Central corneal thickness in the European Glaucoma Prevention Study

To measure central corneal thickness (CCT) within the participants of the European Glaucoma Prevention Study (EGPS). This study was designed to test if lowering intraocular pressure (IOP) by means of dorzolamide is able to prevent or delay conversion from ocular hypertension to glaucoma. DESIGN: Randomized, double-masked, controlled, observational clinical trial. PARTICIPANTS: Eight hundred fifty-four of 1077 ocular hypertensive participants within the EGPS were investigated. Four hundred twenty-nine patients were treated with dorzolamide and 425 patients received placebo. INTERVENTION: Treatment with dorzolamide or placebo (the vehicle of dorzolamide) in 1 or both eyes. MAIN OUTCOME MEASURES: Central corneal thickness as measured by ultrasound pachymetry (DGH-500 Pachette; DGH Technologies, Exton, PA). The CCT measurements were obtained in the morning before measuring IOP. Five measurements were taken from each eye of each patient within 5 minutes of application of anesthetic eye drops. RESULTS: Mean CCT was 572.6+/-37.4 microm (range, 458.5-695.6 microm). The CCT was higher in younger patients, male patients, and diabetic patients. Mean CCTs for the 429 patients receiving dorzolamide were 574.2+/-38.48 microm (range, 458.5-695.6 microm) and 571.0+/-36.21 microm (469.7-690.1 microm) for the 425 patients receiving placebo (P = 0.205). Central corneal thickness did not correlate with refraction, baseline IOP, or systemic hypertension. CONCLUSION: Central corneal thickness measurements within the EGPS were greater than those reported in other studies of normal eyes without ocular hypertension. Larger CCT measurements correlated with male gender, younger age, and diabetes