Lecture: A Clinical Framework for Binocular Vision Disorders: Assessment, Prisms, and Vision Therapy

>> Dr. Jothi: Hello, everyone. Good morning, good afternoon, and good evening to everyone around the world. It’s been a pleasure to present in such a webinar. Firstly, I would like to thank the Cybersight and the team. It’s a privilege and honor to present in such a, you know, like a privileged platform. But first before I bring in the slides, today I will be discussing the binocular vision disorders and patients and also, before stepping into a wide variety of slides, I want to put a question for you all. Where a patient often presents with symptoms such as eyestrain, headaches, blurred vision or difficulty sustaining near work. As an eyestrain, blurred vision, and difficulty in sustaining near work, commonly mistaken — but many have a ocular disorder. In this presentation I’ll be covering the systemic approach to diagnose this condition and self-selecting the appropriate management, and my name is Dr. Sudesan Jothi. An optometrist, and at the MGR Institute in India. We’ll begin with the first slide. Before diagnosing any patient, we must first ask for a vision anomalies in four groups. Binocular vision, accommodative disorders, vertical, and ocular motor dysfunction. Binocular is further classified as low AC/A, normal and high, and this classification forms the foundation for our diagnose, which you are seeing in the slide. And then now that we know the classification, the next step was to identify the specific binocular anatomy. In this three by three binocular grid, this diagnostic grid combines the patient, distance, and interpreting these two findings together we can accurately differentiate, you know, like conditions such as convergence insufficiency, convergence excess, and by looking at the binocular alone, we know the issue. That’s what I’ve shown in the slide. Now look at a low AC/A profile. We will be seeing one by one the binocular profiles. First begin with the low AC/A, convergence and divergence insufficiency. In convergence insufficiency, greater near, with a receded NPC, and reduced vergence. And convergence insufficiency presents with a greater distance, and findings are relatively normal. There’s more to the condition. But normal issue. Here the exophoria is the same. It includes basic, and fusional dysfunction. And patient may have a minimal, but have reduced symptoms. We can find that. Now talk about high — we will discuss about the high AC/A ratio group. Here even a small amount, you can see in the slide, here even a small amount of accommodation produces this convergence. Convergence excess, near, and divergence, greater at distance. And understanding the issue helps us distinguish this condition easily. And so far we have discussed each binocular anomaly individually. This stable summarizes all of them side by side. It compares the cover test, and you can find — cover test, vergence amplitudes and vergence facility. It compares the cover test, like findings like issues, convergence, vergence amplitude, and stereo owe on sis. And this is a quick reference for differential diagnosis. By evaluating the binocular vision, we assess the accommodative system. It’s divided into four groups typically. The one is accommodative insufficiency, and ill-sustained, instability, agility failure, and excess. These present with problems with focusing forward, endurance and flexibility, as is mentioned in the slides. Next will be this slides — completed the diagnostic matrix. This diagnostic matrix help us differentiate accommodative disorders, and there’s a negative accommodation and a posterior accommodation and the — by interpreting these findings together, we can accurately identify the underlying dysfunction. This slide shows that not all patients have horizontal binocular problems. We must also evaluate the vertical deviation. We will also evaluate the vertical deviation and the ocular motor dysfunction. Vertical phorias often have limited fusion results. And the ocular motor dysfunction, leads to poor reading performance and tracking difficulties. And we’ll be moving on to a small case analysis flow. Once all the these clinical findings are collected, we usually analyze them systemically using this flowchart. The first step is to — is identifying whether the patients are exophoria or esophoria. We can follow the diagnostic for the final diagnose. In simplifies the final diagnose. For the vergence. And while for esophoria, it’s negative fusion, and option. And comparing these it lets us correct the diagnose, making the decision making process much more systemic and obvious with clear findings. Finally, to ensure the accurate diagnosis, every binocular vision assessment needs some pillars. So, we have four pillars in binocular vision. Beginning with the ocular alignment. Every binocular alignment like phoria measurement, and following this allows us to find the exact anomaly and provide the most appropriate management of patients. You can see the cover test, which is for — and the phoria measurement, and moving on to the vergence mechanism, you can see the smooth vergence, step vergence, and –. And accommodation metrics, the amplitude, and accommodative facility and MEM retinoscopy. And now we — now that we have understood that the diagnostic approach is pretty clear, the next step is let’s begin with the pillar which is the ocular alignment. The first and foremost test. It’s obtained by the optometrist is the cover test. We first perform the cover test to measure the total phoria, but breaking down the binocular fusion. We then utilize the deviation using the prism. One