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Maja G. Erke, Geir Bertelsen, Tunde Peto, Anne K. Sjolie, Inger Njølstad; The Symmetry of Phenotype in Age-related Macular Degeneration. The Tromsø Eye Study. Invest. Ophthalmol. Vis. Sci. 2011;52(14):92.
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To present the symmetry in phenotype between eyes of persons with early and late age-related macular degeneration (AMD) from the Tromsø Eye Study (TES).
TES is a cross-sectional sub-study from the larger Tromsø Study, a longitudinal population study from the municipality of Tromsø, Norway. A random sample of 3025 persons aged 65-87 years old was included for AMD phenotype analysis. Retinal photographs were graded by a single grader trained in the International classification of AMD at Moorfields Eye Hospital Reading Centre. Intra-observer variability was provided by regrading five percent of the sample. Exact agreement was 72% and kappa (Κ) value 0.62.
Among 2481 subjects with gradable images from both eyes, 65% (1624/2481) had bilateral involvement of the same phenotype (Κ value 0.43). When subjects with bilateral normal phenotype, i.e. no drusen or only hard drusen (n=923) were excluded, symmetry was 45% (701/1558) (Κ value 0.16). For individual AMD phenotypes bilateral involvement and age distribution was as follows; 36% (385/1079) for intermediate drusen (63-125µm), median 71, range 65-86 years; 45% (286/642) for soft drusen (>125µm), median 75, range 65-87 years; 40% (12/30) for geographic atrophy, median 76, range 68-82 years and 28% (18/65) for neovascular AMD, median 82, range 73-87 years. For early AMD (drusen larger than 63 µm and no signs of late AMD) the symmetry was 39% (671/1721) and for late AMD symmetry was 32% (30/95). Mean age was significantly higher among subjects with bilateral late AMD compared to subjects with unilateral late AMD (p=0.0453).
The symmetry in phenotype between eyes in persons with early and late AMD was highest for soft drusen larger than 125µm and lowest for neovascular AMD. Median age within symmetry groups was lowest for intermediate drusen and highest for neovascular AMD.
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