Subthreshold Nanosecond Laser in Age-Related Macular Degeneration: Observational Extension Study to the LEAD Clinical Trial

Abstract

Purpose : To evaluate the long-term effect of subthreshold nanosecond laser (SNL) treatment on progression to late age-related macular degeneration (AMD).

Methods : The Laser Intervention in the Early Stages of AMD (LEAD) study is a 36-month trial where 292 participants with bilateral large drusen were randomized to receive SNL or sham treatment in one eye at 6-monthly intervals up to 30-months. After the completion of the LEAD study, the two largest recruiting sites (who recruited 212 participants) offered remaining participants an opportunity to enrol in a 24-month observational extension study, with no further treatments performed. The difference in the time to develop late AMD between those randomized the SNL or sham treatment for participants at these two sites (referred to as the “extension study”) was examined.

Results : Overall, there was no significant difference in rate of progression over a 60-month period in those randomized to the SNL compared to sham group (adjusted hazard ratio [HR] = 0.63; 95% confidence interval [CI] = 0.36 to 1.09; P = 0.098), being a similar finding seen in the 36-month LEAD study. However, there continued to be evidence of treatment effect modification based on the coexistence of reticular pseudodrusen at baseline (RPD; adjusted interaction P = 0.007). Namely, progression was significantly slowed with SNL treatment for those without coexistent RPD (adjusted HR = 0.34; 95% CI = 0.16 to 0.71; P = 0.004), but it was not significantly different for those with RPD (adjusted HR = 1.81; 95% CI = 0.67 to 4.88; P = 0.239).

Conclusions : A 24-month observational extension study to the LEAD trial confirmed that SNL treatment did not significantly reduce the overall rate of progression to late AMD. However, the persistence of a potential beneficial treatment effect in those without coexistent RPD over a longer follow-up duration of 24 months without additional treatment is encouraging. These findings provide further justification for future trials to examine the potential value of SNL treatment for slowing progression in the early stages of AMD.

This is a 2021 ARVO Annual Meeting abstract.