July 2015

 

RETINA

 

Evaluating AMD eye to eye


by Maxine Lipner EyeWorld Senior Contributing Writer

 
   
AMD

Macular Degeneration

Considering what has happened to the patients fellow eye can offer insight as to whether an eye with early AMD, such as the one on the left, is likely to become one with late AMD, such as the one on the right.

Source: National Eye Institute

Considering implications for disease progression

For a patient with age-related macular degeneration, its a pressing question with important implicationsjust what are the chances of the disease progressing in the fellow eye? AMD is the leading cause of legal blindness today, according to Ronald Klein, MD, professor, Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin, Madison.

New study results can help elucidate what the correlation between eyes may be. In a study published in the February 2015 issue of JAMA Ophthalmology, investigators found that when the disease progressed in 1 eye, the other eye tended to progress as well. What we were looking at was bilateralityif 1 eye is more advanced, whats the chance of the other eye developing a similar severity level of AMD, Dr. Klein said, adding that this is a concern for patients who are already contending with the disease in 1 eye and who understandably want to know whats going to happen to the other. In addition, this can be important for AMD trials. For clinical trials you need to estimate what the likelihood of developing the endpoint are to have enough people in the trial, Dr. Klein explained.

Studying the spectrum

Most of the information regarding risk of progression to date has come from studies examining more severe endpoints, he said. Such studies have, for example, centered on patients with end-stage disease occurring in 1 eye and the chances of doing an intervention to prevent this from happening in the other, Dr. Klein noted. However, there have been no studies done for early stages of disease, he said, adding that prior to this study it remained unclear what the risk of progression was in the fellow eye in such cases.

This population-based study was all-inclusive. It was conducted in Beaver Dam, Wis., and at the baseline examination all participants were 43 to 86 years old. Investigators then considered where on the AMD spectrum the participants fell. We took all of the people based on grading of their fundus photos and categorized the AMD severity using the scale that we developed, Dr. Klein said, adding that there were 5 levels of increasing severity from no AMD to end stage advanced disease. Following baseline exams, participants were measured every 5 years for up to 20 years. We were able to look at how the AMD progressed in each eye of an individual over time, Dr. Klein said.

Symmetrical findings

Investigators found that the severity of the condition in 1 eye tended to be mirrored in the other. In cases where there was severe AMD in 1 eye, the fellow eye tended to have accelerated progression. Meanwhile, if the AMD was mild, the fellow eye tended to have less progression. The key finding was that the condition was very symmetrical, Dr. Klein said. Over a period of time, 50% of eyes in individuals were within 1 level and 90% were within 2 or less levels. For example, if 1 eye began at level 2 while the other was at level 1, there was a higher probability that the second eye would progress to level 2, he explained. This was in keeping with investigators expectations. We were able to quantitate the risk of progression of 1 eye based on the severity of the fellow eye using statistical models. From a clinical perspective, this has important implications, Dr. Klein said. It enables a physician to tell a patient with some degree of confidence that if 1 eye is progressing, there is a high probability of the other following suit, he said, adding that there are exceptions, but this is what is probable. In most cases, if 1 eye is progressing, the other will do the same.

In addition, it provides a useful model for AMD investigators. It enables people who are studying those with AMD to provide estimates of what the probability of progression is, Dr. Klein said.

Editors note: Dr. Klein has no financial interests related to this article.

Contact information

Klein
: kleinr@epi.ophth.wisc.edu

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