Macular thicknesses and their associations with ocular and demographic variables in black South Africans

Abstract

Purpose: To determine normal macular thicknesses and their associations with demographic and ocular variables in healthy eyes of black South Africans. Methods: Six hundred healthy subjects (N = 600) underwent height and weight measurements followed by a complete ophthalmic examination, which included auto-refraction, subjective refraction, slit-lamp biomicroscopy, ocular biometric measurements and tonometry. Intraocular pressure (IOP) was measured with the Nidek NT530P (Tonopachy™) and the axial length (AL) thickness with the Nidek Echoscan. The central corneal thickness (CCT) and macular thickness were measured using iVue-100 spectral-domain optical coherence tomography (Optovue, Inc.). The macular thickness map protocol that divides the macular area into nine regions of the Early Treatment Diabetic Retinopathy Study (ETDRS) fields was used. Variations in macular thickness measurements with body mass index (BMI), age, gender, refraction, AL, CCT and IOP were determined with partial correlation analysis. Results: The 600 subjects had a mean age of 28.15 ± 13.09 years (range = 10-66 years), with 305 (50.83%) being males and 295 (49.17%) females. The thickness values of the central, inner and outer maculae were normally distributed, with means of 235.89 μm ± 20.04 μm, 303.56 μm ± 18.68 μm and 287.81 μm ± 14.61 μm, respectively. Mean total macular thickness for all subjects was 268.72 ± 15.04 μm. The temporal quadrant was markedly thinner than all other quadrants for both inner and outer macular regions. Macular thicknesses were greater in men than in women (p < 0.05). The thickness of mean central, mean inner and mean outer maculae increased significantly with increasing BMI (p < 0.001). Central, inner and outer maculae were significantly associated (p < 0.001) with a high hyperopic spherical equivalent refraction. AL was associated with a thin inner macula (p < 0.05) and an outer macula (p < 0.001), but not with a thinner central macula (p > 0.05). Age, CCT and IOP were not associated with macular thickness values in any quadrant (p > 0.05). Conclusion: The macular values were thinner in women than in men and were related to BMI, gender, hyperopic spherical refraction and AL with regional variations. These differences should be considered when interpreting optical coherence tomography results for accurately diagnosing and managing retinal abnormalities.