Autor:innen:
Alexandra Steinemann (Basel | CH)
Vivien Bromundt (Bern | CH)
Sarah L. Chellappa (Bosten | US)
Sylvia Frey (Basel | CH)
Christian Cajochen (Basel | CH)
Christina Schmidt (Liège | BE)
Torsten Schlote (Basel | CH)
David Goldblum (Basel | CH)
Purpose:
Cataract leads to a decrease in light transmittance. Intra-ocular lens (IOL) replacement aims at restoring optimal spectral transmittance. However, it remains to be fully established whether the beneficial effects of cataract IOLs translate to changes in visual comfort and mental effort during light exposure. Here, we investigated whether IOL replacement (blue-blocking, BB, or ultraviolet-only blocking, UV) in cataract patients improves visual comfort and mental effort, as compared to normal aging adults.
Methods:
Post-cataract patients with intra-ocular BB (n=9; 69.8 ± 6.2y) and UV (n=5; 70.8 ± 4y) lens replacement and healthy older controls (AAC; n=16; 63.6 ± 5.6y) underwent a randomized, within-subject crossover design with 3 in-laboratory protocols 1-week apart. After 3h of prior light exposure control (1.5h under dim light and 1.5h of dark adaptation), they were exposed to 2h of evening polychromatic light at 6500K (blue-enriched), 2500K and 3000K (both non-blue enriched). For each light condition, visual comfort and mental effort were assessed through a Visual Analogue Scale (0 - 100) for Visual Comfort and a Mental Effort Rating Scale (0 - 100).
Results:
Mean vision for UV, BB, and ACC was 0.92±0.18, 0.95±0.09, and 0.93±0.12. With respect to Mental effort, UV and BB patients had significantly higher levels of mental tiredness, as compared to ACC (main effect “group”; F=6.15, p=0.003). However, BB patients had significantly higher levels of motivation, as compared to UV patients and ACC (main effect “group”; F=8.1, p 0.001). With respect to Visual comfort, BB patients had significantly lower levels of perceived ambient light glare, as compared to UV patients and ACC (main effect “group”; F=4.71, p=0.01). Importantly, the interaction of “light condition” vs. “group” yielded a significant effect, such that BB patients had lower levels of visual tension when exposed to blue-enriched ambient light as compared to UV patients and ACC (multiple comparison adjustment; F=2.51, p=0.042).
Conclusion:
Our data indicate that lens replacement may increase visual comfort and minimize mental effort. While subtle, the magnitude of these effects may depend on the type of IOL. BB, in particular, might have potential benefits, as ambient light is perceived having less glare and less visual tension. Different effects of UV and BB on visual comfort and mental effort in older adults are observed.