Dr. Susan Cotter on Amblyopia and Beyond

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Published in Eye Care
Expert Opinion / Interview · December 03, 2015
Dr. Susan Cotter on Amblyopia and Beyond
Interview with Susan A Cotter OD, MS, FAAO Interview by Kathy F. Freeman OD, FAAO

Dr. Kathy Freeman of PracticeUpdate recently caught up with our guest, Dr. Susan A. Cotter, Professor of Optometry at the Southern California College of Optometry at Marshall B. Ketchum University, at the annual meeting of the American Academy of Ophthalmology (November 14–17, 2015; Las Vegas). Here they talk about the session that Dr. Cotter participated in, Amblyopia and Beyond: Current Evidence-Based Pediatric Eye Care.


Dr. Freeman: Welcome, Dr. Cotter. Tell us about your session; was it specifically concerning the PEDIG (Pediatric Eye Disease Investigator Group) studies?

Dr. Cotter: Thank you for having me. The session was the first-ever joint educational program sponsored by the American Academy of Optometry and the American Academy of Ophthalmology. This inaugural program was the result of a collaborative effort to support joint educational initiatives, and this particular symposium was the first step in this direction. We presented the same symposium at the American Academy of Optometry meeting in New Orleans (October 7–10, 2015), and now just presented it the second time here at the American Academy of Ophthalmology meeting.

The topic pertained to evidence-based pediatric eye care, and most of the evidence was based on the results from PEDIG studies. We discussed treatment of four conditions: amblyopia in younger children; amblyopia in older children; intermittent exotropia (IXT); and convergence insufficiency (CI). The discussions were based primarily on the results from PEDIG studies—both randomized clinical trials and large-scale observational studies.

Dr. Freeman: Would you give your impression of how you think the PEDIG studies have changed the way amblyopia is treated in practice?

Dr. Cotter: The results have impacted clinical practice in several ways. I think many practitioners now prescribe the child’s refractive correction first and wait to see how much (if any) treatment effect occurs from the optical correction alone over time before instituting any form of occlusion. Note that I’m not talking about the effect we get from eliminating blur from uncorrected refractive error. I’m talking about measuring best-corrected visual acuity through the refractive correction at dispensing and then having the patient wear the glasses or contact lenses to see how much treatment effect occurs over time before instituting any form of occlusion. Certainly, this has been a significant change in the way that I treat amblyopia, and it has been a change in other doctors’ practices as well. In fact, this was a question asked at the symposium, and the doctors who answered it (one a pediatric ophthalmologist and the other a pediatric optometrist) both said that prescribing the optical correction alone for a period of time was the biggest change in their clinical practices.

We see fairly good results over time from continued wear of the optimum refractive correction. On average, there is approximately a 3–LogMAR line improvement in amblyopic eye visual acuity. I think this is important because, from the child’s perspective, it’s a lot easier to patch with visual acuity that is 3 lines better than what the child had initially.

Dr. Freeman: What is the typical protocol to follow?

Dr. Cotter: Measure baseline visual acuity when you dispense the optical correction and follow the child out, say 4 to 8 weeks. If there is an improvement in visual acuity at the follow-up visit, then I typically instruct the patient to continue with the optical correction only until the next follow-up visit 4 to 8 weeks later. I continue to do this until visual acuity stops improving. If at this point, the patient still has residual amblyopia, then I institute some form of occlusion (typically, part-time patching or atropine).

Dr. Freeman: Well, it seems to me that it’s so much easier (for everyone) to initially put the glasses on a child, than to try to begin glasses as well as patching therapy at the same time.

Dr. Cotter: I agree—I think that one treatment at a time is much easier for many families. Also, think about it from a compliance perspective—if a child was 20/100 at baseline and, after a couple of months of wearing glasses, he/she is now 20/50, already the parents and child are encouraged about the visual acuity improvement in the amblyopic eye. The improvement found is not only motivating for the family, but it will now be easier for the child to patch with a 20/50 eye than with a 20/100 eye. So, it is likely to be less burdensome which might result in better overall compliance with treatment. It is a win–win all around.

In addition to prescribing refractive correction and occlusion sequentially, PEDIG study results have led to other changes in clinical practice. These other major changes include prescribing fewer hours of patching when prescribed, an increase in the use of atropine penalization of the sound eye, and treating older children.

Dr. Freeman: Dr. Cotter, from your perspective, how far-reaching is the impact of the PEDIG study results relative to amblyopia?

Dr. Cotter: There is interesting medical literature out there that says that it takes a while for healthcare providers to change their clinical treatment protocols, despite evidence that there might be more effective treatments than what they are currently prescribing. That said, I think that many eye care providers have changed the way they treat amblyopia. In particular, I think that the PEDIG study results have had a big impact within optometry. Most schools and colleges of optometry are PEDIG clinical sites, and therefore the results of the PEDIG studies are presented to the students just as fast as they’re published. If you think about it, the majority of our graduating students right now don’t know anything different about amblyopia treatment than what they are taught by their professors, most of whom happen to be PEDIG investigators. Thus, the majority of our students have never even heard of “full-time” occlusion being prescribed for amblyopia. And practicing optometrists who attend continuing education programs on amblyopia that are provided by PEDIG optometrists are also changing the way they treat amblyopia. I truly believe that the PEDIG studies have had a remarkable impact on the way the eye care community is treating amblyopia in 2015. I can’t speak as much for ophthalmology because I’m not as familiar with their training programs; however, many academic sites are involved in PEDIG and many of these programs are training pediatric ophthalmology fellows. So, there has to be some impact there as well.

Dr. Freeman: Are there any plans for the PEDIG investigators to study amblyopia intervention in young people beyond the age of 17 years?

