Change of choridal thickness and its influence factors in adult high myopic patients

Abstract

Background Aheration of eyeball wall caused by ocular axial extension is associated with multiple complications of high myopia.However,the study on quantitative analysis of choroidal thickness and axial length in adult high myopic patients is less.Objective This study was to investigate the choroidal thickness in high myopic eyes of adult patients and estimate the correlation of choroidal thickness with axial length,age,and spherical equivalent(SE).Methods A prospective cohort study was designed.Seventy-five eyes of 75 adult patients with high myopia were entrolled from December 2012 to May 2013,and 70 eyes of 70 age-and gendermatched healthy volunteers were included in Renmin Hospital of Wuhan University.Enhanced depth imaging (EDI)on Cirrus spectral-domain optical coherence tomography (SD-OCT) was used to measure the choroidal thickness from the outer border of the retinal pigment epithelium through the inner scleral boarder among the 11 meridians in a 500 μm intervals and range of 2 500 μm for each from fovea toward temporal and nasal lateral.The differences of choroidal thickness and axial length were compared between the high myopia group and normal control group,and the correlation of choroidal thickness with axial length,age,SE were analyzed.Results The subfoveal and mean choroidal thickness values were (146±52) μm and (142±63) μm in the high myopia group,and those in the normal control group were (306±60) μm and (271 ±71) μm,with significant differences between the two groups (t =-17.130,P=0.000; t=-15.890,P=0.000).Choroid was thickest in the temporal and then was subfovea and nasal in the high myopia group,but in the normal control group,it was subfovea,temporal and nasal in turn,and the choroidal thicknesses in various areas were thinner in the high myopia group than those in the normal control group.A negative correlation was found between the choroidal thickness and axial length in high myopia group(r =-0.580,P =0.000),and the regression equation determined a decrease of 17.943 μm per millimeter of axial length.Conclusions SD-OCT determines that choroidal thickness is decreased in highly myopic eyes compared with normal eyes.Choroidal thickness varies with the change of axial length in adult high myopia patient.These findings indicate that abnormalities of the choroids may play a role in the pathogenesis of complication of high myopia. Key words: Choroidal thickness; Axial length; Enhanced depth imaging; Optical coherence tomography; High myopia; Adult