title: Retinal vascular caliber, iris color, and age-related macular degeneration in the Irish Nun Eye Study.
abstract: OBJECTIVE
  To evaluate the relationship between retinal vascular caliber (RVC), iris color, and age-related macular degeneration (AMD) in elderly Irish nuns.
  
  
  METHODS
  Data from 1233 participants in the cross-sectional observational Irish Nun Eye Study were assessed from digital photographs with a standardized protocol using computer-assisted software. Macular images were graded according to the modified Wisconsin Age-related Maculopathy Grading System. Regression models were used to assess associations, adjusting for age, mean arterial blood pressure, body mass index, refraction, and fellow RVC.
  
  
  RESULTS
  In total, 1122 (91%) participants had gradable retinal images of sufficient quality for vessel assessment (mean age: 76.3 years [range, 56-100 years]). In an unadjusted analysis, we found some support for a previous finding that individuals with blue iris color had narrower retinal venules compared to those with brown iris color (P < 0.05), but this was no longer significant after adjustment. Age-related macular degeneration status was categorized as no AMD, any AMD, and late AMD only. Individuals with any AMD (early or late AMD) had significantly narrower arterioles and venules compared to those with no AMD in an unadjusted analysis, but this was no longer significant after adjustment. A nonsignificant reduced risk of any AMD or late AMD only was observed in association with brown compared to blue iris color, in both unadjusted and adjusted analyses.
  
  
  CONCLUSIONS
  Retinal vascular caliber was not significantly associated with iris color or early/late AMD after adjustment for confounders. A lower but nonsignificant AMD risk was observed in those with brown compared to blue iris color.
authors.affiliation: Centre for Public Health, Queen's University Belfast, Belfast, Northern Ireland.
authors.forename: Amy
authors.initials: A
authors.lastname: McGowan
authors.affiliation: Centre for Experimental Medicine, Queen's University Belfast, Belfast, Northern Ireland.
authors.forename: Giuliana
authors.initials: G
authors.lastname: Silvestri
authors.affiliation: Department of Ophthalmology, Royal Victoria Hospital, Belfast, Northern Ireland.
authors.forename: Evelyn
authors.initials: E
authors.lastname: Moore
authors.affiliation: Department of Ophthalmology, Royal Victoria Hospital, Belfast, Northern Ireland.
authors.forename: Vittorio
authors.initials: V
authors.lastname: Silvestri
authors.affiliation: Centre for Public Health, Queen's University Belfast, Belfast, Northern Ireland.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Patterson
authors.affiliation: Centre for Public Health, Queen's University Belfast, Belfast, Northern Ireland.
authors.forename: Alexander P
authors.initials: AP
authors.lastname: Maxwell
authors.affiliation: Centre for Public Health, Queen's University Belfast, Belfast, Northern Ireland.
authors.forename: Gareth J
authors.initials: GJ
authors.lastname: McKay
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005127:Eye Color; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007494:Ireland / Q000453:epidemiology; D007498:Iris / Q000503:physiopathology*; D008268:Macular Degeneration / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D008875:Middle Aged; D065831:Nuns; D015995:Prevalence; D012171:Retinal Vessels / Q000473:pathology*
keywords: age-related macular degeneration; iris color; retinal vascular caliber