The impact of prolonged low-dose radiation exposure on tear function and corneal endothelial parameters in radiation workers.

Abstract

Background: To evaluate the effects of prolonged occupational exposure to low-dose ionizing radiation (X-rays) on tear film parameters and corneal endothelial morphology among healthcare personnel, including radiology technicians and diagnostic imaging staff.

Methods: This cross-sectional study included 144 radiation-exposed participants and 91 controls. Prolonged exposure was defined as more than 10 years, with a mean annual dose of 1.7-2.1 mSv. Participants were stratified by exposure duration into three groups: <10 years, 10-20 years, and >20 years (10-year exposures were included in the 10-20-year group). Tear film was evaluated using the Ocular Surface Disease Index (OSDI), Schirmer I/II tests, tear breakup time (TBUT), tear osmolarity, and Oxford grading. Corneal endothelium was assessed via specular microscopy, including cell density (CD), coefficient of variation (CV), hexagonality (HEX), pachymetry (PACH), average cell area (AVE), and standard deviation (SD). Only one eye per participant was analyzed.

Results: Mean OSDI scores increased progressively across radiation-exposed groups (34, 52, and 67) compared to the control group (11) (P < 0.001) accompanied by a corresponding decline in Schirmer I values (15, 8, and 9 mm vs. control: 18 mm, P < 0.001). Tear osmolarity increased with chronic low-dose radiation exposure (303, 310, and 313 mOsm/L vs. control: 302 mOsm/L), and TBUT was shortened (6, 4, and 4 s vs. control: 14 s) (P < 0.001 for both). CD was reduced in radiation groups (2683, 2709, 2647 cells/mm² vs. control: 2830 cells/mm², P < 0.001), whereas CV, HEX, and PACH remained stable. Cornea guttata was more frequent in exposed individuals but did not correlate with annual dose, suggesting a potential stochastic or threshold effect.

Conclusion: Prolonged exposure to low-dose radiation is associated with early ocular surface changes and reduced endothelial CD, supporting the need for regular ocular monitoring in radiation-exposed workers.