how to read. I’m just gonna cover, again, lots of different methods of doing vision therapy for ocular motor dysfunction. I’m just going to focus on a few today. These include letter circling, or filling in letters, visual tracing, Marsden Ball. And sometimes we do need to worry about suppression. I’m gonna teach you how to do a vision therapy technique to help with suppression called the red/green glasses and flashlight. So letter circling is going to help improve smooth pursuits, saccades, and tracking. The procedure is… We have an example here. You can use different printouts with different letters. Use a magazine. You know, something with appropriate-sized print for the patient involved. And you’re gonna have them either circle or fill in the letter. Like fill in the Os, fill in the Ps. Es and Os do work best, because of their frequency. And other vowels. You’re gonna have them put an eye patch on. They’re gonna start monocular. They’re gonna follow along and circle or fill in all the letters that you indicate, and then you’re gonna have them do, say, a paragraph of similar length. You can use a magazine or you can use the preprinted sheets that I have. You’re gonna record the time it takes and record as well the number of mistakes. So you’re gonna be training your patient how to do this. And when mistakes are minimized and they’re sort of reaching a timing plateau, then you can remove the eye patch, and they can proceed from doing this task monocularly to binocularly, to increase the difficulty level. Another technique is visual tracing or visual scanning. Saccadic workbooks. Mazes. There’s a lot of different things you can do in this category to help with your ocular motor function. Again, the goal of visual tracing is to improve smooth pursuits and tracking. Lots of different workbooks. I just have a sample today of some visual scanning books. Saccadic workbooks. Lots of different things you can use. Different mazes. Even those Where’s Waldo books. Anything that gets the patient looking and tracking, that you can get some measure on. And we always start monocularly, and then progress binocularly. Because it’s harder binocularly. You can have the patient — if they’re really struggling at the beginning, starting with a pencil to help with that tracking, and then progress to using their eyes only. And again, working through the books binocularly, without mistakes, is the endpoint. Starting out monocularly, and then moving to binocularly, without mistakes. Another technique that you can use for ocular motor dysfunction is something called a Marsden Ball. I have just an example here. It just hangs from the ceiling. This one doesn’t have any letters or numbers, but you can put them on. You can put different colors and what-not. And this technique helps the patient develop appropriate ocular motor coordination. There’s lots of different things you can do with this. So lots of different techniques, if you read some of the literature. Lots of different variations. I’m just gonna tell you a few today. One is called the circle technique. You suspend the ball, the patient stands in the middle, they’re gonna swing the ball around their head. Make sure there’s enough clearance so it doesn’t hit the patient. And the patient is gonna sort of track the ball, and then when it goes behind their head, you’re gonna train them to saccade over and they’re gonna keep tracking the ball. Look over, follow the ball, look over, and you can reverse directions. This helps them with their tracking. They can also do something called batting or bunting. They’re gonna hold a little bat, and this is particularly good if you have different numbers and letters on the Marsden ball. They’re going to call out a number, letters, say A, and they’re gonna try to hit the A on the ball. Again, to help with tracking and finding those different targets, and then moving their body and hitting that target. You can do colors on the ball. Different letters, different numbers. There’s a wide variety. It’s a really good technique, just because there’s so many different things you can think of to do with it. The endpoint would be that you’re gonna start using it — they’re gonna start tracking and following the ball, it’s going to increase to where they’re hitting numbers, you start monocularly and then progress binocularly, and the endpoint is really that they can bunt the ball, contact the appropriate letters, numbers, and colors when called in a minimal time with both eyes open. So next I’m gonna go into just one of many, many techniques to work on patient suppression. The purpose of the red/green glasses and pen light technique is to decrease the intensity and frequency of suppressions. You’re gonna start with conditions that are gonna causes the patient to be in a state where they’re least likely to suppress, and then they’re gonna move on to normal conditions. In this technique, the patient is going to wear their red-green glasses, they’re gonna hold a 6 prism diopter base down prism before the dominant eye, they’re gonna view a pen light in the distance, you’re gonna ask them how many colors and lights are seen, and you want them to maintain diplopia. You want them