Interview with Emily Y. Chew, MD
Dr. Emily Y. Chew, MD is the Deputy Director of the Division of Epidemiology and Clinical Applications at the National Eye Institute, National Institutes of Health. She is involved in the MacTel Project as the Director of the Clinical Projects for the Lowy Medical Research Institute. In this role, she coordinates and plans studies including the natural history study to understand the course of disease, and to study the factors that might be associated with the disease. She also helps to plan the clinical trials that test various therapies that might be used for MacTel type 2 eye disease.
You have been involved with the MacTel Project since the beginning. In your view, what have been some of the major breakthroughs or turning points in MacTel research over the past ten-plus years?
I started working on this project in 2005. I have been impressed with the amount of information we have gathered over the years. The first were the clinical findings that resulted from immense improvement and marked development of the imaging modalities used to study patients’ eyes. This has enabled us to show retinal changes in persons affected with the disease. The pooling of data with large number of participants from centers from all over the world has been a great collaboration, resulting in excellent information. The collaborations between the basic scientists and the clinicians have also helped to bring progress to this area of research.
How is visual function assessed in MacTel patients?
What we have learned from our large natural history study is that the progression of this eye condition is exceedingly slow. Vision loss, fortunately, occurs at a glacial speed. On the average, it is a loss of one letter from the visual acuity chart in one year. One can go on for decades without changes in the vision. However, persons affected with the condition might have symptoms for years including seeing wriggly lines and having difficulties with reading without any apparent changes on the visual acuity charts. Beyond visual acuity charts, we are measuring vision by assessing reading speed and the ability of the affected retina to perceive light in very specific areas. This is called the microperimetry. We will hopefully see how well the visual function might correlate with some of the changes we see when we image the retina.
Individuals with MacTel sometimes have trouble getting an accurate diagnosis of their disease. What are some of the common misdiagnoses? Why is it underdiagnosed or misdiagnosed?
It is quite common for persons affected with MacTel to have delayed diagnoses or go through a number of tests before he or she is diagnosed with MacTel. The early signs of the disease are extremely subtle. Very specialized imaging may be helpful but not every eye doctor or optometrist might have the equipment to do such imaging. It is also not a common condition and we tend to look for what we know. There may be a knowledge gap in the community for this rare condition. However, once the clinician knows the diagnostic criteria, it is easily recognized in the later stages of the disease. It is often confused as age-related macular degeneration because new blood vessels can grow, similar to the wet form of age-related macular degeneration. There is some abnormal splitting of the retina, mimicking a macular hole. Unfortunately, such “macular holes” are rarely responsive to surgical correction. It has an association with diabetes, i.e. persons with MacTel tend to have higher rate of diabetes. Diabetic eye disease can also mask this condition.
How has awareness of MacTel within the medical community changed over the past ten years?
Although we have no formal survey of the state of knowledge of MacTel over the past decades, the number of manuscripts on this condition has increased in the medical literature. Our investigators are seeing more referrals from the general ophthalmic community, suggesting that the wider dissemination of our project may play a role in increasing awareness of MacTel in the medical community.
What are some of the important next steps in MacTel research?
We are very much involved in the clinical trials that test potential treatments for MacTel, which currently has no proven treatment. We are delighted to be leading this effort. The treatment we are currently testing is the use of an implant of live cells that produce factors that may help protect or slow down further damage caused by MacTel. We are in the phase 2 of the study and other treatments are also being considered at this point. I believe the future is bright for the MacTel Project because of the wonderful collaboration between the bench scientists and the doctors treating the patients. I also expect marked improvements in our instruments that we use for making the diagnosis and monitoring the progression of disease. We hope more drugs will become apparent as potential therapies. I like to thank the Lowy Medical Research Institute for having the vision and the generosity to support this important project.