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New light for old eyes: comparing melanopsin-mediated non-visual benefits of blue-light and UV-blocking intraocular lenses
  1. Conrad Schmoll1,
  2. Ashraf Khan1,
  3. Peter Aspinall2,
  4. Colin Goudie1,
  5. Peter Koay1,
  6. Christelle Tendo1,
  7. James Cameron1,
  8. Jenny Roe2,
  9. Ian Deary3,
  10. Bal Dhillon4
  1. 1Princess Alexandra Eye Hospital, Edinburgh, UK
  2. 2VisionCentre3, OPENspace, School of the Built Environment, Heriot-Watt University, Edinburgh, UK
  3. 3Department of Psychology, Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, UK
  4. 4Department of Clinical Science, University of Edinburgh, Edinburgh, UK
  1. Correspondence to Dr Conrad Schmoll, Princess Alexandra Eye Pavilion, 45 Chalmers Street, Edinburgh EH3 9HA, UK; conradschmoll{at}


Background/aims Melanopsin-expressing photosensitive retinal ganglion cells form a blue-light-sensitive non-visual system mediating diverse physiological effects including circadian entrainment and cognitive alertness. Reduced blue wavelength retinal illumination through cataract formation is thought to blunt these responses while cataract surgery and intraocular lens (IOL) implantation have been shown to have beneficial effects on sleep and cognition. We aimed to use the reaction time (RT) task and the Epworth Sleepiness Score (ESS) as a validated objective platform to compare non-visual benefits of UV- and blue-blocking IOLs.

Methods Patients were prospectively randomised to receive either a UV- or blue-blocking IOL, performing an RT test and ESS questionnaire before and after surgery. Optical blurring at the second test controlled for visual improvement. Non-operative age-matched controls were recruited for comparison.

Results 80 participants completed the study. Those undergoing first-eye phacoemulsification demonstrated significant improvements in RT over control (p=0.001) and second-eye surgery patients (p=0.03). Moreover, reduced daytime sleepiness was measured by ESS for the first-eye surgery group (p=0.008) but not for the second-eye group (p=0.09). Choice of UV- or blue-blocking IOL made no significant difference to magnitude of cognitive improvement (p=0.272).

Conclusions Phacoemulsification, particularly first-eye surgery, has a strong positive effect on cognition and daytime alertness, regardless of IOL type.

  • Physiology
  • Retina

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