not to be suppressing. So you’re gonna probe them for questions. How many colors are you seeing? How many lights are you seeing? You want to make sure that they’re seeing two. And then you’re gonna slowly increase the room illumination, because that will make it harder to not suppress. And then when they’re able to do that with the full room illumination on, then you remove the red/green glasses and you have them do it just with the prism. And if they’re having trouble, if they’re suppressing, you’re gonna decrease that room lighting a little, until diplopia is recovered, and slowly increase the room lighting while they’re maintaining diplopia and not suppressing. This endpoint typically requires about two to four weeks of in-office and home therapy. And again, the goal is when that patient can maintain the diplopia without the red/green glasses and in normal room illumination. There are a lot of different techniques that follow in this category. Another one being… Playing cards, going through playing cards. These are great for take-home therapy. They put on their glasses, and they’re only able to see what the cards say if they’re not suppressing. You need both eyes with the red/green glasses. You can play some games. It’s a good way of training the visual system to not suppress. That’s just an option. Again, lots of different techniques in this category. So you can choose one that’s easy for your patients to use. I’m just using a couple of examples. So next I’m going to transition into convergence excess management. Symptoms or signs of convergence excess are very similar to accommodative insufficiency. Such as holding reading material very close. They might close an eye or they might have head tilt after visual fatigue. Signs include esophoria near greater than distance, high AC/A, low divergence, normal NPC, elevated convergence, and difficulty with minus lenses. So in convergence excess, we’re going to start with glasses, correct any refractive error, even if it’s minimal. Sometimes this can help. Plus lenses may or may not be helpful. You always need to be careful prescribing plus with convergence excess. If the patient has esophoria, that’s where you want to start out, eliminating that first, if it’s present. And always trial frame them and follow them closely to see if it’s working. The treatment of choice, management of choice, is vision therapy for convergence excess. And you would work with the patient on improving their relaxation of accommodation, and also working on divergence techniques. So I’ve covered so far accommodative insufficiency, ocular motor dysfunction, and convergence excess. Some of the more common findings. I’m now gonna transition into convergence insufficiency, where I’ll be spending the majority of the talk on a vision therapy program. Because again, this is one of the most common binocular vision disorders, and the one I think you’ll be most likely to treat in more of a primary care setting. So symptoms include double vision, eye strain, headaches, difficulty with near tasks, you’re gonna have that classic receded near point of convergence, exophoria near greater than distance, low positive fusional vergences, low AC/A ratio, and difficulty to clear plus lenses on binocular accommodative facility. Again, all of these I covered in previous lectures on diagnoses and methods of evaluating binocular vision disorders in my part one and part two lectures. So if you are interested, you can always follow up and watch those. Often associated with convergence insufficiency is an associated accommodative dysfunction, so we need to make sure we’re ruling that out as well. So how do we manage insufficiency? Convergence insufficiency? I mentioned the CITT studies, the convergence insufficiency treatment trial studies. Out of these studies, home/office-based vision therapy is really the treatment of choice. Out of this research, they recommended a program of 12 weeks with good compliance. You might go even to 24 weeks with moderate to poor compliance. Recommend one hour office visits every one to two weeks, where you’re working with the patient in-office, with vision therapy, to monitor programs. You would implement changes. For example, if the patient is doing really well, they reached the endpoints for monocular training, you would then make the change that they would then go binocular. And they also looked at the home treatments, and found that about 15 to 20 minutes of homework or vision training at home five days a week also is very useful for managing convergence insufficiency. So you really need that component of in-office and at-home, to really reach peak management. So just a word about glasses and convergence insufficiency. Glasses are not the treatment of choice. They make it frequently worse. Unless there is an associated accommodative insufficiency, and we’re gonna go quickly back to my previous lectures a little bit. Make sure we’re ruling out pseudo-CI first. But in some rare instances, glasses may work. Again, we would have to trial frame, repeated binocular vision testing, really make sure this is appropriate for the patient. But vision therapy is the treatment of choice. Again, sometimes — and