title: New light for old eyes: comparing melanopsin-mediated non-visual benefits of blue-light and UV-blocking intraocular lenses.
abstract: OBJECTIVE
  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.
authors.affiliation: Princess Alexandra Eye Hospital, , Edinburgh, UK.
authors.forename: Conrad
authors.initials: C
authors.lastname: Schmoll
authors.forename: Ashraf
authors.initials: A
authors.lastname: Khan
authors.forename: Peter
authors.initials: P
authors.lastname: Aspinall
authors.forename: Colin
authors.initials: C
authors.lastname: Goudie
authors.forename: Peter
authors.initials: P
authors.lastname: Koay
authors.forename: Christelle
authors.initials: C
authors.lastname: Tendo
authors.forename: James
authors.initials: J
authors.lastname: Cameron
authors.forename: Jenny
authors.initials: J
authors.lastname: Roe
authors.forename: Ian
authors.initials: I
authors.lastname: Deary
authors.forename: Bal
authors.initials: B
authors.lastname: Dhillon
mesh_terms: D000368:Aged; D002386:Cataract / Q000503:physiopathology*; D002940:Circadian Rhythm / Q000502:physiology; D003071:Cognition / Q000502:physiology*; D005260:Female; D006801:Humans; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008027:Light; D008297:Male; D018918:Phacoemulsification; D011446:Prospective Studies; D011930:Reaction Time / Q000502:physiology; D012044:Regression Analysis; D017299:Rod Opsins / Q000502:physiology*; D012890:Sleep / Q000502:physiology*; D011795:Surveys and Questionnaires; D000099210:Melanopsin
chemical_list: D017299:Rod Opsins; D000099210:Melanopsin
keywords: Physiology; Retina