To perform a cross-sectional study on the distribution of central corneal thickness and its association with intraocular pressure in an elderly population.

We measured central corneal thickness and intraocular pressure in 395 subjects (352 control subjects, 13 patients with ocular hypertension, and 30 patients with primary open-angle glaucoma) aged 55 years or more.

Mean central corneal thickness in the 352 control subjects was 537.4 μm (95% confidence interval [CI], 533.8 to 540.9 μm; range, 427 to 620 μm), with a maximal difference between eyes of 42 μm. There were no differences between sexes and no significant association with age. Linear regression analysis showed an increase of 0.19 mm Hg in intraocular pressure with each 10-μm increase in central corneal thickness (95% CI, 0.09 to 0.28 mm Hg). This association was similar in both eyes and in both sexes. The 13 patients with ocular hypertension had corneas a mean of 16.0 μm thicker (95% CI, -2.6 to +34.6 μm) compared with control subjects (P = .093); the 30 patients with primary open-angle glaucoma had corneas a mean of 21.5 μm thinner (95% CI, 8.8 to 34.1 μm) compared with control subjects (P = .001).

Mean central corneal thickness was similar to that found in clinical studies, was slightly higher in patients with ocular hypertension, and was significantly lower in patients with primary open-angle glaucoma. Intraocular pressure was positively related with central corneal thickness. Central corneal thickness may influence the division between normal and increased intraocular pressure at a simple cutoff point of 21 mm Hg.