Relationship between visual acuity and muscle mass in the Korean older population: a cross-sectional study using Korean National Health and Nutrition Examination Survey

Objectives We aimed to assess the effects of visual acuity on muscle mass, which is an important indicator of health in older populations. Design Pooled-sample cross-sectional study. Setting Nationally representative population survey data. Participants The present study analysed men aged 65 years or older who participated in the Korea National Health and Nutrition Examination Survey (KNHANES, 2008-2011). Primary and secondary outcome measures Muscle mass was measured by dual-energy X-ray absorptiometry scan, and low muscle mass was defined as appendicular skeletal mass divided by height squared (kg/m(2)) <6.43 kg/m(2) (lowest quintile of the older population in KNHANES, 2008-2011). Visual acuity was evaluated based on best-corrected visual acuity of the better eye. Results Of the 1733 participants, 89.9% had good visual acuity. After adjusting for age, the height-adjusted appendicular skeletal muscle mass values were 7.16 and 7.00 kg/m(2) in the good and poor vision groups, respectively (p=0.042). According to our criterion for low muscle mass, the prevalence of low muscle mass was 16.4% and 34.7% in the good and poor vision groups, respectively. After adjusting for age, smoking status, alcohol consumption status, frequency of physical activity, educational level, the status of basic livelihood recipient and history of stroke, the poor visual acuity group had higher odds of low muscle mass than the good visual acuity group (OR=1.60; 95% CI 1.02 to 2.50; p=0.040). Conclusions Older men with decreased visual acuity have low muscle mass. Poor vision might be an indicator of low muscle mass.