The average thicknesses of various retinal layers in the central foveola exhibit distinct age-related variations, according to research published in Experimental Eye Research. Secondary findings revealed sex-related associations in individuals older than 55 years.
Investigators assessed the age- and sex-related variations of the mean thicknesses of various retinal layers at the central foveola. They used spectral-domain optical coherence tomography (SD-OCT) to measure the thicknesses of the retinal tissue, retinal pigment epithelium (RPE), myoid zone (MZ), and ellipsoid zone (EZ), and the lengths of the photoreceptor inner segments (PIS) and photoreceptor outer segments (POS). In total, they used images from 2944 healthy eyes of 1990 participants (age range, 5-85).
The researchers noted that the maximum mean lengths of photoreceptors is achieved between 5 and 36 years of age and decreases between 36 and 85 years. MZ thickness increases between 5 and 21 years and plateaus at 36 years before thinning. EZ thickness, however, does not change across a lifespan. The team determined that the shortening of photoreceptors in the elderly is due to decreased POS length and MZ thickness, and not due to EZ thickness.
The investigators also observed sex-related differences in 5 parameters for individuals aged between 55 and 85 years including mean thicknesses of retinal tissue, MZ, outer nuclear layer, and the horizontal layer of Müller cell cone, and mean length of the PIS.
“The mean thicknesses of individual retinal layers at the central foveola show distinct age-related variations,” according to the researchers. “Relatively independent thickness variations of distinct retinal layers are also indicated by the weak correlations which we found in comparisons of the thicknesses of various retinal layers.”
Limitations of the study include a lack of correction for possible dependencies on refraction and axial length and failure to measure intraocular pressure, which could have impacted the thickness parameters measured.
Bringmann A, Barth T, Wiedemann R, Wiedemann P. Age- and sex-related variations of individual retinal layer thickness in the foveal center of healthy eyes. Exp Eye Res. Published online March 17, 2022. doi:10.1016/j.exer.2022.109038.