this is not for everyone — base-in prism with or without plus may work in certain cases. If you’re thinking about including this, you must always complete a prism adaptation test first, and when you’re prescribing, you’re gonna start with the least amount of prism that satisfies Sheard’s criterion, and split the prism between the two eyes, and always make sure you’re doing a trial frame for comfort. And it’s typically not successful if the patient is greater than 10 to 12 prism diopters. It’s just not typically going to work. So again, going back: Vision therapy is really the treatment of choice. Based on the literature. I recommended at the beginning the manual of procedures from the CITT studies. It’s really good and available on the web. To really outline a good vision therapy program for CI. Lots of different techniques in there. I’m only gonna cover a few, and really, I’m doing a more simplified version of this today, to share with you all. But it’s a good resource there. In this vision therapy management for CI, there’s multiple stages. And multiple techniques. And each technique has a specifically stated endpoint. And going back to that home therapy, there should be about three tasks, for a total of 15 to 20 minutes, five days a week, with your follow-up. We don’t want to make it too long. We want to make sure the patients can complete the home therapy. It is work. It’s really hard work for our child to do, for example, so keeping to that 15 to 20 minutes, instead of 30 minutes to an hour, really helps with compliance, which really helps with treatment. So when we’re talking CI and vision therapy, we need a program to develop — not just vergence. We also need to focus on the accommodative system as well, as well as ocular motility and suppression. So today, I only have time to cover a sampling of different vision therapy procedures, focusing more from a primary care perspective. So for vergences, I’m going to discuss how to do Brock string, loose prisms, Lifesaver cards, and eccentric circles, and for accommodation, we’re gonna talk about monocular examine binocular chart rock, monocular and binocular lens rock. For ocular motility, I already discussed ocular motor dysfunction. We’re going to use the same training exercises in our vision therapy for CI. And I also covered the suppression and the techniques to train for suppression, with the red/green glasses and flashlight. And you can incorporate that into your CI vision work. Outlining the sequence of training, I’m going to go into more of a three-phase structure a little later. Just thinking about which techniques are a little easier to start with and which are harder. For vergence, typically we’re gonna start with the Brock string and proceed to the Lifesaver cards, eccentric circles, and loose prisms, for the ocular motor, we’ll start with the circling and filling in the Es and proceed to the Marsden ball. Same with accommodation. We start monocularly before we train binocularly. So I’m just going to get started with working with the different vergence techniques you can do. I’m going to cover Brock string, as I mentioned earlier, followed by Lifesaver cards, and eccentric circles. So Brock string has been around for quite a while. It’s quite common, so it works well. I have an example right here to share with you today. So the purpose of the Brock string is to help develop the patient’s ability to voluntarily converge, diverge, and to develop a normal NPC. Very simple. It’s a meter of string with two beads. Red bead and green bead. Some also have a yellow bead in the middle. So you’re gonna have the red bead at the end of the string at one meter, and you’re gonna start the green bead at 40 centimeters. You’re gonna have the patient — sometimes you need to tie the string to a doorknob, or have an assistant to help hold the end of the string. But you’re gonna hold the bead at 40 centimeters, you’re gonna have the patient look at the green bead, and describe and really probe them and encourage them to describe it. At this point of the technique, the patient should report one green bead and two red beads. Or otherwise they should be noting and describing physiological diplopia. So you should point to the green beads, say: What do you see? How many beads are you seeing? And what are the strings doing? Can you describe what the strings are doing? So just figure out appropriate language to use with different aged patients when you’re doing the technique. After you’ve established with them that the green bead is single and the strings are crossing when they’re looking at the green bead, you’re gonna have them switch fixation to the red bead, and then you’re gonna probe them and ask them what they’re seeing. At this point, the green beads should be double, and the red single. Again, noting physiological diplopia. And you’re gonna instruct the patient to always try to make the strings cross at the bead. Once the patient is able to fuse that near and far bead, you’re gonna have them maintain fixation on the near bead for five seconds, and then switch to the far bead and maintain for five seconds. So that’s the cycle. One, two, three, four, five, one, two, three, four, five, that’s