CAPT: Laser treatments do not prevent vision loss in patients with large drusen

Low-intensity laser treatments appear to be ineffective in preventing vision loss or slowing the onset of late age-related macular degeneration in eyes with large drusen, a long-term NEI-sponsored study found.

Previous reports have shown that laser treatment can reduce the extent of large drusen and have suggested that such laser treatments may have a beneficial effect on vision. However, the studies have included small numbers of patients observed for varying periods, often with less than desirable follow-up, according to the authors of the new study.

The Complications of Age-Related Macular Degeneration Prevention Trial (CAPT), sponsored by the National Eye Institute, examined the efficacy of low-intensity laser treatment in 1,052 patients enrolled at 22 clinical centers in the United States. At baseline, all patients had bilateral large drusen, defined as greater than 125 µm in diameter, and visual acuity better than 20/40 in both eyes.

One eye of each patient was treated with a laser, usually 514 µm argon green, while the contralateral eye served as an untreated control. The initial laser protocol specified 60 barely visible burns — 15 burns per quadrant — applied in a grid pattern within an annulus between 1500 µm and 2000 µm from the foveal center. At 12 months, any eyes in the treatment group with a significant amount of remaining drusen were re-treated with 30 burns.

At 5 years' follow-up, the investigators found that 188 (20.5%) treated eyes and 188 (20.5%) untreated eyes had lost three lines of vision or more from baseline (P = 1.0). The change in visual acuity was strongly associated with the development of late AMD but not with treatment group, the study authors said.

The cumulative 5-year incidence of late AMD was 19.7% for treated eyes and 20.4% for untreated eyes. The 5-year incidence of choroidal neovascularization was 13.3% for both treated and untreated eyes (P = .95), and the 5-year incidence of geographic atrophy was 7.4% for the treated eyes and 7.8% for the untreated eyes (P = .64), according to the study authors.

"This is an important study because after 35 years of inconsistent results from preventive laser treatment trials, we now know that this approach does not seem to stop vision loss from AMD. Doctors using this technique should reconsider its use in patients with good vision," NEI Director Paul A. Sieving, MD, PhD, said in a press release announcing the study results.

Dr. Sieving noted that the only established way for patients with large drusen to decrease their risk of vision loss is to take daily high-dose antioxidant vitamins and minerals, such as those used in the NEI-supported Age-Related Eye Disease Study. This study showed that such supplements taken daily could reduce the risk of progression to late AMD by 25%.

The results of the CAPT study are published in the November issue of Ophthalmology.