Violet light-transmitting intraocular lens increases choroidal thickness: 1-year prospective, randomised controlled trial.

AIMS: To compare the changes in ocular parameters after implantation of two types of intraocular lenses (IOLs) following cataract surgery. One IOL transmits violet light (VL), and the other does not. METHODS: A total of 402 patients were randomly assigned to receive either a VL-non-transmitting IOL or a VL-transmitting IOL. Ocular parameters were measured preoperatively and postoperatively, and participants completed a lifestyle questionnaire. The choroidal thickness (CT) was measured using the PLEX Elite 9000 (Carl Zeiss Meditec). The associations between changes in CT and age, sex, type of IOL, preoperative CT, time spent outdoors, time spent using a smartphone or tablet and time spent reading were examined using stepwise multiple regression analysis (SPSS V.28.0 for Windows, IBM-SPSS). RESULTS: The baseline mean spherical equivalents were -4.00±5.97 D and -2.19±4.73 D, the axial lengths were 24.84±1.82 mm and 24.19±1.65 mm, and the CTs were 213.78±102.93 µm and 239.20±104.98 µm for the VL-non-transmitting and VL-transmitting IOL groups, respectively. The mean changes in the CT from 3 to 12 months postoperatively were -0.30±18.32 µm for the VL-non-transmitting IOLs and 3.48±16.46 µm for the VL-transmitting IOLs (p=0.012). Multiple regression analysis identified significant choroidal thickening associated with female sex (p=0.004), VL-transmitting IOL implantation (p=0.049) and increased outdoor exposure (p=0.008). CONCLUSION: The choroidal thickening after cataract surgery was associated with the VL-transmitting IOL and longer time spent outdoors with exposure to abundant VL. Despite these findings, this study has several limitations, including a relatively short follow-up period, and it did not assess postoperative lifestyle, VL exposure or actual peripheral defocus in the patients. TRIAL REGISTRATION NUMBER: UMIN000038961.