a cycle. If the patient’s having trouble fusing near and far beads, you can have them touch the bead, and this allows the kinesthetic feedback. And also you can use minus lenses to help stimulate convergence if they’re really having difficulty. I’m gonna go into all these cues for feedback when you’re doing vision therapy, and ways to make tasks or techniques more difficult or easier for a patient at the end, so stay tuned for that. I’m just giving you the basic procedures. And really designing this so you can print out these slides and use them as procedure techniques. Know they’re a little bit wordy. So I’ll print them out for later use. After you do the cycle, you can have the patient perform ten cycles. Green bead, red bead, green bead, red bead. After ten cycles, you’ll have them move 40 centimeters. Again, we’re starting at 40 centimeters, and the goal is to be able to move the bead to 5 centimeters away from the nose. And be able to converge and diverge. Converge and diverge for distance — for 10 cycles, comfortably. So the goal is to start at 40, and be able to fuse both the near and the far bead for 10 cycles. Something else you can also use is you can do bug on a string, which means you’re just pulling one of those beads along, and you’re having the patient focus on it. That technique also works well. It might be a little bit easier for them. Next I’m gonna cover Lifesaver cards. These are relatively easy to obtain. They come in a transparent and a white card version. Transparent, just because it’s transparent, helps patients learn divergence a little bit easier. Some patients have a hard time diverging with the white card. The purpose of the Lifesaver cards is to increase the amplitude of the negative fusional vergence and positive fusional vergence. Increase the latency of the fusional vergence response, and increase the velocity of the fusional vergence response. The procedure is: The target separations are already printed on the cards. The patient is going to start at the bottom, they’re gonna try to fuse for 10 seconds, and then jump to the next target to fuse. So it already has the gradations on the cards. This is a good place to start after the patient has been successful with box string therapy. The endpoint is where the patient can achieve chiastopic and orthopic fusion and switch between the two types of fusion, and move the cards laterally. That’s a really good endpoint for this procedure. The next technique I’m going to cover is called eccentric circles. I have some of these today. They also come in a white and a transparent version. The transparent ones help with divergence. The white helps with convergence. You can also use the transparent for convergence as well. The purpose is just like Lifesaver cards, but these are the next level of difficulty. It’s to increase, again, that amplitude of negative and fusional vergence, and decrease the latency of the fusional vergence response and increase the velocity. The patient is gonna hold on… They have As and Bs. They’re gonna start with the As. Hold them in front and they’re going to encourage them to converge. Try to move them with your eyes. Try to keep the center target clear. So for example, some of the cards have antisuppression. Some are red/green for antisuppression or accommodative. Those are held together, and converging, they will perceive them as floating closer, and then when they’re diverging, they will perceive the circle floating away. People commonly think the As are for convergence and the Bs for divergence. That’s not necessarily the case. You can do both. They just have to understand which one should be coming closer and which one further away. So in this technique, unlike the Lifesaver cards, where it has the separation on the cards, you do need to — you’re gonna have the patient hold them and fuse, and then slowly, slowly bring them apart, and that separation — you need to calculate the prismatic demand. So if the separation is 12 centimeters, that’s a 30 prism diopter count. So the whole goal is that the patient should be able to converge with a card separation of 12 centimeters, and diverges with a card separation of 6 centimeters. And be able to switch between the two types of fusion, with cards held at 6 centimeters. And to maintain that fusion with a card separation of 6 centimeters while moving them laterally or in a circle, and still being able to appropriately converge. So next up are loose prisms. These are typically the next level in difficulty for vergence training. A wide variety. An example here. Prism. You can use lens and trial lens sets as well. This is simply gonna help increase the patient’s ability to converge and diverge. You’re gonna have a 20/40 size target at 3 meters. Some intermediate distance, and at 40 centimeters, and you’re gonna typically start with the 40 prism diopters, before the right eye, and look at the distance target, and try to make the double image into one. When the image is single, you’re gonna remove the prism and repeat the procedure. And keep doing that 10 times. Move away. Single. Single. Single. And you’re gonna repeat that. They’ll work on fusing and you’ll repeat that procedure ten times. They’ll repeat that from distance to an intermediate and near target, and when the patient is successful, first you’re gonna repeat and switch the orientation of the prism size. You were doing base out before. Then you’ll do base in and repeat for ten times, and when the patient is successful, you’re gonna repeat the sequence, but increase the prism. If the patient is doing 4 base out, I’ll do 8 with the base out. And if they’re having a little bit of trouble going to that next 4 prism diopter step, you can go halfway, and go in 2 prism diopter steps. And your endpoint for this technique is when the patient can successfully fuse 20 base out at all distances. 