Evaluating Key Features Influencing the Effectiveness of Ultraviolet Radiation Protection in Sunglasses

Introduction: Ultraviolet radiation (UVR) from sunlight, particularly UVA and UVB, can cause significant skin and ocular damage. While sunglasses are a critical form of protection and should meet minimum safety standards, their effectiveness varies and is not reliably indicated by brand, price, or place of purchase. Objectives To evaluate how different features of commercially available sunglasses influence their effectiveness in UVR protection. Materials and Method A total of 117 sunglasses used under real-world conditions were collected in Bangkok, Thailand. Physical characteristics and usage data were recorded. UV(A + B) and UVB transmissions were measured with Solarmeter® devices under clear-sky conditions and a high UV index (9–10). UVR protection levels were calculated and compared against international standards set by the American Academy of Ophthalmology (AAO), the Australian/New Zealand Standard (AS/NZS), and the American National Standard Institute (ANSI). Sunglasses providing less than 99% UVR protection were classified as non-compliant. Logistic regression was performed to identify factors associated with UVR protection. Results Of the 117 sunglasses tested, 87.18% met international standards for UVR protection, while 12.82% were non-compliant. Branded sunglasses were significantly more likely to provide adequate UVR protection (OR: 25.93, 95% CI: 2.87–234.38, p  = 0.004). Compliant sunglasses showed consistently high UV(A + B) and UVB protection, with both lenses averaging over 99%. In contrast, non-compliant sunglasses exhibited substantial variability, particularly in UVB protection (mean right lens: 61.01%, left lens: 62.18%). Lens width was positively associated with protection (OR: 5.63; p  = 0.045), while greater lens height was negatively associated (OR: 0.29; p  = 0.037). Other characteristics, including price, usage duration, tint color, and coating, were not significantly associated with protection levels. Conclusions Most sunglasses available in Bangkok offer adequate UVR protection, especially those with brand labels and wider lenses. However, a notable proportion of unbranded sunglasses fail to meet safety standards. Since UVR protection cannot be accurately predicted by price or appearance alone, consumers should be encouraged to choose sunglasses certified for UVR protection to ensure effective eye protection.