Relationship between fundus sex index obtained using color fundus parameters and body height or axial length in the Kumejima population.

Purpose: To investigate the relationship between the fundus sex index obtained from fundus photographs and body height or axial length in the Kumejima population.

Study design: Prospective cross-sectional observational population study.

Methods: Using color fundus photographs obtained from the Kumejima population, 1,653 healthy right eyes with reliable fundus parameter measurements were included in this study. The tessellation fundus index was calculated as R/(R + G + B) using the mean value of the red-green-blue intensity in the eight locations around the optic disc and foveal region. The optic disc ovality ratio, papillomacular angle, and retinal vessel angle were quantified as previously described. The masculine or feminine fundus was quantified using machine learning (L2 regularized binominal logistic regression and leave one out cross validation), with the range of 0-1 as the predictive value, and defined as the fundus sex index. The relationship between the fundus sex index and body height or axial length was investigated using Spearman's correlation.

Results: The mean age of the 838 men and 815 women included in this study was 52.8 and 54.0 years, respectively. The correlation coefficient between fundus sex index and body height was - 0.40 (p < 0.001) in all, 0.01 (p = 0.89) in men, and - 0.04 (p = 0.30) in women, and that between fundus sex index and axial length was - 0.23 (p < 0.001) in all, - 0.12 (p < 0.001) in men, and - 0.13 (p < 0.001) in women.

Conclusion: This study shows that a larger number of masculine fundi tend to have longer axial lengths in each sex group. However, sex index was not significantly related with body height either in men or in women.