Purpose: A sensitive endpoint is required for clinical trials evaluating preventative therapies for early age-related macular degeneration (AMD). Dark adaptation (DA) is a sensitive marker of AMD and has been proposed as a potential endpoint. This study evaluated whether significant changes in DA speed could be detected in participants with early to intermediate AMD at 12 months following baseline DA measurement.
Methods: Dark adaptation, visual acuity (VA), and fundus photography were obtained at baseline and at 6 and 12 months in 26 subjects with AMD and in 6 subjects with normal retinal health. Disease severity was assessed by the Nine-Step Age-Related Eye Disease Study AMD severity scale.
Results: At 12 months, significant progression of DA impairment occurred in 5 of 26 (19%) participants with AMD. None of the participants with AMD exhibited a significant worsening of fundus grade or decrease of acuity related to disease progression. The normal group exhibited stable DA and VA during the observation period.
Conclusions: Significant worsening of DA was observed in 19% of subjects with AMD in 12 months of observation, despite stable VA and fundus appearance. This study suggests that DA may be a suitable functional endpoint for early clinical studies evaluating novel treatments for early to intermediate AMD.