Central corneal thickness measurements in patients with normal tension glaucoma, primary open angle glaucoma, pseudoexfoliation glaucoma, or ocular hypertension

Background/aims-Recent studies have revealed patients with ocular hypertens ion to have thicker than normal central corneas and those with normal tensi on glaucoma to have thinner than normal ones, as determined by ultrasonic p achymetry. Since corneal thickness measurements and applanation tonometric estimates of intraocular pressure (IOP) correlate positively, monitoring of the former parameter have served as the basis for adjusting readings perta ining to the latter, with the consequence that many patients have had to be reclassified. With a view to validating these pachymetric studies, the cen tral corneal thickness was determined in patients with normal tension glauc oma, primary open angle glaucoma, pseudoexfoliation glaucoma, or ocular hyp ertension, as well as that of normal subjects, using optical low coherence reflectometry, which is a new and more precise method than ultrasonic pachy metry. Methods-34 patients with normal tension glaucoma, 20 with primary open angl e glaucoma, 13 with pseudoexfoliation glaucoma, and 12 with ocular hyperten sion, together with 21 control subjects, were included in this observationa l, concurrent case-control study. One eye per individual was randomly selec ted for investigation. IOP was measured by Goldmann applanation tonometry a nd central corneal thickness by optical low coherence reflectometry. Results-Central corneal thickness was significantly higher (p less than or equal to0.001) in patients with ocular hypertension than in normal individu als or in subjects with either normal tension glaucoma, primary open angle glaucoma, or pseudoexfoliation glaucoma, there being no significant differe nces between the latter four groups. Patients with ocular hypertension were also significantly younger (p less than or equal to0.003) than those withi n any of the three glaucomatous groups. Conclusion-This study confirms that a significant number of patients with o cular hypertension have normal IOPs after the appropriate adjustments have been made for deviations from normal in their central corneal thickness. Th e accurate measurement of this latter parameter is important not only for i ndividual patient care, in permitting more precise estimations of IOP, but also for clinical studies, in assuring a more reliable classification of su bjects.