important clinical difference to observe the upper eyelashes carefully when looking for small vertical phorias. And we also use the exotropia control to objectively measure the patient’s control and treatment process. That’s all about the cover test. And next once we identified the deviation, the next step is to measure its magnitude. So, our — like how it has been measured to magnitude. Commonly there are two ways of subjective methods. The von Graefe test and the modified Thorington test. And the first is quick for practice. And the next one is the modified Thorington. Keeping in mind, however, that the Thorington test is performed in free space. Often the preferred method, especially in children and patients with unstable accommodation because it has excellent repeatability. Before measuring the phorias. We calculate the AC/A ratio which is for the classical binocular. And we have the gradient method is the most commonly used technique. First we measure the baseline, then we introduce a minus 1 lens binocularly and measure the phoria again. Throughout the test, the patient must keep the target clear. Because poor accommodation will result in an inaccurate measurement. Okay. Then this slide shows the vergence mechanism. After evaluating the alignment, we move to the pillar 2, once we finish the pillar 17, which is the vergence mechanics. Smooth vergence is tested using the prism in the phoropter. And then look at the BBR, the did issue blur, break, and recovery. And we look at the recoverability. And one key clinical points is you always, you know, test base before the baseload to avoid including the specimen which can affect the overall results. And next assess the vergence in the free-space. The step vergence, using a prism bar. And we observe the patient’s normal value. The patient actually at the moment recording blur, break, and recovery values. You can see the vergence prism bar glued on a stick. And then a target of 20/30, and you can convert to 40 centimeter. The technique is bracket prism power you have been seeing. At the endpoints, it’s a blur, break, and a recovery. And when the target is moved slowly, something like — we also evaluate the vergence facility using the flippers. These measures how quickly the patient can go between the convergence and the divergence. A reduced cycles per minute, which is termed to be simply as CPM, is more variability and helps to identify the specific vergence deficits. Another essential test is the NPC, which is the near point of convergence. Which is especially important in the diagnostic convergence insufficiency. The target is moved slowly towards the patient nose until the patient reports a double vision, and outwards. When — then the break and recorded points. I mean, you need to measure the — both the break as well as the recovery. Repeating the test several times helps identify the fatigue-related convergence problems that might not appear on the first attempt. It’s better to repeat it. And now we’ll be stepping into the third pillar, which evaluates the accommodation. The accommodation amplitude can be measured using the pull-away method. Or the minus lens method. The pull-away method is preferred in India. Like the overall children population because it minimizes the overestimation. And the minus lens is performed inside the phoropter, with the lens until the sustained blur occurs, and you can see that this is the patient’s maximum focusing ability. And now how to — how accommodation interacts with divergence. Measures the patient’s ability to relax the accommodation using a plus lens. While the PRA measures the abilities to measure often an accommodation using minus lenses. We also perform the accommodative facilitated testing with plus or minus prefers to access the focusing flexibility, which is in the right side of the slide. In order — in order others, for example, a low-powered are recommended because the ability naturally decreases with age. And you can see the picture slide of the flippers. And for, like, the subject you test are always supported by the objective assessment. Using a MEM retinoscopy. The patient reads while you briefly observe their retinoscopic reflex. And you can see the popping out of the major photodynamic, and more than 40 centimeter. Which like — with motion, as I mentioned, it was been accommodative lens which is nominal with certain change. And against the motion, it includes usually a normal certain range. And whereas the lens accommodates the accommodative lead, and it’s commonly seen in the access. And the key is to provide the test to avoid changing the patient’s accommodative response. Finally, we have arrived to the pillar four. We come to pillar four, which evaluates the sensory function. We first access the stereopsis with the test such as the Randot and the four-dot test. Making sure the patient does not move their head, we do the test to assess for the binocular fusion and suppression. Keeping this, asking the patients how many dots nay sees makes interpretation simple. You know that the four dots are normal fusion, two or three, and then five is diplopia. And this test confirms the brain successfully integrating the inputs. These four pillars, the actual ocular alignment, vergence mechanism or accommodation sensory can complete binocular assessment. Accurately at this diagnosis, not an anomaly, and the plan that most operate treatment for our patients. Moving on to the next slide. After completing all the sensory evaluation, and it’s time to assess the oculomotor function using are the NSUCO test. And this evaluates the saccades and the pursuits. We track how the patient goes without