Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 56 5 2018 05 20 320 328 EN Hassan Hashemi Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran. Abbasali Yekta Refractive Errors Research Center, Mashhad University of Medical Sciences, Mashhad, Iran. Mohammad Saatchi Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran. Raheleh Moravej Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran. Mohamadreza Aghamirsalim Eye Research Center, Rassoul-e-Akram Hospital, Iran University of Medical Sciences, Tehran, Iran. Mehdi Khabazkhoob Department of Medical Surgical Nursing, School of Nursing and Midwifery, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 2017 09 02 2017 12 19 To determine the distribution of corneal thickness and its associated factors in the over 5-year-old population in the north and south rural areas in Iran. In this study, samples were selected using multi-stage cluster sampling. After vision and refraction tests and the slit lamp exam, the central corneal thickness (CCT), apical corneal thickness (ACT), and the thickness at four peripheral areas of the cornea were measured using Pentacam. Of the 3851 selected samples, after applying the exclusion criteria, the analysis was done on data from 2681 people. The mean age of the participants was 36.03±18.51 years, ranging from 6 to 90 years, and 58.1% of them were female. Mean CCT and ACT were 533.87 μm (95%CI: 532.05 -535.69) and 536.72 μm (95%CI: 534.9 -538.54), respectively. Mean peripheral corneal thickness was 637.46 μm (95%CI: 635.09 -639.83) in the superior quadrant, and 594.34 μm (95%CI: 592.2 -596.47), 620.81 μm (95%CI: 618.66 -622.97), and 584.55 μm (95%CI: 582.18 -586.93) in the inferior, nasal, and temporal quadrants, respectively. Linear regression analysis showed significant associations between CCT and gender (P=0.001), age (P<0.001), geographical location of residence (P<0.001), the radius of corneal curvature (P<0.001), anterior chamber depth (P<0.001), and corneal volume (P<0.001). This study is one of the few studies describing the distribution of the corneal thickness in a population of over 5-year-olds using Pentacam. Gender, anterior chamber depth, and corneal radius of curvature are some of the factors associated with CCT. https://acta.tums.ac.ir/index.php/acta/article/view/6676 https://acta.tums.ac.ir/index.php/acta/article/download/6676/5091