Retinal thickness in eyes of older normal individuals and its implication for the diagnosis of glaucoma.

PURPOSE

Retinal thickness (RT) is a useful measurement for describing diseases that affect the thickness of the retina, such as glaucoma. Existing normative data are derived from relatively young individuals; however, glaucoma is most prevalent in older individuals. We therefore studied the RT in older normal individuals.

PATIENTS AND METHODS

Participants of the Baltimore Eye Study, persons accompanying patients, and staff were recruited and underwent visual field testing and a comprehensive eye examination by a glaucoma specialist. RT was measured with the retinal thickness analyzer (RTA, Talia Technology) and RT values in specific regions were derived using a custom-designed MatLab program.

RESULTS

One hundred and three eyes of sixty-two individuals were studied. Mean age was 61 years. Sixty-six percent were female and 82% were of European descent. The average mean deviation on visual field testing was 0.03 dB and the average pattern SD was 1.51 dB. The mean RT of the entire macula was 159+/-16 microm, and was lowest in the foveal pit and highest in the parafoveal annulus. The average distance from the foveal pit to the thickest point in the parafoveal annulus was 1240+/-138 microm. The mean RT of the entire macula was slightly less in older individuals (slope=-5.7 microm/10 y, P=0.02) but the height of the parafoveal annulus relative to the foveal pit, which is determined by the combined thickness of the parafoveal nerve fibers, ganglion cells, inner plexiform layer, and inner nuclear layer, did not vary with age (P=0.62).

CONCLUSIONS

Although the average RT of the entire macula was slightly thinner with increasing age, the height of the parafoveal annulus relative to the foveal pit did not change with age and would therefore seem to be a better marker of neuronal tissue health than the average RT of the entire macula.