Choroidal Thickness In Relation To Ethnicity Measured By Enhanced Depth Imaging Optical Coherence Tomography

Objective The purpose of the study was to investigate the posterior choroidal thickness in subjects of3different ethnicities, namely Caucasians, Africans and Asians and understand whether or not a significant difference in choroidal thickness exists among these ethnic groups.Methods Data from88individuals were used in this cross-sectional, observational study. The subjects were classified into3ethnic groups:Caucasians, Africans and Asians. Study parameters included general and ophthalmic medical history taking, general physical examination, objective and subjective refraction with best corrected visual acuity determination, slit lamp examination, intraocular pressure tonometry, interferometric ocular axial length measurement, fundus photography, blood pressure manometry and fasting blood glucose level measurement. The choroid was visualized by enhanced-depth imaging spectral domain optical coherence tomography (EDI SD-OCT). The choroidal thickness was measured between calipers set on the retinal pigment epithelium\Bruch’s membrane as an anterior border and on the chorioscleral interface as a posterior border, which was detected visually and fitted manually. The data were then analyzed using the SPSS software and the results of mean subfoveal choroidal thickness were compared in relation to ethnic groups and against age, sex, refractive error and axial length. Inter-eye variability of the subfoveal choroidal thickness was analyzed as well. In order to obtain maximum precise results, the correlation between mean subfoveal choroidal thickness and ethnicity was adjusted for age, sex, axial length and spherical error.Results Males and females were perfectly matched by number in all groups;50%(44) males and so females. The mean age of the entire study population was27.43 ±1years. Ethnic and mean age distribution was as follows:34.09%,26.58±1.4years;34.09%,26.90±2years and31.81%,28.91±1.4years, Caucasians, Africans and Asians, respectively. Mean subfoveal choroidal thicknesses of Caucasians, Africans and Asians were403.62±37.4μm,372.47±31.4um and383.64±40μm, respectively. The mean subfoveal choroidal thickness of the entire study population was386.64±10.5μm. Mean spherical error distribution was-1.2685D,-1.3000D,-1.0833D,-1.4330D, entire study population, Caucasians, Africans and Asians, respectively. Caucasians had the longest eyes24.17mm>24.08mm (Africans)>23.86mm (Asians), with the statistical mean of24.04mm for the entire study population. Subfoveal choroidal thickness was not significantly correlated with ethnicity in either ethnic group (p>0.05). Subfoveal choroid thinned by2.51μm per1year increase in age, but that was not statistically significant (p=0.282). The correlation between subfoveal choroidal thickness and sex was not significant too (p=0.402). Subfoveal choroidal thickness was in strong negative correlation only with refractive error (p=0.01) and axial length (p=0.008). The difference in subfoveal choroidal thickness of right and left eyes was not statistically significant (p=0.845).Conclusion EDI SD-OCT is a productive and efficient imaging method to study the choroid and the choroidal thickness, in particular. The difference in subfoveal choroidal thickness between different ethnicities can be ignored in medical and research practice due to its insignificance. The study reproduced previously found relations between thinner choroids and longer axial lengths and increasing myopic refraction, and showed no significant associations between subfoveal choroidal thickness and age and sex. Either right or left eye can be used in future studies, since no significant difference exists.