Aim: The aim of this article is to evaluate the microstructural changes of the ocular surface in response to ultraviolet (UV) exposure, and follow their dynamics using in vivo confocal microscopy during the summer season at 430 latitude. It also aims at evaluating the UV protection habits and establishing their relationship with the results.
Methods: For a period of 4 months 50 volunteers (100 eyes), aged 25 ± 4.2 years were recruited with the agreement that they will spend their summer exclusively in the region of the Black Sea coast at 430 latitude. The participants filled out special questionnaires and underwent a comprehensive eye examination before and after the summer season, and one year after the first visit. Laser scanning in vivo confocal microscopy was performed with HRT II Rostock corneal module and 5 areas of cornea, 4 in bulbar conjunctiva, and 1 in palpebral conjunctiva of the upper eyelid of both eyes were examined.
Results: The survey results showed that 84% (42 participants) considered the sun dangerous for their eyes. However, 78% (39 participants) indicated that the danger was mainly during the summer. Microstructural analysis of the cornea showed a statistically significant reduction in basal epithelial density: from 6167 ± 151 cells/mm2 to 5829 ± 168 cells/mm2. The number of keratocytes (superficial, mid and posterior stroma) as well as endothelial cell density for the follow-up period remained numerically and statistically unchanged. Conjunctival analysis revealed characteristic cystic lesions with dark centers and bright borders found in only 6 eyes (6%) before and 30 eyes (30%) after the summer season. The total area of cysts was increased 20 times and their size also increased from 12-78 μm before, to 14-174 μm after exposure to summer sun. Statistical analysis of the data showed a negative correlation between eye sun-protection habits and microstructural damage. The analysis of the data obtained during the survey one year after the initial visit revealed a tendency to return to the baseline of all encountered features, although for some of them a complete restoration was not observed.
Conclusion: Exposure to summer sun for one season, without the use of adequate sun protection, leads to clinically undetectable, microstructural changes affecting the cornea, bulbar and palpebral conjunctiva with transient, but possibly cumulative nature. The long-term effect of these changes is probably `solar ageing of the anterior ocular surface`, which appears to be similar to the well known skin damage. The results of the survey show a need to develop a preventive program and improve public awareness of UV eye injuries.
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