The Distribution of Macular Thickness and Its Determinants in a Healthy Population

Abstract

© 2017 Taylor & Francis Purpose: To determine the distribution of macular thickness in a healthy Iranian population aged 45–69 years and its association with certain determinants. Methods: All participants underwent optometric examinations including measurement of uncorrected and corrected visual acuity, objective refraction by retinoscopy, and subjective refraction. Subsequently, all participants underwent slit-lamp biomicroscopy followed by fundus examination through direct and indirect ophthalmoscopy, and optical coherence tomography (OCT) imaging under pupil dilation. Results: Mean central macular thickness was 255.4 µm (95% confidence interval, CI, 254.5–256.3 µm), average inner macular thickness was 316.5 µm (95% CI 315.9–317.1 µm), average outer macular thickness was 275.3 µm (95% CI 274.8–275.8 µm), and overall average thickness was 278.6 µm (95% CI 278.1–279.1 µm). A linear multiple regression model showed that all indexes were significantly larger in male participants (p < 0.001). Central macular thickness increased with age (coef = 0.25, p < 0.001) while overall, inner and outer macular thickness decreased with age (coef = −0.18, −0.15, −0.19, respectively, all p < 0.001). Central and inner macular thickness had a positive correlation (coef = 3.8, 2.6, respectively, both p < 0.001) and outer macular thickness had a negative correlation (coef = −1.6, p < 0.001) with axial length. Conclusion: Age, sex, refractive error, axial length, and keratometry were found to be associated with macular thickness. These factors should be taken into account when interpreting macular thickness measurements with spectral-domain OCT.