giving, and the section about with the head movement. The performance is based on body and head movement and ability and accuracy. The significant head or the body movements are poor tracking, indicates that it is a true oculomotor dysfunction. And this is CISS, it’s very useful. It’s very useful in the therapy. And then we have discussed about all the classifications and tests, all nose things. Now that we have complete diagnosis in our hand. So, we move on to a management treatment. The treatment is not random. It depends on the patient’s issue, as I mentioned before. Which is a primary tool. The patients with — respond well to optical treatment such as plus and minus lenses. In contrast, if you see a patient with low AC/A ratio, they benefit more from vision therapy and in selected cases, a prism. This helps us choose the most appropriate treatment for each patient. Treatment — this is the pyramid. The treatment is like an architecture of a therapy. Treatment should always follow sequence. We begin with an accurate diagnosis. And the far most and very important thing is the patient education. Because it improves the compliance. And next we improve the visual efficiency by training the accommodation and vergence and the ocular motor skills. Once these are stable, and now we focus on symptom relief. And finally, we integrate these skills, you know, into very visual performance for long-term success. This is overall a symptom mapping of an accommodation. For example, when you — when a patient’s symptoms often provide certain diagnostic close. Patients who are with accommodative insufficiency tends to hold reading material farther away. For example, in accommodative insufficiency, you can see a premature eye fatigue, generalized headache, and the classic in the –. And the patient with the accommodative insufficiently holds the reading material far away. They avoid near text. And you can see in the accommodative excess, the variables, especially after the prolonged near to distance focus slow, and have photophobia. Oculomotor dysfunction, loss of place while reading. Movement is fine. And this is the mapping of — the symptom mopping. This focuses on the symptoms associated. You can clearly see, however, the symptoms have been mapped with the specific condition. There’s some high AC/A score, greater than or equal to 21. This slide focused on the symptoms with the convergence and divergence. The patients can convergence say the words move while reading. And may cover one night. Even in convergence excess, commonly the frontal headaches with near work. In divergence excess, it produces diplopia, especially when the patient is driving. And usually present with a bright light or — and you can find that, and daydreaming is found in the divergence excess. And next the AC/A lever concept. For example, this slide complains it depends on the AC/A issue. In low AC/A issue, changes in the lens power produces a very little change in eye alignment, making lenses less effective. However, in the high AC/A, and when you come back with the high AC/A, even a small lens changes produces a significant element change. Therefore the lenses are highly effective in managing the high AC/A ratio conditions. Let’s now discuss the most common binocular anomaly which is the convergence insufficiency. It’s characterized by the greater exophoria at the end. And you know that it’s found. And it reduced PFV, post — vergence. It patient experiences eyestrain, headaches, and poor reading compensation. And often avoid prolonged near work because of the visual discomfort. And now specifically the treatment — the management of the convergence sufficiency. Management follows a step — [Audio cut out] — refractive error. It’s a universal law. So, any disorders, any anatomy can be. The first and foremost — I mean, the thing to correct from an ophthalmologist is to correct the patient’s refractive error. The goal was treatment is always an office-based vision therapy. Which has the highest success rate. For patients who cannot undergo therapy, and are living, a prism may be prescribed. And pencil push-up alone is not considered an effective primary treatment. The vision therapy progression. Vision therapy itself follows a structured progression. The phase 17, you can find this voluntary convergence. The goal is to teach the voluntary convergence and normalize smooth positive fusional vergence. You can see the Brock string and the variable tranaglyphs. And you can see it’s jump and phasic vergence. Increases the speed, accuracy, and to normalize the negative — like negative fusional vergence. The tools use ready the aper cure rule and excentric circles. Finally, we do integration and eye movements so a patient can perform visual tasks comfortably and efficiently. Now we’ll be stepping into the — our next disorder. The divergence insufficiency. That phoria is greater at distance. You can find a reduced fusional vergence. This patient is usually comfortable at near. But they experience the intermediate distance diplopia. Especially while driving or when fatigued. The symptoms are mainly related to the distance you can see in the right side of the picture. Like — like it’s a specific terms. This one is the most important slide, you know, like because not every patient with distance esophoria has divergence insufficiency. This shows the differential diagnosis. As optometrists, we must differentiate from the neurological condition such as the divergence prelaties and 6 nerve palsy. Do both things. It’s chronic and intermittent. The neurological condition presents with sudden onset. It can be a commitment deviations or associated with