The relationship between central corneal thickness and intraocular pressure: a comparative study of normals and glaucoma subjects.

The purpose of the study is to determine whether central corneal thickness (CCT) is a better predictor than intraocular pressure (IOP) in early identification of those at higher risk of developing glaucoma. Sixty-five subjects were categorized into normals, ocular hypertensives and glaucoma subjects based on clinical characteristics of ocular risk factors. The lOP was assessed with slit-lamp mounted Goldmann applanation tonometer. Prior to applanation tonometry, the central corneal thickness (CCT) of both eyes was assessed with Sonomed PacScan 300AP Biometric/pachymeter. The difference in mean IOP between normals and glaucoma subjects was statistically significant (unpaired t-test; p<0.05). Similarly, there was a significant difference in mean CCT between normals and glaucoma subjects (p<0.05). The association between CCT and Age was not significant in normals but slightly significant in glaucoma subjects and the linear regression predicts a decrease of 7.0 ìm in CCT for every 10 years. A strong association was found between CCT and IOP for ocular hypertensives with a prediction of increase of 0.70 mmHg for every 10 ìm corneal thickening. The association between CCT and IOP for glaucoma subjects was weak, with an indication of an increase of 0.35 mmHg in intraocular pressure for every 10 ìm corneal thinning. The central corneal thickness is a better predictor than intraocular pressure in identifying those at higher risk of developing primary open-angle glaucoma when combined with some ocular risk factors.