Effect of Subthreshold Infrared Laser Treatment For Drusen Regression On Macular Autofluorescence In Patients WithAge-Related Macular Degeration

Abstract

BACKGROUND: Subthreshold laser therapy has been shown to cause drusen reduction. Using this method, visible laser burns are not created in the retina; presumably, the energy is absorbed by the retinal pigment epithelium (RPE) and stimulates reabsorption of drusen material, sparing photoreceptors from destruction. We hypothesized that autofluorescence (AF) changes would be visible after such treatment and might be sensitive to quantify RPE changes. METHODS: Twenty eyes of 13 patients with non-exudative age-related macular degeneration were studied. Forty-eight subthreshold infrared diode laser spots were applied as treatment to cause drusen regression. Before, immediately after, and 3 months after treatment, color fundus photography, fluorescein angiography (FA), and autofluorescence (AF) imaging were performed. Treated lesions were identified on overlay images of all three imaging methods. RESULTS: The averaged sensitivity of AF imaging compared with FA was 29.6+/-28.7% versus 10.2+/-12.2% (P=0.008) at the immediate posttreatment time point and 43.5+/-28.7% versus 33.8+/-26.5% (P=0.043) at the 3-month posttreatment time point, respectively. Reduction of drusen at 3 months correlated with the detection sensitivity of AF imaging at the immediate posttreatment time point (P=0.022). CONCLUSION: Immediately after subthreshold laser treatment, AF imaging was more sensitive to detect RPE changes than FA. This suggests that noninvasive AF imaging may allow prediction of the effect of subthreshold laser treatment and might be used to titrate treatment dose.