The relationship between central corneal thickness and the optic disc in an elderly population: the Bridlington Eye Assessment Project

PURPOSE: To determine population-based normative CCT data for elderly white subjects, with and without diabetes, and to explore the relationship between CCT and IOP and HRT2 measurements in such subjects with normal visual fields.

METHODS: All eligible subjects were consecutive in a population screened for eye disease. CCT was measured by ultrasound pachymetry, and the optic disc was morphometrically defined using Heidelberg retinal tomography (HRT2). Inclusion criteria were: (1) normal visual field on suprathreshold testing and (2) corrected logMAR acuity of at least 0.3 in both eyes. Subjects with significant corneal pathology, previous corneal surgery, or known history of glaucoma or treatment for raised intraocular pressure were excluded. One eye was randomly selected from each subject for analysis.

RESULTS: In all, 983 eyes of 983 subjects were included with 690 HRT images deemed acceptable for the analysis. The mean age (414 men and 569 women) was 73.3 years (minimum 65 years). Mean (SD) CCT was 544.1 (36.5) microm, with a normally distributed range of 429-633 microm. There was no significant difference in CCT between men and women (mean CCT 546.1 and 542.7 microm, respectively, P=0.15, Student's t-test), though CCT was correlated weakly and negatively with age (Pearson's r=-0.063, P=0.047). Diabetic patients (n=103) had a greater mean CCT than non-diabetic patients (551.9 and 543.0 microm respectively, P=0.02). No significant correlation was found between any global optic disc parameter and CCT in the 690 eyes analysed.

CONCLUSION: Elderly white eyes with normal fields have CCTs that are normally distributed, with those from diabetic persons having greater CCTs. No clear evidence of a relationship between CCT and HRT2 optic disc parameters used in glaucoma diagnosis was found.