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We know from clinical experience that, even in the absence of glaucoma or other ocular diseases, the optic discs of most of our elderly patients look different from those of younger subjects and that it is sometimes difficult to differentiate them unequiv ocally from discs with early glaucoma. Histological studies have also shown that in healthy eyes, the number of optic nerve fibers declines with age and some ‐ though not all ‐ cross-sectional imaging studies have found changes in ONH topography with age. In this BJO paper, Harju et al. (679) have undertaken the long-term task of following-up healthy eyes over a decade in order to study the progressive changes in optic nerve head topography as measured by HRT.
Forty-three healthy volunteers were recruited among hospital staff and their friends; thirty-six of them were followed for an average 11 years (range: 7-13). No eyes developed glaucoma as defined by tonometric, perimetric and retinal nerve fiber layer criteria during the follow-up period, although one did develop exfoliation syndrome and another required cataract surgery.
HRT is sufficiently sensitive to detect age-dependent ONH changes
As could be expected, most HRT parameters showed significant changes over this period, indicating increased ONH cupping. In particular, cup area, C/D area ratio, rim area and mean cup depth were statistically different at the end of the follow-up as compared to baseline, while maximum cup depth and cup-shape measure also showed a significant correlation with age. Although, as the authors acknowledge, the sample size is small and not necessarily representative of the population at large, this indicates that HRT is sufficiently sensitive to detect age-dependent topographic ONH changes in healthy eyes, and that age-specific databases may facilitate differentiation between normal and glaucomatous optic nerve heads.