Corneal Epithelial Cell Density Is Reduced in Young Adults With Conjunctival Ultraviolet Autofluorescence

Purpose: The aim of this study was to investigate the effects of chronic ultraviolet (UV) radiation exposure on the corneal microstructure using conjunctival UV autofluorescence (CUVAF) as a marker of exposure. Methods: Young healthy adults aged 18 to 35 years were recruited. Participant's demographics and sun exposure behavior were recorded using questionnaires. Images of the bulbar conjunctiva from the right eye were captured and analyzed for the CUVAF area. Corneal microstructure was assessed by in vivo confocal microscopy and anterior segment optical coherence tomography. The presence of palisades of Vogt in all 4 limbal quadrants was recorded. Results: CUVAF was observed in 31 of 52 eyes (60%), with a mean (SD) nasal, temporal, and total CUVAF area of 5.39 +/- 4.16 mm(2), 4.29 +/- 4.27 mm(2), and 9.67 +/- 7.01 mm(2), respectively. Individuals with CUVAF were significantly more likely to report undertaking moderate-intensity to high-intensity outdoor exercise (P = 0.021). Individuals with CUVAF were less likely to have visible nasal and temporal palisades of Vogt (P = 0.011). Corneal basal cell densities anterior to the nerve whorl (P < 0.001) and nasally (P = 0.005) were lower in individuals with CUVAF. Wing cell density anterior to the nerve whorl was lower in individuals with CUVAF (P = 0.011). No significant changes in the central and limbal corneal epithelial thickness were observed. Conclusions: Significant reductions in corneal epithelial cell density were observed in individuals with CUVAF, a biomarker of chronic UV exposure. This observation suggests that chronic UV exposure is damaging to the corneal microstructure.