12 base in, at intermediate and near, and 8 base in at distance. So you see there are slightly different endpoints. So when you’re increasing the prism by multiples of 4, obviously for base out it’s going to be easier, and then you’re probably going to do 2 prism diopters for base in. And these make great take-home therapy techniques. I’m gonna go into some accommodative techniques next. These are gonna include monocular letter chart rock, monocular lens rock, binocular letter chart rock, and binocular lens rock. So the goal is to restore normal monocular accommodative amplitude and facility. You’re gonna start with the left eye occluded. You’re gonna typically have a chart with 20/40 distance letters. Some people in the literature recommend 20/30. There’s a little variation here, but typically 20/40 distance letters, 10 lines with 5 letters each per line, and you’re gonna hold that 40 centimeters from the patient. They’re gonna hold one. You’re also gonna have one farther away on the wall, and the patient is gonna start a little bit closer and then back away, so you’re gonna put the chart up, and the patient is gonna see that they’re clear. You’re gonna have them back away, until the letters become blurry, and then they’re gonna walk a little bit forward, or until they reach a distance of 3 meters and the letters are still clear. The patient is gonna hold that small chart of 20/40 near letters and they’re gonna call out the letters on the top line while moving closer. When they can’t keep the letters clear, they’re gonna move the chart a little bit further away. So you’re seeing that they’re really going from the far chart until it’s blurry and a little bit closer, and doing the same thing at near. And then do it a little bit further away. So this is the distance you want to use. Then they can shift focus. They’re gonna read the first line of the distance chart. They’re gonna look at the first line of the distance chart and read one letter off the distance chart and one letter off the near chart, until all the lines are complete. Sometimes if they’re having a hard time doing this, we’ll start with lines — they might be reading one line at distance, one line at near, and then you’re gonna go to one letter, one letter. And just thinking of ways to make this a little bit easier at first, so we don’t frustrate our patients, and then increasing the difficulty level. So after they’ve done the chart, they’ve read a letter at far, read a letter at near, they’re gonna repeat this procedure, but with the right eye occluded and with the left eye doing it. The endpoint of this technique is when the patients can successfully clear the near chart at a distance that’s equal to the age-appropriate amplitude, and clear the distance chart at 3 meters. So when I was telling you how they were walking up to the chart, then walking a little closer, if that distance isn’t quite 3 meters, they’re gonna be working on this each time they’re in for therapy, until they can come back and hold that near chart at an appropriate distance and be 3 meters away from the distance chart, and still maintaining focus while switching between the two charts. Next technique is on monocular lens rock. And this is gonna help normalize the accommodative amplitude and facility. We’re gonna include again — we’re always starting monocularly and proceeding binocularly for these techniques. Left eye will be occluded, you’re gonna hold age appropriate reading material at 40 centimeters, and use lenses or flippers to switch between, and ask the patient to clear the print, while alternating between the two lenses. And then you’re gonna have them switch eyes, occlude, since they’re starting with the right, gonna have them occlude the right and go to the left, and you’re gonna move through a series of lens designs, to increase the difficulty. I’m gonna go over the different types of lenses that you can use. For binocular letter chart rock, just like monocular chart rock that I described, we’re going to go through the same procedures of having the distance chart and the near chart, but instead of having one eye covered, the patient is now gonna do this technique with both eyes open. So again, I know it’s a little wordy. The goal is to be able to have you print this out and use this as a procedure reference guide, when you’re doing these techniques. And the endpoint for binocular letter chart rock is the patient can successfully clear the near chart at an appropriate distance for their age, and clear the distance