Central Corneal Thickness and Its Association with Ocular and General Parameters in Indians: The Central India Eye and Medical Study

Purpose: To evaluate the distribution of central corneal thickness (CCT) and its associations in an adult Indian population. Design: Population-based study. Participants: The Central India Eye and Medical Study is a population-based study performed in a rural region close to Nagpur in Central India; it included 4711 subjects (ages 30+ years) of 5885 eligible subjects (response rate, 80.1%). Methods: The participants underwent a detailed ophthalmic and medical examination, including 200 standardized questions on socioeconomic background, lifestyle, social relations, and psychiatric depression. This study was focused on CCT as measured by sonography and its associations. Intraocular pressure was measured by applanation tonometry. Main Outcome Measures: Central corneal thickness and intraocular pressure. Results: Central corneal thickness measurement data were available on 9370 (99.4%) eyes. Mean CCT was 514 +/- 33 mu m (median, 517 mu m; range, 290-696 mu m). By multiple regression analysis, CCT was associated significantly with younger age (P<0.001), male gender (P<0.001), higher body mass index (P = 0.006), lower corneal refractive power (P<0.001), deeper anterior chamber (P = 0.02), thicker lens (P = 0.02), and shorter axial length (P = 0.006). Central corneal thickness was not associated significantly with refractive error (P = 0.54) or cylindrical refractive error (P = 0.20). If eyes with a corneal refractive power of 45 or more diopters were excluded, the relationship between CCT and axial length was no longer statistically significant (P>0.05), whereas all other relationships remained significant. Intraocular pressure readings increased significantly (P<0.001) with both higher CCT and higher corneal refractive power. Conclusions: Indians from rural Central India have markedly thinner corneas than do Caucasians or Chinese, and, as in other populations, CCT is greater in men. CCT was associated with younger age, higher body mass index, lower corneal refractive power, deeper anterior chamber, thicker lens, and shorter axial length. Intraocular pressure readings were associated with CCT, with high readings in those eyes that had thick corneas or steep corneas. Central corneal thickness and steepness of the anterior corneal surface may thus both have to be taken into account when applanation tonometry is performed. Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article. Ophthalmology 2010;117:705-710 (C) 2010 by the American Academy of Ophthalmology.