Central corneal thickness in normal, glaucomatous, and ocular hypertensive eyes

Objective: To determine the relationship between central corneal thickness (CCT) and applanation intraocular pressure (IOP) in normal, glaucomatous, and ocular hypertensive eyes. Methods: One hundred nine subjects (184 eyes) were studied. Forty-eight patients (74 eyes) had glaucoma, 28 patients (51 eyes) had ocular hypertension, and 33 patients (59 eyes) were normal. Intraocular pressure as measured by applanation tonometry, refractive status, CCT, and axial length were measured for all subjects. Results: The CCT (mean+/-SD) of eyes with ocular hypertension was significantly greater (0.606+/-0.041 mm) than that of glaucomatous eyes (0.554+/-0.022 mm) (P<.001) or of normal controls (0.561+/-0.026 mm) (P<.001). There was no significant difference in CCT between normal and glaucomatous eyes (P=.40). The axial length (mean+/-SD) of eyes with ocular hypertension (23.54+/-1.34 mm) was not different compared with glaucomatous eyes (23.93+/-0.96 mm) (P=.13) or normal eyes (23.62+/-1.21 mm) (P=.83). There was no significant difference between the axial length for glaucomatous eyes compared with normal eyes (P=.18). Those eyes with glaucoma being treated with topical dorzolamide hydrochloride had a significantly increased CCT (0.560+/-0.025 mm) compared with those eyes with glaucoma not being treated with dorzolamide (0.551+/-0.20 mm) (P=.02). Conclusions: The mean CCT is increased in eyes with ocular hypertension when compared with normal or glaucomatous eyes, which confirms the findings of other investigators. Increased CCT may give an artificially high IOP measurement by applanation tonometry. The CCT must be considered when developing a treatment approach for patients with ocular hypertension.