Zhichao Wu, Fred K. Chen, Lauren A. B. Hodgson1, Emily Caruso, Colin A. Harper, Sanjeewa S. Wickremashinghe, Amy C. Cohn1, Pyrawy Sivarajah, Nicole Tindill, Chi D. Luu, Robyn H. Guymer

Purpose: To examine the long-term effect of sub threshold nanosecond laser (SNL) treatment with the Retinal Rejuvenation Therapy (2RT®) device on disease progression in the early stages of age-related macular degeneration (AMD).

Methods: The LEAD study is a 36-month trial that included 292 participants with bilateral largedrusen who were randomised to receive either SNL or sham treatment in one eye at six-monthly intervals up to 30-months. At the end of the LEAD study, remaining participants at the two largest recruiting sites had an opportunity to enrol in a 24-month observational extension study (without further treatments). We examined the difference in progression to late AMD between treatment arms for these participants.

Results: Overall, the rate of progression over a 60-month period was not significantly different between the SNL and sham group (p = 0.098); a similar finding to the 36-month LEAD study. There was however, continued evidence of treatment effect modification based on the coexistence of reticular pseudodrusen (RPD) at baseline (adjusted interaction p = 0.007), where progression was significantly slowed with SNL treatment for those with- out coexistent RPD (p = 0.004), and no significant difference in progression with SNL treatment was observed for those with coexistent RPD (p = 0.239).

Conclusions: This 24-month observational extension study confirmed findings from the LEAD trial that overall, SNL treatment did not significantly reduce the rate of progression to late AMD. However, it also con- firmed a potential beneficial treatment effect in those without coexistent RPD over a longer follow-up period without additional treatment. These findings warrant further investigation of this intervention.