Skin Melanin Content and the Foveal Avascular Zone Correlation in a Healthy White Population

This study aimed to investigate the correlation between skin melanin content and foveal avascular zone (FAZ) characteristics in healthy White subjects and to determine whether melanin expression influences foveal morphology.

In this cross-sectional study, 154 eyes from healthy volunteers 18 to 55 years old underwent comprehensive ophthalmic examinations including optical coherence tomography angiography (OCTA) imaging. The FAZ area was manually delineated from OCTA images. Skin melanin content was measured using a colorimeter at three anatomical sites to obtain a melanin index. Pearson's correlation and multivariable linear regression analyses were performed to assess associations among the melanin index, FAZ area, axial length (AL), central foveal thickness (CFT), and the presence of persistent foveal inner retinal layers.

A statistically significant positive correlation was observed between the melanin index and FAZ area (r = 0.394, P < 0.001). Multivariable analysis revealed that each 100-unit increase in the melanin index was associated with a 0.12-mm2 increase in FAZ area (P < 0.001), whereas age, sex, and AL were not found to be associated with FAZ. Furthermore, a lower melanin index was significantly associated with the likelihood of foveal inner retinal layer persistence (odds ratio = 0.98) and higher CFT (β = -0.11, P = 0.02).

These findings suggest that physiological variations in cutaneous melanin may be associated with FAZ dimensions and foveal architecture in healthy White individuals. Melanin-related pathways appear to play a regulatory role in retinal development, highlighting the need to consider pigmentation when using FAZ measurements as biomarkers in ocular and systemic diseases.