In Vivo Human Cone Photoreceptor Inner Segment Diameter Database Using Adaptive Optics Retinal Imaging

To establish an in vivo database of human cone photoreceptor inner segment diameter evaluated across the lifespan.

Non-confocal split detection adaptive optics (AO) imaging was performed in 28 eyes of 28 healthy subjects (14 females and 14 males; 45.1 ± 20.7 years, ranging from 12-84 years). Cone photoreceptor inner segments were semi-automatically segmented and cone diameters measured from the AO images across eccentricities ranging from 1.0 to 6.0 mm temporal to the fovea. A linear mixed-effects model was used to assess the relationship between cone diameter and sex as well as cone diameter and age.

Cone photoreceptor inner segment diameter increased with increasing eccentricity (n = 9350 segmented cones), from an average of 5.0 µm (eccentricity: 1.0 mm) to 7.8 µm (6.0 mm). Overall, cone diameter in females was slightly greater (by an average of 5%) than cone diameter in males across most eccentricities measured. The differences in cone diameter between females and males could not be accounted for by differences in axial length or age. In addition, cone diameters in younger subjects were generally larger than those from older subjects.

In vivo measurements of human cone photoreceptor inner segment diameter across the lifespan are necessary for future comparisons with data from age-related disease. Statistically significant differences due to both age and sex were observed.