Distribution characteristics of corneal thickness in healthy children aged 7-15 years in Baoshan District of Shanghai

Abstract

Background Measurement of corneal thickness is important for the early diagnosis and treatment of some eye disorders,including corneal diseases and refractive errors.However,the corneal parameters from schoolage population are rarely reported.Objective The aim of this survey was to characterize the central corneal thickness (CCT),minimum corneal thickness (MCT) and paracentral corneal thickness in healthy Chinese schoolage population.Methods A cross-sectional study was designed in this study.Children aged 7 to 15 years with the diopter of-3.00 D to +3.00 D were recruited from two primary schools in Baoshan district in Shanghai based on random cluster sampling under the approval of Shanghai First People's Hospital and informed consent of child custodian.Routine examinations were firstly performed to determine the healthy participants.CCT (within 2 mm range away the corneal vertex),MCT and paracentral corneal thicknesses (2 to 5 mm zone away the cornea vertex in superior,inferior,nasal and temporal quadrants) were then measured by RTVue Fourier optical coherence tomography (OCT) for the comparison between both eyes and different gender.The subjects were grouped into the 7-9,10-12 and 13-15 years groups,and the correlations between age and CCT,MCT and paracental corneal thicknesses were analyzed.The coordinate position of the thinnest cornea was determined.Results A total of 147 children were enrolled in the study.The mean CCT value of the right eyes was (537.77±29.33) μm,and that of the left eyes was (539.22±29.16) μm,showing a significant difference between them (t =-3.21,P =0.00).The paracentral corneal thicknesses of the right and left eyes were (565.52±30.11) μm and (568.42±31.07) pm in the superior quadrant,and those in the temporal quadrant were (549.01 ±30.46) μm and (547.24±30.23) μm,with significant differences between them (t =-2.47,P =0.01 ; t =2.12,P =0.04).No significant difference was found in the CCT,MCT,paracentral corneal thicknesses from various quadrants (all at P＞0.05).In addition,no considerably correlation was seen between age and CCT,MCT and paracentral corneal thickness (all at P＞0.05).The thinnest cornea area was located in the inferotemporal region in 40.82％ right eyes and 57.82％ left eyes.The distance of thinnest cornea area away corneal vertex was (0.62±0.33)mm in the right eyes and (0.91±0.63)mm in the left eyes,with a significant difference between them (t =-5.17,P =0.00).Conclusions The central,superior and temporal corneal thicknesses are significantly different between the right and the left eyes among healthy Chinese school-age children,but corneal thickness change is not associated with age or gender.The thinnest corneal area does not locate at the vertex. Key words: Biometrics; Corneal thickness; Optical coherence tomography; Child; Healthy