A Study of Central Corneal Thickness in Glaucoma and Nonglaucoma Patients in a West African Population

Purpose: To compare central corneal thickness (CCT) in high-tension glaucomatous eyes and nonglaucomatous eyes with normal intraocular pressure (IOP) and to determine if there is any correlation between CCT and severity of glaucoma, as indicated by vertical cup-to-disc ratio. Methods: A case-control study that involved 506 subjects at the Korle-Bu Teaching Hospital, Accra, Ghana, from August 2006 to July 2007. The cases were patients with (high tension and IOP more than 21 mm Hg) primary open-angle glaucoma, and the controls were patients with normal IOP (less than 21 mm Hg) and no evidence of glaucoma. The main outcome measures were CCT, as measured by ultrasonic pachymetry (model DGH 55 pachmate), and vertical cup-to-disc ratio. Results: Five hundred six subjects were recruited: 253 cases (506 eyes) and 253 controls (505 eyes). The mean CCT of the right eye for the glaucoma cases was 524.28 mu m [95% confidence interval (CI), 4.44; SD, 36.85] and for the controls was 530.00 mu m (95% CI, 4.56; SD, 35.75). The mean CCT of the left eye for the glaucoma cases was 524.70 mu m (95% CI, 4.48; SD, 36.20) and for the controls was 531.06 mu m (95% CI, 4.40; SD, 35.52). The relation between CCT and cupping determined by Pearson correlation coefficient yielded values of -0.09 and 0.01 for the right and left eyes, respectively. Conclusion: There was no significant difference between mean CCT of cases and controls in the right eye (P = 0.08), but there was a weakly significant difference in the CCT of the left eye (P = 0.05). Also, there was no correlation between cup-to-disc ratio and CCT.