Eyeworld

EW RETINA 86 February 2015 by Maxine Lipner EyeWorld Senior Contributing Writer New signs of trouble in diabetic eyes Adaptive optics detects early changes J ust because an early diabetic eye looks clear during traditional exam- ination does not mean that there is not damage already brewing, according to Ann E. Elsner, PhD, professor of optom- etry, Indiana University School of Optometry, recent associate dean of research at the School of Optometry, and director of the Borish Center for Ophthalmic Research, Bloomington, Ind. New study results published in the February 2014 issue of Biomedical Optics Express show that when early diabetic eyes were examined with adaptive optics, which heightens magnification, troubling damage to capillaries could be seen in some cases. Investigators were spurred to study diabetic eyes with this tech- nology for 2 reasons. The first was from the perspective of lowering the cost of healthcare, Dr. Elsner explained. "We have patients who are scheduled to come back year after year after being diagnosed with diabetes," she said. "Many of them don't come and the issue is like the boy who cried wolf." With adap- tive optics investigators hoped that they could spot those eyes that are incurring early damage. "The idea would be to make sure that people who have potential damage in the short term would get to the front of the line for eyecare," she said. Those who are doing well could be followed without the longer, more expensive specialized exam, she said. The second reason investigators undertook this was for the sake of basic science, she said. "There are so many questions that we don't know the answers to," Dr. Elsner said. "The chief one in my mind is once this damage starts happening, what, if any, is reversible?" Although it is known that better treatment and improving diet can slow leaking from blood vessels, what is not known is whether or not structural changes can be undone, she said. In the study, a laboratory-based confocal adaptive optics scanning laser ophthalmoscope built by lead investigator Stephen Burns, PhD, was used to view the retinas of those with non-proliferative diabet- ic retinopathy. Utilizing adaptive optics, investigators were able to get a highly magnified view of what was going on in the eye. This enabled investigators to examine 1 µm to 2 µm of retina for each pixel on the device, she said. Troubling early signs When investigators viewed the retinal blood vessels in early dia- betic eyes that seemed quiet, they saw damage in some cases that they were not expecting. "What kept me from sleeping the first night I saw it was the fact that there were knots in capillaries that looked like knots in yarn," Dr. Elsner said. "Everyone knows you have micro-aneurysms, so seeing those was expected—what we didn't expect was to see tangles of capillaries." Investigators found that these tended to be looped instead of straight. "The capillaries were longer than they should be and doubled back on themselves," Dr. Elsner said. "It looked like little knots." While not everyone had this result, Dr. Elsner was taken aback by those who did. "I was not prepared for that in a young person in whom you couldn't see anything like that in a clinical exam or the wide-field image," she said. "It looked like a decent eye, but the problem was the capillaries weren't well-perfused, and they had knots in them." In addition, it looked as though some of the other capillaries were plugged up, causing the retina to become ischemic, Dr. Elsner said. "If I found that in someone who already had proliferative retinopa- thy and was facing laser treatment, I wouldn't be surprised," she said. "But when we looked at these eyes, they looked blank with ordinary blood vessels at the ordinary magnification." Also unexpected, investigators saw a proliferation of tiny exudates Even when eyes of a diabetic patient seem quiet, closer inspection may show loops, knots, or tangles of capillaries. Source (all): Stephen Burns, PhD

• Cover