Long-term effect of laser treatment for dry age-related macular degeneration on choroidal hemodynamics

Abstract

Purpose: To determine whether laser treatment applied according to the complications of age-related macular degeneration prevention trial (CAPT) has an effect on the choroidal circulation.

Design: Randomized controlled trial.

Methods: This study included 30 CAPT patients with bilateral drusen. Laser Doppler flowmetry was used to measure relative choroidal blood flow (Ch(flow)) in the fovea. Measurements were obtained through dilated pupils in both eyes of each patient before photocoagulation was applied in one eye. Measurements were repeated at three months (30 patients) and 28 months (23 patients).

Results: Average Ch(flow) at baseline, three months, and 28 months was 7.2 +/- 2.1 (+/-1 SD), 7.3 +/- 2.5, and 6.8 +/- 2.7 arbitrary units (AU) in the control eyes and 6.6 +/- 1.6, 7.0 +/- 2.3, and 7.8 +/- 3.0 AU in the treated eyes. In comparison to control eyes, there was no significant change in Ch(flow) in the treated eyes at three months after treatment. At 28 months, however, there was a 5.6% drop in Ch(flow) in control eyes and an 18.2% increase in Ch(flow) in treated eyes from baseline. The average difference of 23.8% between the percentage changes in Ch(flow) observed in the control and treated eyes was statistically significant (paired two-tailed Student t test; P = .05).

Conclusions: Our results suggest an increase in choroidal blood flow 28 months after laser treatment according to the CAPT protocol. This increase may play a role in the mechanism leading to the disappearance of drusen after photocoagulation. Whether removal of drusen after photocoagulation is beneficial to the patients is not known at this time.