[Relationship between the retinal nerve fiber layer thickness and the effect of aging in normal eyes]

We studied the correlation between the thickness of the retinal nerve fiber layer and the role of age in 155 normal eyes of 83 subjects without significant ocular diseases. Subjects with a refractive error exceeding +/- 5 diopters were excluded. We divided the peripapillary area into four quadrants: superior (S), inferior (I), temporal (T), and nasal (N). We measured peripapillary retinal nerve fiber layer thickness (NFLT) in these four quadrants and in the total area (T(o)) using a confocal scanning laser polarimeter (Nerve Fiber Analyzer), and determined the correlation coefficients. The retinal nerve fiber layer thickness of the total area and of the four quadrants was not significantly associated with an increase in age. Since changes in the thickness were small in the nasal and temporal quadrants, we measured the relative ratios of the thickness in each quadrant to that in the nasal and temporal quadrants. The ratio of the total area to the nasal quadrant (T(o)/N), the superior to the nasal quadrant (S/N), the inferior to the nasal quadrant (I/N), the total area to the temporal quadrant (T(o)/T), the superior to the temporal quadrant (S/T), and the inferior to the temporal quadrant (I/T) was significantly associated with an increase in age. Multiple comparison in each age group revealed no age-related significant decreases in any of the parameters. These findings suggest that these parameters may reflect the degree of aging in normal eyes, but age-related abnormality in the retinal nerve fiber layer thickness may be small.