Associations of Metabolically Healthy Obesity and Retinal Age Gap

We investigated the association between metabolically healthy obesity (MHO) and retinal age gap and explored potential sex differences in this association.

This study included 30,335 participants from the UK Biobank. Body mass index (BMI) was classified into normal weight, overweight, and obesity. Metabolic health (MH) was defined as meeting the following criteria: systolic blood pressure of <130 mm Hg, no antihypertensive drugs, waist-to-hip ratio of <0.95 for women or 1.03 for men, and the absence of diabetes. Participants were categorized as MH normal weight (MHN), MH overweight (MHOW), MHO, metabolically unhealthy normal weight, metabolically unhealthy (MU) overweight, and MU obesity. Retinal age gap was defined as the difference between retinal age and chronological age. Linear regression models were used to investigate the association of metabolic phenotypes of obesity with retinal age gap.

Compared with MHN, individuals with MHOW (β, 0.17; 95% confidence interval [CI], 0.01-0.32; P = 0.039) and MHO (β, 0.23; 95% CI, 0.02-0.44; P = 0.031) were associated with increased retinal age gap. Furthermore, individuals classified as metabolic unhealthy were also associated with higher retinal age gap, irrespective of body mass index categories (β for MU normal weight, 0.23; 95% CI, 0.08-0.38; P = 0.003; β for MU overweight: 0.31; 95% CI, 0.18-0.45; P < 0.001; β for MU obesity, 0.50; 95% CI, 0.36-0.65; P < 0.001). No significant sex difference was observed in the association between metabolic phenotypes of obesity and retinal age gap (all P for interaction > 0.05).

MHOW and MHO were associated significantly with an increased retinal age gap compared with MHN individuals. Weight management should be recommended for individuals who are overweight or obese, even in the absence of metabolic unhealth.

Retinal age gap provides a simple tool for identifying early health risks for MHOW and MHO individuals.