A higher lifetime exposure to sunlight may increase the risk of developing eye freckles or dark spots on the coloured part of the eye (iris), researchers warned.
The findings showed that eye freckles could indicate the presence or risk of sunlight-triggered eye diseases like cataract or macular degeneration.
Further, the development of eye freckles also correlated with increasing age, lifetime number of sunburns and a history of severe sunburns resulting in blisters, the researchers reported.
"While we do not know the exact role of sunlight in several eye diseases, we now have a biomarker (iris freckles) indicating high amounts of chronic sunlight exposure," said Christoph Schwab, ophthalmologist at the Medical University of Graz in Austria.
In addition, people with dark coloured eyes were found less likely to have eye freckles, as well as those who maintained better sun protection habits like using sunscreen or covering up.
For the study, published in the journal Investigative Ophthalmology & Visual Science, over 600 swimmers at public pools in Styria, Austria, had their eyes examined for freckles and filled out a questionnaire that asked about their lifetime sun exposure and sun-protection habits.
Researchers also found that freckles were most commonly found in the lower outer quadrant (away from the nose) of each eye.
This may be because the eyebrow and nose shield the upper and inner quadrants of the eye from the sun, lowering exposure and the risk of developing freckles, Schwab explained.