Correlation between corneal and scleral thickness in glaucoma

Abstract

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 microm; POAG 519.39+/-42.95 microm; NTG 505.81+/-27.23 microm; controls 529.90+/-43.40 microm) 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 microm; POAG 738.45+/-66.83 microm; NTG 708.74+/-71.58 microm; controls 724.45+/-73.27 microm) 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.