Background: The purpose of this prospective case-control study was to investigatewhether exposure to ultraviolet (UV) light produces detectable damage to the corneal endothelium in patientspresenting with acute UV keratitis. Material/Methods: Non-contact specular microscopy was performed on20 consecutive patients who presented to our clinic from July 2000 to July 2002 with acute UV keratitisand similarly on 20 age-matched healthy controls. Both the coefficient of variation in mean cell size(CV) and the mean cell density (CD) were compared in these two groups using the Student t-test. Results:Mean age was 28.6 years in the study group and 28.4 years in the control group. The mean CD in the patientgroup was 2609.6 (SD=103.47) and in the control group 2632.87 (SD=117.05). No statistically significantdifference was found between the mean CDs in these two groups (p=0.93). The mean CV in the patient groupwas 46.7 (SD=4.40) and in the control group 45.4 (SD=5.60). Similarly, there was no statistically significantdifference between the mean CVs in these two groups (p=0.85). Conclusions: UV light exposure does notseem to have a direct immediate effect on the corneal endothelium in humans with acute UV keratitis.Whether UV light produces cumulative and/or longer-term damage requires further studies with a largernumber of patients and a longer follow-up time.

Keywords: Case-Control Studies, Endothelium, Corneal - radiation effects, Keratitis - pathology, Occupational Diseases - pathology, Prospective Studies, Radiation Injuries - pathology, Ultraviolet Rays - adverse effects, Welding