Falsely elevated intraocular pressure due to increased central corneal thickness

Purpose: To evaluate whether ocular hypertensive subjects have a higher central corneal thickness than other individuals. Methods: In this prospective study, 48 subjects with ocular hypertension. 63 patients with open-angle glaucoma, 56 nonglaucomatous patients with diabetes mellitus, and 106 control subjects were evaluated. Corneal thickness was measured by ultrasound pachymetry, and intraocular pressure was determined by Goldmann applanation tonometry. Results: Central corneal thickness was significantly higher in the ocular hypertensive subjects, mean +/-S.D., 592+/-39 mu m, than in the patients with glaucoma (536+/-34 mu m), the non-glaucomatous patients with diabetes mellitus (550+/-31 mu m), and the normal subjects (545+/-33 mu m), P<0.001, The three latter groups did not vary significantly in central corneal thickness, P>0.05. Conclusion: In some individuals with increased transcorneal measurements of intraocular pressure, the cornea is thicker than in subjects with normal intraocular pressure readings or patients with glaucoma. It suggests that in ocular hypertensive subjects, corneal pachymetry should be performed to rule out an abnormally thick cornea as a reason for falsely high measurements of intraocular pressure.