Analysis of relationship between subfoveal choroidal thickness and refraction

Abstract

Background Choroidal thickness is closely associated with ametropia,and to study the influence of subfoveal choroidal thickness (SFCT) on refraction is very important for understanding the mechanism of refractive error more clearly.Objective This study was to investigate the relationship between SFCT and refraction.Methods A retrospective serial cases analysis was performed.Forty anisometrope patients were recruited in Zhongshan Ophthalmic Center from June 2012 to August 2012.The subjects were divided into 6-13 years group and 14-21 years group.Vision acuity was tested by the EDTRS visual acuity chart and ocular anterior segment was examined under the slit lamp microscope,and the fundus examination was performed by direct ophthalmoscope.Subjective and objective optometry was performed after pupils were dilated.EDI OCT was used to illuminate choroidal image.Ocular axial length (AL) was obtained by Lenstar 900.The difference in SFCT between myopic eyes and hyperopic eyes was compared using Student t test,and the correlations between SFCT and refraction were analyzed by Pearson linear analysis and linear regression analysis.Results The average SFCT was (307.82±88.47) μm in all the tested eyes,and the SFCT of myopic eyes and hyperopic eyes was (270.60±70.57) μm and (376.95±76.59) μm,respectively,with a significant difference between them (P =0.000).In the 6-13 years group,positive correlations were found between SFCT and diopters with the regression coefficient 18.60 and regression equation Y =18.60X +310.79 (r=0.345,F=21.110,P=0.000) as well as between SFCT and AL with the regression coefficient -31.76 and regression equation Y =-31.76X+1 039.97 (r=0.262,F=17.320,P=0.000).In the 14-21 years group,SFCT showed positive correlation with diopters,with the regression coefficient 23.38 and regression equation Y=23.38X+353.17 (r =0.430,F =27.210,P =0.000) and negative correlation with AL,with the regression coefficient-35.82 and regression equation Y =-35.82X+1 132.75 (r=0.237,F=15.650,P=0.000).Conclusions SFCT seems to be positive correlated with diopter.When the diopter shifts toward positive value,SFCT value increases,and whenever diopter increases-1 D,SFCT decreases 20 μm approximately.SFCT decreases with the increase of AL. Key words: Tomography; Optical coherence tomography; Biomeasurement; Subfoveal choroidal thickness; Ametropia, myopia, hyperopia