CPT code 83861 designates microfluidic analysis of tear osmolarity, a laboratory diagnostic test used in the assessment of patients with symptoms of dry eye. Nationally, this code matters because tear osmolarity is a quantitative biomarker increasingly used to inform clinical evaluation of ocular surface disease and to support care decisions in ophthalmology and optometry settings. The test is typically performed in outpatient eye clinics, specialty eye care centers, or clinical laboratories and is billed when a lab analyst conducts the microfluidic assay.

Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of clinical context for the test, typical sites of service, and payer coverage considerations. The publication highlights common billing modifiers and operational notes and identifies where input data is not available, such as associated taxonomies, specific ICD-10 pairings, or related codes. This summary equips revenue, compliance, and clinical teams with concise background and the topics to expect in the full publication, including benchmarks, payer policy variations, and clinical use cases for tear osmolarity testing.