Subthreshold Nanosecond Laser Treatment of Intermediate AMD without Reticular Pseudodrusen: Real-world Three-year Follow-up Study

Purpose Subthreshold nanosecond laser (SNL) has been proposed to reduce the risk of intermediate age-related macular degeneration (iAMD) progressing to late AMD. The phase 3 LEAD Study post-hoc analysis indicates a potentially large benefit from SNL treatment of eyes without reticular pseudodrusen. This real-world study reports the three-year outcomes of SNL treatment of iAMD without RPD. Methods An observational retrospective single-centre cohort study of all patients with iAMD, centre-involving very large soft drusen (≥250 μm diameter) without RPD, treated with SNL and with three-year follow up. The primary outcome measured was progression to late AMD; neovascular AMD (nAMD) or geographic atrophy (GA). Results There were 120 eyes of 64 patients. At baseline, the cohort had a high risk profile; drusen median area, volume and largest diameter were 0.70mm 2 (IQR: 0.20 to 1.50), 0.03mm 3 (IQR: 0.01 to 0.08) and 835μm (IQR: 446.50 to 1398.50) respectively; hyperreflective foci were present in 56.67%; and hyporeflective drusen cores in 25.83%. Eyes had a mean of 3.03 treatments. By three years, progression to late AMD occurred in 5.83% of eyes, all to GA. Visual acuity was stable or improved in 80% of eyes. Conclusion The three-year progression rate was low compared with published 36-month natural histories of iAMD without RPD. The progression rate was similar to the LEAD study SNL-treated group of iAMD without RPD. This study supports the hypothesis that SNL for iAMD without RPD may reduce progression to late AMD. Further investigation is warranted.