Retinal arteriolar and venular calibers were measured using Interactive Vessel ANalysis software (IVAN University of Wisconsin, Madison, WI, USA) according to a standardized protocol for all retinal vessels located between a half and one disc diameter distance from the optic disc margin in the digitized image. These features were used to assign each eye to a severity grade as follows: no AMD, no features of AMD or the presence of soft distinct drusen (>63 and ≤125 μm) or pigmentary abnormalities only early AMD, soft, indistinct (≥125 μm), or reticular drusen only or soft distinct drusen with pigmentary abnormalities late AMD, either geographic atrophy (well-demarcated area of retinal pigment atrophy with visible choroidal vessels) or neovascular AMD (presence of any of the following: serous or hemorrhagic retinal or retinal pigment epithelial detachment, subretinal neovascular membrane, or periretinal fibrous scar). Pigmentary changes were classified into two categories, hyperpigmentation and hypopigmentation. Drusen were classified according to size, characteristics of homogeneity of surface features, and outline. 27 The presence of features within a 6000-μm circle centered on the fovea was recorded. 26 The definitions for AMD were based on the International Classification for Age-related Macular Degeneration. Anonymized images were submitted to NetwORC UK, and trained graders followed a standardized procedure to identify the characteristics of early and late AMD using the definitions of the Wisconsin Age-related Maculopathy Grading System. A lower but nonsignificant AMD risk was observed in those with brown compared to blue iris color.Īll images were independently graded by the Network of Ophthalmic Reading Centres UK (NetwORC UK) in Belfast. Retinal vascular caliber was not significantly associated with iris color or early/late AMD after adjustment for confounders. 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. 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. Age-related macular degeneration status was categorized as no AMD, any AMD, and late AMD only. 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. In total, 1122 (91%) participants had gradable retinal images of sufficient quality for vessel assessment (mean age: 76.3 years ). Regression models were used to assess associations, adjusting for age, mean arterial blood pressure, body mass index, refraction, and fellow RVC. Macular images were graded according to the modified Wisconsin Age-related Maculopathy Grading System. To evaluate the relationship between retinal vascular caliber (RVC), iris color, and age-related macular degeneration (AMD) in elderly Irish nuns.ĭata 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.
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