Falsely elevated intraocular pressure due to increased central corneal thickness

Purpose: To evaluate whether ocular hypertensive subjects have a higher cen tral corneal thickness than other individuals. Methods: In this prospective study, 48 subjects with ocular hypertension. 6 3 patients with open-angle glaucoma, 56 nonglaucomatous patients with diabe tes mellitus, and 106 control subjects were evaluated. Corneal thickness wa s measured by ultrasound pachymetry, and intraocular pressure was determine d by Goldmann applanation tonometry. Results: Central corneal thickness was significantly higher in the ocular h ypertensive subjects, mean +/-S.D., 592+/-39 mu m, than in the patients wit h glaucoma (536+/-34 mu m), the non-glaucomatous patients with diabetes mel litus (550+/-31 mu m), and the normal subjects (545+/-33 mu m), P<0.001, Th e three latter groups did not vary significantly in central corneal thickne ss, P>0.05. Conclusion: In some individuals with increased transcorneal measurements of intraocular pressure, the cornea is thicker than in subjects with normal i ntraocular pressure readings or patients with glaucoma. It suggests that in ocular hypertensive subjects, corneal pachymetry should be performed to ru le out an abnormally thick cornea as a reason for falsely high measurements of intraocular pressure.