The impact of anthropometric and ocular parameters on optic cup-to-disc ratio

BACKGROUND/AIMS: To assess a relationship between vertical cup-­to-­disc ratio (VCDR), which is a useful tool to assist in the diagnosis of glaucoma in the early to medium­-advanced stages, and intraocular pressure (IOP), central corneal thickness (CCT), body mass index (BMI) and body fat percentage (BFP). METHODS: The data were collected from general populations living in the centre of Japan who had participated in the third wave of the National Institute for Longevity Sciences — Longitudinal Study of Aging. VCDR was set in the general linear mixed model as objective variables with adjustment for age and optic disc area. Explanatory variables were IOP, CCT, BMI and BFP. RESULTS: 2819 eyes with no surgical history (788 men, 739 women; average age, 59.6±11.7 years) were included in the multivariate analysis. VCDR significantly increased with a low BMI in men (estimated effect=−0.0059, p=0.0426). Meanwhile, VCDR significantly increased with a high IOP (estimated effect=0.0125, p<0.0001) and a thin CCT (estimated effect=−0.4229, p=0.0425) in women. There was no significant relationship of VCDR with IOP, CCT and BFP in men and with BMI and BFP in women. Only the relationship between IOP and VCDR in women would be statistically significant after applying Bonferroni's correction for multiple comparisons, under the assumption that each analysis was not independent. CONCLUSIONS: This study demonstrated the different association with VCDR and other factors by sex. A low BMI in men and a high IOP and a thin CCT in women were indicated to be a risk factor of a greater VCDR. Meanwhile BFP was not a significant factor of a greater VCDR in both sexes.