neurological signs. That says any patients with acute distance diplopia should be referred immediately for a neurological evaluation as well. After ruling out — before slides correlating with that, the neurological process, we can confidently manage the DI, the divergence insufficiency. And this is a ratio condition. Playing the primary role in the treatment. We first correct for the refractive error. A universal thing. Then describe a horizontal prism to eliminate the diplopia. Vision therapy might be all they do if symptoms persist. While surgery is only for severe cases that do not respond to the conservative management. We now move from the low AC/A condition to high AC/A pathway. And like — you know, like the patient is AC/A, these individuals respond very well to lens changes. If the problem is convergence excess, we are — if the problem is convergence — like something if the problem is convergence excess, we use plus lenses to reduce excess and near convergence. If it’s divergence excess, target the lens, and accommodate the accommodation convergence and improve the alignment. And moving on to the next slide, the convergence excess characterized by the normal distance alignment. But the excessive convergence during a near-work, this parent commonly presents with near esophoria, and reduced negative fusional vergence. And the primary treatment is the lens which reduces near phoria. And the prisms are only in selected cases. These are pictures of a Brock string. You can see the picture off patients with Brock string training vision therapy. And you can see the aperture rule for the convergence therapy. Finally, we have a divergence excess. Here that exophoria is much greater than at near. And patients know notice an intermittent outward deviation. Especially in vision therapy. Like when you’re tired or in bright sunlight, the first line treatment is office-based vision therapy to improve the distance convergence control over a minus lens. Maybe used temporally. Particularly in children. And while surgery is considered only for large and persistent deviations. The unified strategy. This slide summarizes the entire management approach. The first step is always to determine the AC/A ratio. And high AC/A condition. Respond to the best of the lenses. And the low AC/A ratio condition. Request the prism. Regardless, like of the conditions. We must always correct the refractive error and keep on insisting that is — it’s a universal basic thing. And surgery should be considered only as the final treatment option. And before accommodating insufficiency, we now move to the accommodative rehabilitation. Vision therapy for accommodative insufficiency follows four progressive phases. You can see the slide. For example, the first phase, the monitoring the monocular Brock, amplitude and equal lenses. You can use Hart chart and letter. And the binocular rock, and prisms and filters. And in phase III, you can find the suppression control, and the phase IV is flexibility. I wanted to mention the clinical — that the goal is to obtain the clarity between the two eyes individually. The goal for accommodative range, you can see in the slide. With plus and minus lens. Are always dependent by the age. And finally, we trained the accommodative flexibility with the rapid, near, and distance focusing. Helping a patient achieve comfortable and efficient vision in their daily life. And these are the pictures of the eye chart for accommodative. You can see the aper cure rule, the figure 7.6, and the loose lens rock in vision 7.4. And now so far we have discussed their accommodative insufficiency. Let’s look at the accommodative excess. That goal is completely different. Instead of accommodation. Also know that along with the office-based therapy, the home-based therapies when it’s adapted and followed, it shows it uses a better result. The articles have been highlighting that. When office-based vision therapy and home-based vision therapy is combined, it gives better results for the patient. And getting back to the accommodative excess. The Brock is an excellent training tool because it provides immediate visual feedback. To achieve the proper, you know — this is supported with an office-based relaxation exercises. And simply home activities to improve the accommodative controls. These are some slides — I mean, some articles — reliable articles. If you’re wanting, you will see the study is very high. In most cases, it’s asymptomatic. And I hope you can see the slides. And whatever condition always starts with an accommodation therapy. And stabilize your accommodation first and start with convergence. If therapy should always begin with the accommodation. Okay. That’s the clinician. Our treatment decision should always be evidence-based. This strongly supports, and also want to mention something about the articles. This article showses the prevalence of a non-strabismic binocular vision anatomies and a need for vision therapy, which has a high prevalence rate. The office-based therapy for conditions such as convergence insufficiency, accommodative dysfunctions and divergence excess, it’s equally very important to recognize its limitations. Vision therapy does not treat the dyslexic or learning disabilities on an exam. Treating with visual problems may improve comfort, but it does not address these underlying neurological conditions. Right. So, we have covered the overall classification, management, and the treatment approach. Let’s now apply everything we have learned to a clinical case. We have a 20–year-old college student with an eyestrain and a blurred vision during a prolonged reading. Although visual acuity