Dark adaptation testing has been shown to be better than visual acuity testing in diagnosing and staging AMD.
A characteristic of age-related macular degeneration (AMD) is the deterioration in the function of photoreceptor and retinal pigment epithelial (RPE) cells.
Neither supplementation with nutrients identified as AMD protective in Age-related Eye Disease Study (AREDS) I and II nor treatment with anti-vascular endothelial growth factor (VEGF) agents have been shown to counteract this deterioration.
The rapidity of adaptation to darkness provides a means of determining the health of photoreceptor and RPE cells in patients with atrophic AMD. Moreover, dark adaptation testing has been shown to be better than visual acuity testing in diagnosing and staging AMD.
For example, results of the AdaptDx (MacuLogix) test of dark adaptation in excess of 6.5 minutes predict future onset of AMD at least 3 years before a decrease in visual acuity is detectable. And the AdaptDx test has a sensitivity and specificity of 90% for predicting AMD.
Improvement in visual function has been reported in AMD patients taking capsules of the oral nutraceutical Longevinex, a supplement consisting of red wine solids (resveratrol) combined with 1,200 IU of vitamin D3, DNA repair nucleotides, and a cholesterol-lowering solubilizing agent, B cyclodextrin.
This combination has six times greater biological action than resveratrol alone and prevented legal blindness in a patient with a fast progressive form of exudative macular degeneration, polypoidal choroidal vasculopathy — in whom treatment with injected drugs had failed.
The effect of Longevinex on dark adaptation in 7 patients — or 14 eyes — with atrophic AMD was recently assessed by Stuart Richer, OD, PhD, FAAO, (pictured) director of the Ocular Preventative Medicine Eye Clinic at the Captain James A. Lovell Federal Health Care Center in North Chicago, Illinois.
Colleagues at this veterans’ hospital, at the Eye & Ear Infirmary of the University of Illinois at Chicago, and at the Chicago Medical School assisted with the study.
All patients studied had pre-existing vision loss. Moreover, their vision had not improved after using the AREDs antioxidant supplement formulated by the National Eye Institute. The age of the patients ranged from 64 to 89 years, though all but one of the patients studied were in their 80s.
The team conducted dark adaptation testing by using AdaptDx, an approved treatment by the U.S. Food and Drug Administration. During testing, this device removed rhodopsin from the back of the eye with a flash of light, then measured the time the eye takes to replenish rhodopsin levels.
Using this testing method, the team obtained baseline dark adaptation threshold, time, and fixation measurements for each patient. They then measured dark adaptation after patients took one capsule of Longevinex orally each morning for a period ranging from 5 weeks to 7 months.
After patients received treatment with Longevinex, testing revealed that 12 of 14 eyes improved in one or more dark adaptation parameters. The difference between expected versus actual results — in terms of worse dark adaptation versus stable or improved dark adaptation by eye — was statistically significant by chi-square testing at the level of P < 0.01.
The response to Longevinex was bilateral in 5 of 7 patients and, in one patient, was noted after 1 month of Longevinex therapy. Moreover, the investigators found a reduction in macular pathophysiology during spectral-domain optical coherence tomography in 3 of 7 patients and “profound multi-line improvements in visual acuity” in 4 of 7 patients.
“If this continues to be demonstrated in larger groups, we just may have, for the first time, a preventive for the most common cause of visual decline in senior Americans,” Richer said.
Richer added that combining AdaptDx screening with therapies such as Longevinex could alter the course of AMD.
Richer presented a poster, “Longevinex® improves human atrophic AMD photoreceptor / RPE mediated dark adaptation,” on the study on May 8, 2017, at the Annual Meeting of the Association for Research in Vision and Ophthalmology in Baltimore, Maryland.
A related review by members of the study team, “Age-related macular degeneration beyond the Age-related Eye Disease Study II,” appeared in the November, 2016, issue of Advances in Ophthalmology and Optometry.