chart, while maintaining focus, switching between the two charts. And then binocular lens rock… Just like monocular lens rock, except instead of having one eye occluded while they’re doing it, they’re going to do it with both eyes open, and the goal is to have them be able to complete 20 cycles in one minute. So a cycle is plus, minus. That’s one cycle. The goal is to have them be able to do 20 cycles in about a minute. These are some of the typical lens rock designs. You’re gonna start out with plus and minus 0.5, and gradually progress to plus and minus 0.25. Plus is gonna max out at around +2.50. You can increase the minus up to -6, and then you’re gonna go in 0.5 diopter steps. So say you’re at plus or minus 2.50. Then you’re gonna go +2.50, -3.50, and so on and so forth. You can order these in basically any power that you want. If you don’t have flippers, you can also just use loose lenses and switch between the two. Very portable, easy technique to do. So I was gonna discuss vision therapy feedback mechanisms. Communication is so key with your patients, when you’re performing these techniques. And particularly children might not always understand what you’re asking them or wanting them to do. So I’m just gonna go through some of the different feedback mechanisms, just so you can have an understanding of what’s going on, and how you can apply the vision therapy. So some of the key mechanisms, just to be aware of or to think about, is the concept of diplopia or double vision. This is usually typically the easiest cue to explain to patients. And this is important to stress, when using the Brock string and the physiological diplopia during Brock string. Again, just something like: Is this double vision? Do you see two? Just so patients are aware of this. It’s very important, if they’re either under or overfocusing, for example, with eccentric circles, to stress that they keep that clear, so they have an understanding of what blur is, so when they’re going on in their normal day-to-day life, they have an understanding, and when they’re progressing through vision therapy, they have an understanding of what blur is. Suppression is also something we need to stress. This can vary between the training implements. Usually if you’re doing therapy to treat suppression, depending on the method that you’re using, you can ask: What are you seeing? If you’re using the playing cards, they can be suppressing the red. It can vary between the different implements, so you just need to be aware of what you’re using so you can remind the patients of the cues to pay attention to. Luster is a combination of colors when the patient is asked to fuse them. And a lack of luster could indicate that the patient is suppressing. Kinesthetic awareness is the understanding of converging and diverging. Just think about how to understand that and express that to your patients. Do you feel like you’re pulling your eyes in or relaxing your eyes a little bit? Another concept that’s more related to perceptual changes is the concept of SILO or small in and large out. These are perceptual changes that occur while fusing and divergence and convergence demand is varied. The target — it doesn’t always work for everyone, but the target might, when you’re progressing through therapy and asking how other things work, the target might be smaller and move closer to the patient when converging and be larger and further away when diverging. You can ask: What does the target look like? Do you notice anything? They’re reporting that it’s becoming smaller and moving closer. You can help them correlate that with convergence. Oh, you’re bringing your eyes together. You’re converging. When they’re reporting this response. Float is associated with SILO. That’s when you’re converging the targets, appearing to float closer, and the targets appear further away. Localization is a concept when you’re able to point to where the target appears to be when fused in space. This is the concept of physiological diplopia. And the pointers should be in the area where the visual axes cross. They will see one target. For example, in the Brock string, pointing to the bead where they’re converging. I know these concepts can be a little deep. Poll question three: True or false — a lack of luster can indicate that the patient may be suppressing. True or false? Good. Everyone was paying attention. Almost everybody got it. The answer is true. So I’m just gonna wrap up the lecture today, in regards to vision training, vision therapy, with convergence insufficiency. Pencil push-ups are very common. A very common thing to prescribe for primary care optometrists, and in particular — promoted as an efficient and effective home-based CI therapy, but studies have reported mixed results, and the CITT studies reported not great results for pencil push-up therapy. So it’s really not a great — even though it’s really easy — it’s not a great thing to recommend for take-home vision therapy. So I want people to be aware of this. Really encourage you to read some of those really great CITT studies. And that these studies have really shown — and other studies, not just the CITT studies — have shown that outpatient and