Longitudinal change of retinal layer thickness in cognitively normal elderly subjects: population-based cohort study

Purpose: To identify longitudinal retinal layer thickness changes in normal eyes of cognitively healthy older participants. Methods: Post-hoc analysis was performed on 57 cognitively healthy older participants from the population-based KLoSHA and KLOSCAD cohort studies who underwent baseline and final optical coherence tomography (OCT) scans. The peripapillary retinal nerve fiber layer, subfoveal choroid, and average retinal layer thickness at four quadrant (nasal, temporal, superior, and inferior) points 1 mm, 2 mm, and 3 mm from the center of the fovea were measured. Results: Among the analyzed retinal layers, both the ganglion cell-inner plexiform layer (GCIPL) and the outer nuclear layer (ONL) at all 1, 2, and 3 mm points showed a statistically significant decrease in thickness at the final visit compared to baseline. The annual decrease rates were -1.2 μm/year at 1 mm (total -6.6%), -1.3 μm/year at 2 mm (total -8.4%), -1.1 μm/year at 3 mm (total -9.7%) for GCIPL; -0.6 μm/year at 1 mm (total -4.2%), -0.5 μm/year at 2 mm (total -3.9%), and -0.4 μm/year at 3 mm (total -4.1%) for ONL. Conclusions: Age plays a significant role in the reduction of GCIPL and ONL thicknesses in cognitively healthy elderly individuals.