Abstract
Purpose :
Blue light is important for different aspects of vision. Scotopic sensitivity has its maximum at blue wavelengths (Mainster et al. AJO 2009). Blue light is also essential for healthy circadian rhythms, which affect sleep pattern, mood, and overall systemic health (Mainster et al BJO 2006). Therefore, intraocular lenses (IOLs) that block the high-energy violet part of the visible spectrum without compromising any of these aspects have become available. The purpose of this research is to evaluate the optical and visual performance of a violet blocking IOL that retains the full transmission of blue light.
Methods :
Preclinical and clinical assessments were performed with IOLs having the same monofocal aspheric design made from two different materials, a clear material that blocks ultraviolet radiation and a violet blocking material that in addition filters up to 425 nm. Preclinical assessment included optical bench testing of modulation transfer function (MTF) as well as computer simulations of halo intensity with different light sources. A randomized clinical study was performed in 240 patients bilaterally implanted with these IOLs. Endpoints included visual acuity, as well as non-directed dysphotopsia reports and directed questionnaire on functional experience.
Results :
Optical bench testing resulted in the same MTF at 50cpmm for clear and violet blocking IOLs. Computer simulations showed that blue light sources produce a halo with higher intensity than white light sources. For violet blocking IOLs, there was an approximately 50% reduction in the halo intensity for blue light when compared to clear IOLs. Clinical results did not show significant difference in best-corrected distance visual acuity and in reports of halo and glare after 1 year. The directed questionnaire showed that patients with violet blocking IOLs had significantly less difficulty with driving during daytime (p=0.033) and nighttime (p=0.017). In addition, a higher percentage of patients implanted with violet blocking IOLs reported no frustration with vision (p= 0.0325).
Conclusions :
We compared the optical quality and visual performance provided by violet blocking and clear IOLs of the same lens design. While MTF was the same, simulated halo performance with blue light was better for violet blocking IOLs. In addition, clinical data showed superior outcomes of the violet blocking IOL for subjective responses on several aspects of functional experience.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.