and the refractive error and vergence strain are normal. The accommodation findings are normal. The case shows that the patient has a reduced accommodative amplitude, and failure on accommodative facility. And an increased MEM length. Keeping all this with the problem in an accommodative issue rather than divergence. So, using our diagnostic approach, we must first consider the convergence excess because of the near esophoria of the patient. However, there’s normal. The significant reduced accommodative amplitude, and failure with the lens, and increased — all points towards one diagnosis which is the accommodative insufficiency. This demonstrates how a systemic analyzes to reach and diagnosis accurately and it’s very patient-benefited. And now stepping into the management of the case, once a diagnose is confirmed, the treatment should address both systems and the underlying cause. We begin with patient education and prescribe a low-near addition to provide immediate relief. At the same time, remember that we started the vision therapy program to improve the accommodatingly and amplitude and flexibility. And we worked with the rule and review with the patient after four to six weeks to monitor improvement. And how the training will be used. You can also monitor divergence monitoring, the visual advice, and a very important one is the follow-up schedule. Right. We have reviewed the concepts and discussed with all those slides. Let’s review our con swept a few questions. In this question, the patient has exophoric with near convergence. You can find the popping out of the polling questions. I would be happy if you answered. All right. Okay. So, if you see the first question, right. Yes, that’s correct. It is convergence insufficiency. So, this is the classification presentation of convergence insufficiency, making it a correct diagnose. Because the exophoria is greater with near convergence, right? Most of them have been answered correctly. And next question: A classic sign of CA is a greater exophoric the previous question. A patient struggles to rapidly change focus from a board to notebook, which condition is most likely? And you can find the options, the accommodative facility, accommodative excess, and hyperphoria, and divergence excess. And wait for the answer. That’s fine. That’s perfect. Most of them has been answered correctly. Some of it, yes. The answer is accommodative in facility. This is a person — that problem is focusing on the flexibility rather than focusing distant. And the next question is which finding differentiates divergence excess from the basics of exophoria. And reduced amplitudes, exophoria, normal stereopsis and the near. Wait for the answers. Great. That’s perfect. Exophoria, greater distance. It’s significantly greater at distance and near. And basic exophoria, what are the key — one of the key signs. And the next question. Which lens is commonly prescribed for convergence excess? The high AC/A condition. You’ll wait for the answer. I think that’s perfect. 66% have been answering it correctly. Yes, it is a plus lens for near. It leads to reduced convergence demand. Because the patients have the accommodative demand. And we can do patching also. And I just want to mention that you can give patching for such a patient, right? Great. Many answered that correctly. And our final question describes the patients with the condition — which condition is most likely when both BO and BI — base vergence facilities are reduced despite normal AC/A separation? I would also like to mention that the condition in the P wave is low also they have a normal — that’s perfect. It’s fusional vergence dysfunction. Great. So with this, I had completed the diagnosis investigation and management of the binocular vision and accommodative anomalies. The systemic approach using a separate issue, appropriate clinical tests, covered the evidence-based treatment. I hope you have enjoyed it using an accurate diagnosis and the outcome. Thank you for your attention. And that I’m happy to take any questions. What is CISS score? CISS score, it’s a symptom score. Like you can use that in vision therapy. It’s a clinical tip, always .
start training patient from the convergence and divergence so it will be very easy. Like when you use the CISS questionnaire, it rules out the — it’s a symptom questionnaire. Keeping that, you can find the underlying causes. And when you do vision therapy, if this is keeping that score, you can — you can check the reliability of the vision therapy. And so I want to mention about CISS. It is used to measure something like system quantitatively. And something — something quantitative and qualitative in the therapy. What are the questions? Greater than, for example, greater than 21 is considered as abnormal. What else question? And the first — of vision therapy should be vergence and then for accommodation. Like it’s up to the base, but how I understand that, anything with disorders, it should begin with an accommodation. Because once the focusing is — who you train the focus first, the accommodation system, you can easily align the vergence system. So, we always — I’ll be beginning with an accommodation first. But it depends upon the vision that we see. The reliable source would be better to begin with an accommodation therapy first. What binocular values do you… yes, the — at test as both creating for a zero to five, like from — for — and —
