Healthcare costs due to diplopia in Korea: analyses using the public data of Health Insurance Review and Assessment Service.

Diplopia is a disabling condition with diverse etiologies, but population-based studies on its healthcare utilization and healthcare costs are limited in South Korea. We conducted a nationwide cross-sectional study using all claims data submitted to the Korean Health Insurance Review and Assessment Service in 2023. Patients with diplopia were identified using diagnostic codes for diplopia and strabismus. Direct healthcare costs, healthcare utilization patterns, and demographic characteristics were analyzed, with subgroup analyses for ocular motor cranial nerve palsies. Among 51.4 million insured individuals in South Korea, 89,447 patients with diplopia were identified, corresponding to a one-year prevalence of 0.17%. Age-specific prevalence revealed a bimodal age distribution. A total of 248,431 diplopia-related healthcare visits were recorded, primarily managed in ophthalmology (70.2%) and neurology (21.3%). The annual direct healthcare cost attributable to diplopia was ₩59.9 billion, and the mean cost per visit or admission day was ₩241,077, approximately 3.1 times the national average insurance benefit cost per outpatient visit or inpatient day (₩76,553). This nationwide claims-based study demonstrates that diplopia is associated with substantially higher healthcare costs than the national average across all medical conditions, with marked heterogeneity by age and underlying etiology. These findings underscore the need for age- and etiology-based, multidisciplinary strategies for optimized care and reducing healthcare costs of diplopia.