Ageing and glaucoma progression of the retinal nerve fibre layer using spectral‐domain optical coherence tomography analysis

Purpose: To compare the effects of ageing and glaucoma progression on the thickness of the circumpapillary retinal nerve fibre layer (cpRNFL) and to evaluate the performance of a set of optical coherence tomography (OCT) progression analyses. Methods: The cpRNFL was measured twice by OCT at each of two visits made 10 years apart in 69 healthy individuals and 49 glaucoma patients. Both visits also included Humphrey 24-2 SITA standard testing. The change in cpRNFL thickness was analysed by linear regression, and a sub-analysis was performed on glaucoma patients with a perimetric mean deviation better than −10 dB at the first visit. The proportion of individuals whose OCT progression analyses indicated progression was also evaluated for the same groups. Results: The average cpRNFL thickness deteriorated by a mean of −0.16 μm/year in the healthy cohort, increased by 0.03 μm/year in the glaucoma cohort, and deteriorated by −0.24 μm/year in eyes with less severe glaucoma; there were no statistically significant differences between the groups. For 17 (30%) of 56 healthy individuals, at least one of the three different OCT progression analyses incorrectly indicated progression. Conclusions: No significant differences in change of cpRNFL thickness between visits were found when comparing healthy subjects with glaucoma patients. Also, further cpRNFL thinning was not observed in glaucomatous eyes in which at least one-third of the visual field had been lost. The OCT progression analyses generated a relatively high proportion of false positives. Using OCT for glaucoma follow-up may not be entirely straightforward.