Evaluation of Sunglasses’ Performance to Filter Harmful Short Wavelength Lights

Background and aims: Sunlight contains a wide range of lights with different wavelengths, and some parts of it, especially short-wavelength spectra, can damage different parts of the eye and cause or exacerbate diseases such as cataracts. The aim of this study was to evaluate the effectiveness of sunglasses in filtering harmful light with short wavelengths. Methods:Inthiscross-sectionalstudy,56pairs(112lenses)ofbrandedsunglasses were collected from different importing companies. A spectrophotometer (Reflectance Spectrophotometer, Cecil instrument, UK) was used to measure the UV and blue light transmissions. For statistical analysis, non-parametric Mann-Whitney and Kruskal-Wallis tests were used. A P ≤ 0.05 was considered statistically significant. Results: The mean UVA and UVB transmission of the sunglasses were 0.16±1.21% and 0.01±0.06 %, respectively. The mean blue light transmission of the sunglasses was 10.03 ± 3.91 %. The effect of different colors on the blue light transmission was significant (P≤0.001). Polarization and visible light transmission of the sunglasses had no significant effect on the blue light transmission (P=0.3). Conclusion: The effectiveness of available sunglasses to filter hazardous lights was acceptable, among them brown colored sunglasses was the best option to filter blue light.