In this case, I mean, which question is — like it’s better to go on with a CISS questionnaire. And also, I just want to mention that we can stabilize a separate issue using the — I mean, the CISS code. The big normative values. It would be more easy to analyze. And like the success I had with therapy at the clinic, what fines we can — in my opinion, like you know the patients lacks in the home-based therapist. Like for the vision therapy, it’s an office-based — it is produced much more reliable results. It’s for patching for convergence sufficiency. When you watch like the bi-nasal thing. You can find a better results in the therapy. Always do start. When you talk about an accommodation, it’s not about like teaming. How do I start with that? You can start binocularly if it is an accommodation. Which is the basis to learn — repeat the test. You can learn more efficiently. So the best source to learn something like — it’s to practice it. Binocular vision, and — it helps us to guide the better understanding about binocular, like, the assessments. There are multiple questions popping out. What kind of therapy you prescribe for children? Like — while the ages start with — what’s the next question? Or visual power integration? As I mentioned that this assessment, we cannot manage the underlying cause. We are just treating only the — the visual problems. I’ll also like to mention that the one thing, I mean, the back — to get better with the base. At the prospective training. Like a balance the training, all those types. Always start with the full description. And currently, having high — when checking with reflection — possibilities with time. And I also wanted to mention that the training, we should train the visual motor skills along with vision therapy. It’s a use of improvement. So, we are like — I — the vision. Who I have done my Ph.D. in sports vision. This prospective training, it leads — it does wonders. So, it’s not up to the — I mean, the high end, the super normal vision. Even with the vision therapy, we can start with the minimal amount of prospective training and balance training. It does wonders in the patients. It’s training the vision and balance. Eye, body, and mind, you know? And model and accommodative facility. Who is the visual respond to accommodation? Not directly, but indirectly, it supports the accommodation. I mean, it responds to the accommodation. But the big thing here is that a separate issue completely. But it doesn’t hide the role in the vergence system. It does have some role on accommodation. It responds minimalistically. And when it’s focusing better. It’s like a cart riding with two horses. So, if I want to go fast, I need for us to perform better. For the management, what you do. With patients and binocular dysfunction what about guides your decision better than surgery and prism? In patients with broad strabismus and binocular dysfunction, what guides you between surgery? It’s about the — I mean, when we’re done with the complete evaluation, the quantity is — matters and it’s — let’s see. It’s a broad spectrum. It depends upon the specific disorders. And the evaluation and the data we get from the patients and the diagnosis, and the clinical approach and the treatment modality. Only then we can — I mean, talk about the difference between the surgery or the prism therapy. So always first begin with a better vision therapy. And I mean, the quantities where, you know, like it’s very important while doing the vision therapy. Thank you, thank you. Joining from Kenya. What questions? How — therapy patients. How far should you flip the lens? That’s it. Do you have any questions? Diagnostic. Clinical case. I want to mention some point like my accommodation vergence team up to make it happen in the vision therapy sector. So, it’s like, as I said before, it’s like a — this point of vision therapy. The final goal is to get single and a clear vision. Especially they have — referred to the — that’s a good question. Patient thinks that vision therapy — the patient. It’s not a simple 5 minutes or 10 minutes prescription way of treatment. Vision therapy is a long-term process.S it like when you want to train your body, you need a complete activity and a long-time gym. And the same thing when I want to train my brain. You know that 60% of our brain activities are completed with, you know, that ocular activity. So, in that case, if I want to build my muscle, I need some time. Certainly, vision therapy also needs some time. This is the only way we can convince the patient. So, it’s overall — I mean, a long-term treatment. And also, we should explain that — the results are — but in the long-term way of treatment, it does wonders. Like if you heard about the patients with better vision long-term therapy. So the patient results have the vision therapy, we need to first educate them. The one thing is that they’re not aware. They have been usually seeing the instant treatments. But vision therapy does wonders only when we give it time. Because it trains the brain. It goes on with the axions. For divergence excess, will be your… the basic prism can be used for a prism therapy for a divergence excess. Challenging vision therapy. Difficulties in challenging vision therapy is that it’s not instant process. So, we should continue for the long-term process. That’s a very main difficulty. And it’s not very easy to understand. Like patients from different types of, like, in the — different types of fields are also — you can find the other — and it is just prescribing. But when you talk about vision therapy, we just want to convince them it’s a long-term process. The only difficulty is that it’s a long-term process but when the patient waits and accommodates it, it does wonders for the patients. That’s it. Any other questions? Right. Thank you all. I would like to thank the Cybersight, Andy and all the team.