Central corneal thickness determined with optical coherence tomography in various types of glaucoma

AIMS: To evaluate central corneal thickness determined by optical coherence tomography (OCT) in various types of glaucoma, and its influence on intraocular pressure (IOP) measurement. METHODS: Central corneal thickness (CCT) was determined by using OCT in 167 subjects (167 eyes). 20 had primary open angle glaucoma (POAG), 42 had low tension glaucoma (LTG), 22 had ocular hypertension (OHT), 10 had primary angle closure glaucoma (AC), 24 had pseudoexfoliation glaucoma (PEX), 13 had pigmentary glaucoma (PIG), and 36 were normal. RESULTS: CCT was significantly higher in ocular hypertensive subjects (593 (SD 35) microm, p <0.0001) than in the controls (530 (32) microm), whereas patients with LTG (482 (28) microm, p < 0. 0001), PEX (493 (33) microm, p <0.0001), and POAG (512 (30) microm, p <0.05) showed significantly lower readings. There was no statistically significant difference between the controls and patients with PIG (510 (39) microm) and AC (539 (37) microm). CONCLUSIONS: Because of thinner CCT in patients with LTG, PEX, and POAG this may result in underestimation of IOP, whereas thicker corneas may lead to an overestimation of IOP in subjects with OH. By determining CCT with OCT, a new and precise technique to measure CCT, this study emphasises the need for a combined measurement of IOP and CCT in order to obtain exact IOP readings.