Heritability of macular thickness determined by optical coherence tomography

To examine whether genetic factors significantly influence macular thickness in healthy older subjects.

A classic twin study was performed to compare the correlation of macular thickness between monozygotic (MZ) and dizygotic (DZ) twins in a sample of population-based volunteer twins. The study included 109 white twin pairs from 50 to 80 years of age without evidence of manifest eye disease and corrected visual acuity better than 6/7.5. Dilated macular optical coherence tomography (OCT), fundus photography, clinical examination, ocular biometry, a health-dietary questionnaire, and subjective autorefraction were performed on all subjects.

Correlation of retinal thickness was significantly greater between MZ twin pairs than DZ pairs in all macular regions. The MZ-to-DZ correlation was 0.88:0.44 for the foveal region, 0.79:0.47 for the inner macular region, and 0.81:0.50 for the outer macular region. With adjustment for significant covariates and model fitting, final heritability estimates of 85%, 81%, and 81%, respectively, were obtained. A significant correlation between foveal thickness and gender was present, with the men having significantly thicker foveae. There was a significant negative correlation between outer macular thickness and axial length.

This study confirms that macular thickness in older healthy subjects, as measured by OCT, may be affected by genetic factors. Factors such as axial length, gender and age, warrant further examination in larger population-based studies, as variables that may influence macular thickness. This finding suggests an inherited basis of macular thickness and may help in the understanding of the factors that govern macular structure and function.