Dr. Cotter: We’re not against studying older patients and it has come up as a possible study question, but we don’t have anything in the pipeline right now. However, it might be a bit difficult for PEDIG to conduct such a study because approximately two-thirds of our investigators are pediatric ophthalmologists, and they typically don’t see many adult patients. Thus, while there would certainly be some interest, sufficient recruitment for a study of adult amblyopia could be a potential problem.

Dr. Freeman: What about the dichoptic approach to amblyopia, with binocular video-gaming? Is there any interest in that from the PEDIG study group?

Dr. Cotter: Actually, we have an ongoing clinical trial, ATS-18, that is looking at that right now. The study population consists of children from 5 to less than 17 years of age. The children are randomized to either 2 hours of daily patching or 1 hour of binocular game play on an iPad.

The game, developed by Robert Hess and coworkers in Montreal, is a Tetris-like anti-suppression game. We already have about 350 children between the ages of 5 and 12 years who have been randomized. We were fortunate to reach our enrollment goal for the younger kids very quickly. Enrollment is still open, however, for children in the 13- to less than 17-year range. Our results for the younger cohort will likely be published sometime in 2016—so keep your ears open.

There is a lot of interest in this area of research, and we are dipping our toes in the water with ATS-18, which is the first large randomized clinical trial evaluating binocular anti-suppression therapy on the iPad.

Dr. Freeman: What would you say is the take-home message to the readership about the IXT portion of the symposium?

Dr. Cotter: The take-home is that, while we have published two papers reporting randomized clinical trial results on part-time patching for IXT, we still have a lot of unanswered questions in regard to other IXT treatments.

Our objective for the part-time patching study was to determine the effectiveness of this treatment for IXT in children. We found that, over a 6-month period, there was very little deterioration, defined as the IXT breaking down to a constant XT or a loss of near stereoacuity. While not everyone interprets the data from these papers exactly the same, we noted at the symposium that watchful waiting is a reasonable thing to do. My opinion is that we don’t have to rush young children off for surgery or even other forms of treatment because very few of these children with IXT had a decrease in their near stereoacuity or converted to a constant XT.

PEDIG is currently planning a randomized clinical trial for IXT, which is probably going to roll out in February; we are really excited about it. The goal of the trial is to evaluate the effect of overminus lenses for IXT, not only what happens short-term, but what happens long-term and whether there is a sustained effect once we take these kids out of overminus. PEDIG also has an ongoing randomized trial evaluating two surgical approaches for IXT.

Dr. Freeman: And what about CI?

Dr. Cotter: We discussed the Convergence Insufficiency Treatment Trial (CITT), how we interpreted the results, and how it impacted our treatment recommendations for symptomatic CI in children. We also discussed the results of a trial that PEDIG conducted called the CITS (Convergence Insufficiency Treatment Study), which compared home-based computer therapy versus pencil pushups. After discussing both studies, I also mentioned the on-going clinical trial, the Convergence Insufficiency Treatment Trial – Attention and Reading Trial (CITT-ART). There are eight clinical sites (optometry and ophthalmology) across the United States that are presently recruiting children 9 to 14 years of age with symptomatic CI; we’re in our second year of recruitment. The primary outcome measure is reading comprehension. Secondary outcome measures include other tests of reading comprehension, as well as attention. It was nice to be able to introduce the study to the audience and say, “Keep your eyes peeled, we’re going to have some interesting data in the next couple years to answer the question of whether treatment for symptomatic CI has an effect on reading performance in school-age children.”

Dr. Freeman: Well, all of this work that you’re doing seems to be making the appropriate treatment of these conditions so much easier for the primary care practitioner because you are really breaking it down into steps that can be easily instituted as therapy in an office without having to do a lot of traditional vision therapy.

Dr. Cotter: You know, that is another change I’ve noticed. I do a fair number of CE presentations, and one of the topics I’ve always lectured on is amblyopia. I feel that there are more primary care optometrists out there who are now comfortable with and willing to handle amblyopia in their practices versus 10 to 15 years ago. I think that this is because there is a strong evidence base for treatment, and it seems easier now that we know optical treatment and lesser amounts of patching are effective.

Dr. Freeman: Is there anything additional you would like to share with the readership about the important work you are doing with amblyopia and children’s vision?

Dr. Cotter: Yes, and thanks for asking. We would like for members of the eye care community to partner with us in our on-going studies by helping us recruit eligible children. So, I ask that all practitioners with offices in close proximity to our clinical sites refer patients from their practices who appear to be eligible for the studies.

There are certainly many docs who are not able to provide active vision therapy in their offices for kids with symptomatic CI, so referring them to the CITT-ART study is a win–win for everyone. Parents are usually very grateful to be referred to a NEI-funded clinical trial for which there is no cost to them. It actually makes the referring doc look good. And, of course, the patients will be sent back to the referring doctor’s office after the treatment. Likewise, there are docs who might not be comfortable with treating teenagers with amblyopia, and yet that teenager and his/her family might be very interested in enrolling in a study that is evaluating cutting-edge binocular amblyopia treatment on an iPad which is not presently commercially available. So, refer that patient to a PEDIG ATS-18 site!

Dr. Freeman: Where would an eye care provider go to find the sites or find how to refer somebody?

Dr. Cotter: For CITT-ART, the website is http://citt-art.com. For PEDIG, people can go to http://www.pedig.net to find out where the nearest PEDIG investigator is located and the studies that are currently recruiting. The clinicaltrials.gov website also has information about the trials.

Dr. Freeman: Anything else that you would like to add?

Dr. Cotter: Yes—I should mention that the views that I have expressed to you are mine only, and do not represent those of the PEDIG, the American Academy of Optometry, MBKU, or any other professional organization to which I belong.

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