office-based vision therapy is more effective than home-based vision therapies only, such as pencil push-ups. So I want you to be aware of this and what’s out there in the literature. So other considerations from the studies: Just really stressing good communication with your patient. And the goals of vision therapy, continually stressing what the patient’s problem is. You’re often working with children. It’s a lot of work to do vision therapy. You need to really stress: Oh, your problem is tracking. You’re having problems focusing at near. And really why are we doing this? Why is the vision therapy helping you? So they understand that they have this issue, and to reach their goals, they’re really gonna have to work at it. Make sure you’re stressing the changes occurring in the patient’s visual system internally, versus just the equipment. The patients may think that they’re getting better because of the equipment, versus how they’re training their eyes. So just stressing that subtle difference there. Just be aware of frustration levels with your patients. Fidgeting, avoiding the work, might indicate that the techniques are a little bit too hard at the time. We might need to make them a little bit easier. It’s always good to start at an easier level, a more baseline level, and gradually increase the difficulty level, so we’re avoiding frustration. So how do we increase or decrease difficulty for our techniques? Just adding this extra component, if your patient is having trouble with any of these techniques. For divergence, we can increase the working distance, use some plus lenses or potentially base-out prisms, and for convergence, basically the opposite, to decrease the difficulty level. Minus lenses, base-in prism. You can also increase the working distance. If we want to increase the difficulty level, say our patient is doing really well with our eccentric circles, we want to increase the difficulty a little bit, and we’re currently training divergence, we can use some minus lenses or some base-in prism or decrease that working distance to increase the difficulty level. And conversely, if we’re gonna increase the difficulty of your convergence, you can use some plus lenses, base-out prism, or decrease the working distance. So these are simple things to do, if you kind of work through the program, and you still want to work with your patient a little bit, you can increase the difficulty level just simply using these methods, or if they’re having a little bit of trouble getting started with a particular technique, we can decrease the difficulty level. This just makes everything a little bit more flexible, just considering these. So last I’m just gonna ask you the last poll question. For example, how would you increase the difficulty level of the Brock String Procedure when treating a patient for CI? Add plus lenses, decrease the working distance, add base-out prism, or all of the above? Good. And you can do all of the above. And so I’m just giving you this, really going through more of a three-phase nitty-gritty vision therapy for CI. I’m gonna go through this really quickly with the idea that you can print this out or write this down for your own use. This is based on the CITT study’s procedures, and I modified a little bit, to include just more simple or more simple and portable vision therapy training techniques. I didn’t get into stereoscopes, things like that, knowing that not everyone has access to these, so really keeping things simple from a primary care perspective. So I’m just gonna go through quickly the three phases. Phase one is gonna train that gross convergence. These are some of the different techniques you can use. Brock string, Lifesaver cards, loose lens, accommodative rock. All monocular. So again, we’re gonna start with gross convergence, use some of the more simple techniques for positive fusional vergence, and starting with monocular accommodative techniques, and then what you can use — which techniques you can give the patient for take-home therapy, and the different endpoints. So when the patient is reaching these different endpoints, then we can slowly move on to the next phase, which is phase 2, which is just making things a little bit more difficult. So we’re gonna ramp the fusional vergence and monocular accommodative facility. We’re gonna introduce some more difficult techniques, such as eccentric circles, flipper accommodative rock, letter chart accommodative rock. Still monocular, because our next step in phase 3 is to move everything binocularly. Again, the different techniques you can use for home VT to increase the difficulty level, and the different goal points and the different endpoints for phase 2, that when the patient reaches, then we can proceed on to phase 3. So phase 3 is when we’re jumping from monocular status and ramping up the fusional vergence, we’re making things more difficult, and doing things binocularly instead of monocularly. Again, moving on to more difficult techniques. Eccentric circles are gonna add in the loose prisms, and we’re gonna move to binocular accommodative facility. Different things you can give to your patient to take home for home VT, and just the endpoints. So