gms | German Medical Science

Background: To determine the efficacy and safety of sub-threshold nanosecond laser (SNL) treatment in intermediate age-related macular degeneration (iAMD) to slow progression to late AMD.

Methods: 292 participants with bilateral drusen >125 um within 1500 um of the fovea, monocular best corrected visual acuity (BCVA) 20/40 or better were randomized to receive SNL (twelve laser or sham spots) 6-monthly for 36-months. The primary outcome was time to late AMD as defined by multimodal imaging (a combined endpoint of choroidal neovascularization, geographic atrophy or atrophy as defined on optical coherence tomography) in the study eye using the full intent to treat (ITT) cohort. The exploratory outcome measures were the rate of change in best-corrected visual acuity (BCVA), low luminance visual acuity (LLVA), microperimetric mean sensitivity (MS), drusen volume in the study and non-study eyes.

Results: Overall, progression to late AMD was non-significantly slowed with SNL compared to sham treatment (adjusted hazard ratio [HR] 0·61, 95% CI 0·33–1·14). Slowing was more apparent for participants without coexistent reticular pseudodrusen (RPD) at baseline (adjusted HR 0·23, 95% CI 0·09–0·59), but participants with RPD had an increased progression rate (adjusted HR 2·56, 95% CI 0·80–8.18; adjusted interaction p=0·002). The rate of BCVA decline was slightly higher for participants in the SNL compared to sham group in the study eye (-0.8 letters/year faster; P<0.001), but not the non-study eye (0.1 letters/year; P=0.628). There was no significant difference between study groups in the rate of change of LLVA, microperimetric MS and drusen volume in the study or non-study eyes, (all P≥0.167).

Conclusions: These findings provide evidence for the need for further trials of SNL as a potential early intervention for the early stages of AMD.