The Association of Central Corneal Thickness with Ocular and General Parameters in a Community Setting: The Yazd Eye Study

PURPOSE To assess central corneal thickness (CCT) and its associations in an adult Iranian population. METHODS This was a population-based cross-sectional study of adults aged 40-80 years. Eyes with corneal disorders, previous ocular surgery, or trauma were excluded. All subjects underwent complete ophthalmic examination, general health assessment, laboratory tests, and a detailed interview. CCT was measured with an ultrasonic pachymeter. Intraocular pressure (IOP) was measured with Goldmann applanation tonometry. Except for the report on interocular differences in CCT, only one eye of each subject was used for the rest of statistical analyses. RESULTS The mean age (±SD) of the 1203 participants, who had CCT measurements and met inclusion criteria, was 51.8 ± 8.5 years. The mean CCT was 544 ± 35, 564 ± 28, and 544 ± 36 μm in the eyes of the normal, ocular hypertension, and glaucoma groups, respectively (P = 0.025). In participants without glaucoma, the mean interocular difference in CCT was 9 ± 12 μm. CCT was not significantly associated with age, sex, or some select systemic factors (body mass index, diabetes, hypertension, and renal failure). While controlling for age and sex, CCT was greater in individuals with higher IOPs (P < 0.001), larger vertical or horizontal cup-to-disc ratios (P = 0.044, and P = 0.025, respectively), and hyperopia (P = 0.009). CONCLUSION In this adult Iranian population, CCT was significantly associated with IOP, cup-to-disc ratio, and the refractive status of eye. CCT outside the normal range of 475-613 μm or with interocular asymmetry greater than 33 μm (6%) should prompt evaluation for potential ocular disorders.