the goal of this three-phase system is, by the end, the patient will be able to reach all the goal points listed on this slide. So again, this is for you to use in your practice. Feel free to use as much as you like. I just wanted you to have a good example of a three-phase system. Most certainly read through the literature, if you want to omit certain techniques or add some of your own. If you have access to other equipment, you can add that to your vision therapy program. So I just wanted to open up — we’re at the end of the hour. Open it up for any questions you might have. Again, this is such a broad topic. I highly encourage you to read some of the resources I’ve given you here. And feel free to use my slides to develop your own vision therapy program. I just wanted to cover some of the more common binocular vision disorders. I didn’t touch on amblyopia today. That’s a whole other topic I want to cover at some point, but just giving you more from a primary care perspective. So I’m just gonna open this up to any questions. Good question. What’s the minimum equipment required for a binocular vision therapy clinic to start with? Again, I would focus on things that are for convergence insufficiency. That’s one of the most common things. So you want to be able to have a vision therapy kit specifically for convergence insufficiency, that would be a great starting point. You need some sort of loose lenses to do accommodative rock, so that would be good, or accommodative chart rock. Also some sort of prisms to do vergences. The cards, Brock string — all of these that I showed you today. It’s just a good place to start. And if you want to focus mainly on treating convergence insufficiency, that would be a great place to start, I think. Okay, good. That’s great. Next question is: Which vision therapy do you advise for patients with computer vision syndrome? Good question. So computer vision syndrome is very, very broad. So I would go back to my first two lectures, and actually see if it’s just overuse on the computer, or if there’s a true binocular vision disorder. So first you would have to do a full binocular vision workup, and see if there was an accommodative or vergence issue. What that is, and then you would focus on treating that specific condition. Next question: Could vision therapy help in late age amblyopia and nystagmus? Potentially, yes. Again, this is a really large topic that I’m just not able to cover today, but there are some very good papers out on that topic. I would like to cover that at some time. So I’m just not gonna go into that right now. Good question. The next question is: What is the difference between binocular accommodative facility and amplitude? I covered this in part two, I believe. Part one or part two. Binocular accommodative facility is looking at how many cycles you can do with lenses. That’s facility. Amplitude is when you’re covering an eye, and you’re measuring how close the patient can bring the reading material. Okay. The question is: What is the best way to deal with monocular diplopia? Interesting question. When you’re talking about the visual system, monocular diplopia is not related to binocular vision disorders. Monocular diplopia has to be something that’s prior to the chiasm or the crossing of the fibers, the nerve fibers. And that typically means doing a really good workup, and looking to see if there’s any macular disorders, any ocular surface disorders, because typically monocular diplopia is an issue with the eye. It’s not related to VT. Good question. What type of vision therapy… Oops. What type of vision therapy would I prefer for patients with reduced accommodative facility? Again, I would focus on… Well, first you’ll rule out if it’s accommodative insufficiency, and you might just prescribe plus in those cases. If it’s a condition that’s related to accommodation that’s not necessarily accommodative insufficiency, I would work on the monocular and binocular accommodative techniques that I discussed. But you always don’t want to just train accommodation without also working on vergence. So you would include some type of vergence training into your accommodation training as well. You don’t want to just train the accommodative system without also training the vergence system as well. I think… That might be it for the questions. Are there any other questions out there? I had one more question. Why would it benefit the patient to learn how to see double? This is more just feedback. It’s not to see double. It’s a feedback technique, just so you can understand that they’re performing vision therapy. For example, a good example is the Brock string. Just so they understand what double vision versus single vision is. And so you want them to have single vision. You want them to fuse. But you want them to also understand what double vision is, if that makes sense. So appreciating what physiological diplopia is. What true double vision is. Particularly this is more maybe when working with a child, and so they understand what double vision is, so they can report it to you when you’re doing your training.

Download Slides


August 13, 2018

Last Updated: October 31, 2022

Leave a Comment