Longitudinal Change in Retinal Nerve Fiber Layer Thickness and Intraocular Pressure in Young Adults

Age-related changes in glaucoma endophenotypes have been described thoroughly, yet, there are limited data on the normal age-related changes in young adults. This study profiles the 8-year longitudinal change in peripapillary retinal nerve fiber layer (pRNFL), intraocular pressure (IOP), and central corneal thickness (CCT) in young adults.

A community-based cohort of young adults from the Raine Study underwent eye examinations that included optical coherence tomography of the optic disc, tonometry, and pachymetry when they were 20 and 28 years old. The main outcome measures were the changes in pRNFL thickness, IOP, and CCT over 8 years, adjusted for sex, ethnicity, and other potential confounders.

A total of 693, 712, and 680 participants were included in the pRNFL, IOP, and CCT analyses, respectively. Over the 8 years, the global pRNFL reduced from a mean of 100.6 ± 9.3 to 97.9 ± 9.4 µm, at an average rate of 0.27 µm/year (95% confidence interval [CI], 0.24-0.30). Sectoral pRNFL similarly thinned by 0.06 to 0.38 µm/year, but this thinning was not statistically significant at the superotemporal and inferonasal sectors. IOP decreased and CCT increased between 20 and 28 years old, at an average rate of 0.18 mm Hg/year (95% CI, 0.15-0.20) and 0.18 µm/year (95% CI, 0.10-0.27), respectively.

During the third decade of life, there is a decrease in pRNFL thickness and IOP in healthy adults.

The current study findings will enable clinicians to differentiate potential pathological change from normal age-related variations in these measures.