Early Ultraviolet-Induced Corneal Immune Changes Identified Using In Vivo Confocal Microscopy in Otherwise Healthy Eyes

Purpose: To evaluate whether incidental ultraviolet (UV) radiation exposure is associated with subclinical ocular surface inflammation and corneal immune cell changes in healthy young adults, using conjunctival UV autofluorescence (CUVAF) as a biomarker of UV exposure. Methods: Fifty-two healthy adults (18–35 years) were examined. CUVAF of the right eye was imaged and quantified. Ocular surface symptoms and signs were assessed using the ocular surface disease index, and the Efron grading scales for bulbar redness and upper tarsal conjunctival roughness. In vivo confocal microscopy was conducted to determine the density of immune cells without visible dendrites (woDCs), with dendrites (wDCs), and globular immune cells in the central and peripheral cornea. Central corneal nerve parameters were also assessed. Group comparisons were made between eyes with and without CUVAF, and correlations with CUVAF area were conducted. Results: CUVAF was present in 60% of eyes. Individuals with CUVAF demonstrated significantly greater bulbar redness and upper tarsal conjunctival roughness compared with those without. Central globular immune cell density was higher in CUVAF eyes ( P < 0.05), and both woDC and wDC densities were significantly elevated in the superior cornea ( P < 0.01). No differences were observed in central corneal nerve parameters. Conclusions: Healthy eyes displaying CUVAF exhibit measurable increases in ocular surface inflammation and corneal immune cell density, indicating subclinical inflammatory changes associated with chronic low-grade UV exposure. CUVAF may serve as a clinically accessible marker of early UV-related ocular surface injury.