Prescribing for patients with age-related macular degeneration

Baltimore-Knowing when and how to prescribe vision enhancement in patients with neovascular or wet age-related macular degeneration (AMD) is the key to achieving the greatest possible visual improvements in the impaired population, said Judith E. Goldstein, OD, FAAO.

"It can lead to exudation, disruption of photoreceptors, and ultimately retinal scarring," she said. "Neovascular age-related macular degeneration (NV AMD) affects both eyes in 50% of the population, so you can expect that at least half of individuals with the neovascular form will experience vision-related problems with daily activities over their lifetime."

Historically, treatment for NV AMD has had less than satisfactory outcomes until the advent of anti-angiogenic therapy, which has revolutionized the field over the past 5 years, Dr. Goldstein said.

"The timing of these treatments has changed the way we think of neovascular AMD," she said. "Originally with subfoveal choroidal neovascularization, focal photocoagulation was often performed once or twice (depending on recurrences of new blood vessel growth), a macular scar was created and patients were left with vision in the 20/100 to 20/200 range.

"Macular translocation surgery consisted of one surgical event, and again, patients were left with severe visual impairment," Dr. Goldstein continued. "The development of photodynamic therapy (PDT) incurred an increase in the number of treatments and better visual results than prior therapies, however patients were still receiving, on average, only three treatments over a period of 12 months.

"But with use of anti-angiogenic therapy, which includes agents such as bevacizumab (Avastin, Genentech) and ranibizumab (Lucentis, Genentech), treatment for neovascular AMD has completely changed the management of the disease," she said. "Stabilization of visual acuity is common and even improvement in some cases occurs.

"The treatment regimen, however, typically requires monthly injections for an unknown, indefinite period of time, and can be thought of as chronic therapy," Dr. Goldstein said.

Prescribing for patients

Before prescribing any type of visual enhancement for these patients, there are several considerations to explore, including how long after therapy to wait before prescribing glasses or other forms of vision enhancement. To better answer these questions, Dr. Goldstein reviewed results from two recent studies that shed light on the timeframe of visual improvement and stabilization in patients receiving anti-angiogenic treatment.

The first of these is the Anti-VEGF Antibody for the Treatment of Predominantly Classic Choroidal Neovascularization in AMD (ANCHOR) study. Researchers evaluated 423 patients with classic choroidal neovascular disease.¹ The primary endpoint was a loss of <15 letters. In the verteporfin (Visudyne, Novartis) or PDT group, 64% of patients were able to maintain a <15-letter loss, as compared with 96% of patients in the ranibizumab 0.5% group.

"What was exciting about this study was that 40% of patients in the ranibizumab group gained ≥ 15 or more letters-equivalent to a three line acuity improvement-while only 5% of the patients in the PDT group reached this threshold," Dr. Goldstein said.

"With ranibizumab, longitudinally, 7 days after injection, patients gained on average 5 letters on the EDTRS chart. Between 2 to 6 months, visual acuity levels off, and patients gain on average 10 letters," she said. "There is frequent objective and subjective fluctuation in vision and when these patients come to you, they'll tell you that their vision changes day to day.

"Some of this may be secondary to the underlying disease process and part of this may be due to the drug therapy," she added. "But what the data tells us is that between 2 and 6 months, they will achieve the maximum levels of visual acuity that they will ever have, under most circumstances."