Measurements of transmission spectrums and estimation of retinal blue-light irradiance values of currently available clear and yellow-tinted intraocular lenses

Abstract

To compare the spectral transmission characteristics of currently available, foldable, clear and yellow-tinted intraocular lenses (IOLs), and evaluate the protective effects they provide against retinal damage by sunlight. We measured the spectral transmittance in the wavelength range of 300-800 nm using a spectrophotometer for 63 IOLs including three clear IOLs (N4-18B, Nidek; X-60, Santen; KS-3Ai, Staar Japan) and four yellow-tinted IOLs (N4-18YG, Nidek; NX-60, Santen; KS-AiN, Staar Japan; NM-1, Hoya) with three different lens powers. The blue-light irradiance (BLI) values through the IOLs were calculated as the retinal hazard index for sungazing. The data from three clear IOLs (SA60AT, Alcon Japan; VA-60BBR, Hoya; AU6K, Kowa) and three yellow-tinted IOLs (SN60AT, Alcon Japan; YA-60BBR, Hoya; AU6N, Kowa) reported previously were also discussed. Except for the X-60, the clear IOLs completely absorbed ultraviolet (UV) light and nearly completely transmitted visible light at wavelengths longer than 440 nm. Yellow-tinted IOLs absorbed more in the blue-light range (400-500 nm) than clear IOLs. All IOLs had lower BLI values than aphakic eyes, and all yellow-tinted IOLs had lower BLI values than phakic eyes. The BLI values of the NX-60, KS-AiN, NM-1, SN60AT and YA-60BBR IOLs decreased with the increase in lens power. Compared to aphakic eyes, currently available UV-blocking clear and yellow-tinted IOLs reduce the BLI values by 43-82%. However, the data presented in this study are not directly applicable to humans implanted with IOLs or for the use of IOLs in a clinical situation, since in those cases the balance between photoprotection and photoreception must be taken into account.