Age-associated changes in the retinal nerve fiber layer and optic nerve head

Optical coherence tomography (OCT) measures of the retinal nerve fiber layer (RNFL) thickness and neuroretinal rim (NRR) parameters are often used as a surrogate for retinal ganglion cell content. The purpose of this study was to investigate the relationship between these morphological measures and the aging effects on these structures. One hundred thirteen healthy individuals, aged 19 to 76 years, with no prior history of retinal of optic nerve head pathology were recruited. A circumpapillary and radial OCT scan centered on the optic nerve head (ONH) was used for data analysis. Transverse scaling was calculated for each subject using measures from optical biometry. Custom algorithms were used for morphological analysis of the ONH NRR and RNFL that included quantification of major retinal vascular contribution. There was a significant age-related loss of RNFL thickness (-0.23 μm/y, R(2) = 0.24, P < 0.01), major retinal vascular contribution (-0.03 μm/y, R(2) = 0.07, P = 0.01, neural rim volume (NRV, -0.004 mm(3)/y, R(2) = 0.15, P < 0.01), and minimum rim width (MRW, -1.77 μm/y, R(2) = 0.23, P < 0.01) before, and after, incorporating the Bruch's membrane opening size (sMRW, -1.86 μm/y, R(2) = 0.22, P < 0.01). When normalized, the rates of change for ONH NRR parameters (NRV, 0.69%/y and sMRW, 0.50%/y) exceeded that of RNFL thickness (0.19%/y, P < 0.01). Although both RNFL and ONH NRR parameters contain axons of retinal ganglion cells, there are differences in age-related changes in these measures that should be considered in clinical application.