title: The effect of blue-blocking intraocular lenses on circadian biological rhythm: protocol for a randomised controlled trial (CLOCK-IOL colour study).
abstract: BACKGROUND
  Blue light information plays an important role in synchronising internal biological rhythm within the external environment. Circadian misalignment is associated with the increased risk of sleep disturbance, obesity, diabetes mellitus, depression, ischaemic heart disease, stroke and cancer. Meanwhile, blue light causes photochemical damage to the retina, and may be associated with age-related macular degeneration (AMD). At present, clear intraocular lenses (IOLs) and blue-blocking IOLs are both widely used for cataract surgery; there is currently a lack of randomised controlled trials to determine whether clear or blue-blocking IOLs should be used.
  
  
  METHODS
  This randomised controlled trial will recruit 1000 cataract patients and randomly allocate them to receive clear IOLs or blue-blocking IOLs in a ratio of 1:1. The primary outcomes are mortality and the incidence of cardiovascular disease, cancer and AMD. Secondary outcomes are fasting plasma glucose, triglycerides, cholesterol, glycated haemoglobin, sleep quality, daytime sleepiness depressive symptoms, light sensitivity, the circadian rhythm of physical activity, wrist skin temperature and urinary melatonin metabolite. Primary outcomes will be followed until 20 years after surgery, and secondary outcomes will be assessed at baseline and 1 year after surgery.
  
  
  BACKGROUND
  Ethical approval has been obtained from the Institutional Review Board of Nara Medical University (No. 13-032). The findings of this study will be communicated to healthcare professionals, participants and the public through peer-reviewed publications, scientific conferences and the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) home page.
  
  
  BACKGROUND
  UMIN000014680.
authors.affiliation: Department of Ophthalmology, Nara Medical University School of Medicine, Nara, Japan.
authors.forename: Tomo
authors.initials: T
authors.lastname: Nishi
authors.affiliation: Department of Community Health and Epidemiology, Nara Medical University School of Medicine, Nara, Japan.
authors.forename: Keigo
authors.initials: K
authors.lastname: Saeki
authors.affiliation: Department of Community Health and Epidemiology, Nara Medical University School of Medicine, Nara, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Obayashi
authors.affiliation: Department of Ophthalmology, Nara Medical University School of Medicine, Nara, Japan.
authors.forename: Kimie
authors.initials: K
authors.lastname: Miyata
authors.affiliation: Center for Academic Industrial and Governmental Relations, Nara Medical University School of Medicine, Nara, Japan.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Tone
authors.affiliation: Department of Ophthalmology, Nara Medical University School of Medicine, Nara, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Tsujinaka
authors.affiliation: Department of Ophthalmology, Nara Medical University School of Medicine, Nara, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Yamashita
authors.affiliation: Department of Ophthalmology, Nara Medical University School of Medicine, Nara, Japan.
authors.forename: Naonori
authors.initials: N
authors.lastname: Masuda
authors.affiliation: Department of Ophthalmology, Nara Medical University School of Medicine, Nara, Japan.
authors.forename: Yutarou
authors.initials: Y
authors.lastname: Mizusawa
authors.affiliation: Department of Ophthalmology, Nara Medical University School of Medicine, Nara, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Okamoto
authors.affiliation: Department of Ophthalmology, Nara Medical University School of Medicine, Nara, Japan.
authors.forename: Taiji
authors.initials: T
authors.lastname: Hasegawa
authors.affiliation: Department of Ophthalmology, Nara Medical University School of Medicine, Nara, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Maruoka
authors.affiliation: Department of Ophthalmology, Nara Medical University School of Medicine, Nara, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Ueda
authors.affiliation: Department of Ophthalmology, Nara Medical University School of Medicine, Nara, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Kojima
authors.affiliation: Department of Ophthalmology, Nara Medical University School of Medicine, Nara, Japan.
authors.forename: Toyoaki
authors.initials: T
authors.lastname: Matsuura
authors.affiliation: Department of Community Health and Epidemiology, Nara Medical University School of Medicine, Nara, Japan.
authors.forename: Norio
authors.initials: N
authors.lastname: Kurumatani
authors.affiliation: Department of Ophthalmology, Nara Medical University School of Medicine, Nara, Japan.
authors.forename: Nahoko
authors.initials: N
authors.lastname: Ogata
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D002386:Cataract / Q000628:therapy*; D002387:Cataract Extraction; D002940:Circadian Rhythm; D002985:Clinical Protocols; D003116:Color; D006801:Humans; D007910:Lenses, Intraocular / Q000009:adverse effects; D008027:Light / Q000009:adverse effects; D008268:Macular Degeneration / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D008875:Middle Aged; D009369:Neoplasms / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D012107:Research Design
keywords: ONCOLOGY