43 A new large-scale study has provided fresh insights into the potential links between ambient ultraviolet radiation (UVR) and ocular melanoma, a rare but potentially deadly cancer of the eye. The study, which spanned from 2000 to 2019, analysed data from over 18,000 cases of ocular melanoma in the US, revealing both positive and negative associations between UVR exposure and specific types of eye melanoma. The findings were published in the journal Eye. Ocular melanoma accounts for approximately 2,000 new cases in the US each year and can lead to significant complications, including vision loss and death, particularly when the cancer spreads. Despite its rarity, the disease’s aggressive nature underscores the importance of identifying risk factors to help with prevention and early detection efforts. The study, led by researchers from the National Cancer Institute and other academic institutions, used data from 21 cancer registries. The research aimed to explore whether solar UVR played a role in the development of ocular melanoma, an area where previous studies have provided inconsistent findings. In particular, the study examined how UVR exposure affects different anatomical sites of the eye, such as the choroid, iris, and conjunctiva. One of the key findings was that exposure to UVR was not strongly linked to an increased overall risk of ocular melanoma. In fact, the study found no significant association between UVR and total ocular melanoma or conjunctival melanoma. However, when specific areas of the eye were considered separately, the results told a different story. For instance, the study identified an increased risk of ciliary body and iris melanoma, especially in non-Hispanic White individuals, in regions with higher UVR exposure. Interestingly, the study also uncovered a reduced risk of choroidal melanoma, the most common type of ocular melanoma, in areas with higher UVR exposure. The researchers theorised that this might be due to the protective positioning of the choroid, located in the posterior section of the eye, which may receive less UVR. In contrast, the iris, which is at the front of the eye, is more directly exposed to sunlight, which could explain the increased melanoma risk in this region. The findings suggest that UVR’s impact on eye cancer risk may vary depending on the specific part of the eye affected. These nuanced results contribute to a more comprehensive understanding of how environmental factors like UVR influence the development of ocular melanoma. For years, there has been ongoing debate in the scientific community about whether solar UVR contributes to the development of ocular melanoma. While artificial UVR, such as from tanning beds, has been linked to an increased risk, the connection to natural sunlight has remained unclear. The new study’s results provide further evidence that while UVR may not significantly increase the overall risk of ocular melanoma, it may still play a role in the development of certain types of the disease. The study’s findings could have implications for public health strategies aimed at preventing ocular melanoma, particularly in regions with high UVR levels. However, the researchers caution that more work is needed to fully understand the relationship between UVR and ocular melanoma, including the potential role of other risk factors such as age, skin pigmentation, and genetic predisposition.