Correlation between corneal and scleral thickness in glaucoma

PURPOSE: To assess the correlation between central corneal thickness (CCT) and anterior scleral thickness (ST) in patients of primary open-angle glaucoma (POAG), normal tension glaucoma (NTG), and ocular hypertension (OHT). PATIENTS AND METHODS: Consecutive patients with OHT, POAG, NTG, and normal individuals were recruited. CCT was measured by ultrasonic pachymetry, whereas ST was measured using ultrasonic biomicroscopy at the temporal quadrant, 2'mm posterior to the scleral spur. Investigators were masked to the diagnosis and CCT/ ultrasonic biomicroscopy data. Correlation between mean CCT and ST was analyzed. RESULTS: One hundred and twenty-four subjects (31 with OHT, 31 with POAG, 31 with NTG, and 31 normal individuals) were enrolled. The CCT (OHT 548.06±30.45'μm; POAG 519.39±42.95'μm; NTG 505.81±27.23'μm; controls 529.90±43.40'μm) was found to be thicker in patients with OHT than POAG (P=0.004) or NTG (P<0.01). There was also a difference in CCT between NTG and control eyes (P=0.012). The ST (OHT 755.03±69.58'μm; POAG 738.45±66.83'μm; NTG 708.74±71.58'μm; controls 724.45±73.27'μm) was thicker in the OHT group than in NTG patients (P=0.012). No significant difference in ST was found among other groups. Among subgroups, the correlation between CCT and ST was found only among the patients with NTG (r=0.440, P=0.013). However, no correlation was seen between CCT and ST in patients with OHT, POAG, and controls. CONCLUSIONS: There is a correlation between CCT and ST among the NTG group but no correlation was seen among OHT, POAG, and controls.