Effect of subthreshold nanosecond laser on retinal structure and function in intermediate age-related macular degeneration

Background Subthreshold nanosecond laser (SNL) treatment has been studied as a potential intervention in intermediate age-related macular degeneration (iAMD). This study investigated the effect of 100 SNL treatment spots on retinal structure and function. Methods A prospective single-arm interventional pilot study. SNL treatment was delivered as 100 spots around the retinal vascular arcades of the study eye (worst visual acuity) in a single session in subjects with iAMD. Multimodal retinal imaging and dark-adapted chromatic perimetry were performed at baseline and at 0.5, 3, 6 and 12 months post treatment. Post treatment changes in best corrected visual acuity (BCVA), retinal thickness, relative ellipsoid zone reflectivity (rEZR) and rod-mediated functional parameters were compared to baseline. Results Twenty-one subjects with iAMD were recruited. SNL treatment was associated with an increase in retinal thickness (p = 0.008) and decrease in rEZR (p < 0.001) at 2 weeks post laser. Recovery of retinal thickness and rEZR was observed at the 3-month post laser visit. A gradual improvement in BCVA was observed after laser treatment. The mean change in BCVA between baseline and 12-month visit was +1.9 +/- 3.3 letters for the SNL treated eyes, compared to -0.4 +/- 3.0 letters for the fellow eyes (p = 0.027). Rod-mediated function improved at 3 months post laser (p < 0.001) and returned to the baseline levels at 12 months post treatment. Conclusions A single treatment with 100 SNL spots causes a short-term change in retinal structure and improvement in retinal function that are apparent at 3 months post treatment.