Eyeworld

A new tool is cutting the amount of time these tests typically take D ark adaptation—the recov- ery of vision when going from bright light to dark- ness—is relatively quick in healthy eyes, but can be incredibly slow in eyes with age-re- lated macular degeneration (AMD). In early AMD, rod function begins to deteriorate before cone function; upon the transition to advanced AMD, cone dysfunction becomes apparent, which leads to the classic deterioration in visual acuity. "Rods are affected earlier in the disease and more severely through- out the disease than cones. That's why we're interested in testing night vision," said Greg Jackson, PhD, chief science officer of MacuLogix, Hummelstown, Pa. Dr. Jackson is the principal inventor of the company's AdaptDx dark adaptometer. "Dark adaptation is simply the recovery of visual sensitivity as you go from a lit environment to a dark environment. Dark adaptation mea- sures the speed of that transition," he said, and the quicker the transi- tion, the better. While there are numerous ways to measure dark adaptation, using a rapid measurement of dark adaptation, an eye that can adapt in less than 6.5 minutes is normal; any longer than that indicates a problem, Dr. Jackson said. A "characteristic deficit of early AMD is impaired night vision," he said, and function may be severely impaired even though there are few drusen or structural lesions. Macrophages have a key role in clearing cholesterol from the eye, but they naturally become less efficient with age. So while small drusen may also be considered a normal part of aging, larger drusen are indicative of retinal disorders. Cholesterol impairs the ability of the by Michelle Dalton EyeWorld Contributing Writer Measuring dark adaptation Patient compliance For any of the anti-VEGFs to be effective, patients must be willing to return to the office on a regular ba- sis. Dr. Boyer finds that compliance with these injections varies depend- ing on the condition being treated. "The macular degeneration pa- tients are very compliant once they get an improvement in vision," he said. "If they don't get an improve- ment in vision, they start to ques- tion whether it's worthwhile getting these injections." Meanwhile, the diabetic pa- tients tend to have a more difficult time returning to the office because they have to take time off work, he said. "It's much more difficult to keep them on a monthly or 6-week treatment schedule." Dr. Natarajan finds that the majority of patients at his center do return for treatment regularly. "We have a counselor explain to them the need and the benefit," he said. The hospital has worked on educating patients here, giving Amsler charts to everyone. "We have created the first hanging Amsler grid garden in the world in our hospital," he said. This helps to draw attention to the importance of retinal health. Going forward, Dr. Natarajan believes that either longer-acting agents or alternative ways of admin- istering the anti-VEGF medication are needed. "I think we need a drug that will be long-lasting or [one] where the dosage is released periodically," he said. While it sounds like science fiction, this could potentially be done with nanotechnology, where a laser is used to release more of the drug each month. EW Editors' note: Dr. Boyer has financial interests with Genentech and Regeneron. Drs. Natarajan and Warren have no related financial interests. Contact information Boyer: vitdoc@aol.com Natarajan: prof.drsn@adityajyoteyehospital.org Warren: kwarren@warrenretina.com A wide view continued from page 79

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