Abstract

FR.13.05

Geographic atropy in AMD: Intraindividual symmetry of disease progression and of fundus autofluorence patterns

Fleckenstein M.², Schmitz-Valckenberg S.², Bindewald-Wittich A.², Göbel A. P.², Adrion C.¹, Kampe P.², Scholl H. P. N.², Holz F. G.², Mansmann U.¹, FAM study group
¹Institute for Medical Informatics, Biometry and Epidemiology, LMU, Munich; ²Department of Ophthalmology, University of Bonn

Objective: In the FAM study, longitudinal data of geographic atrophy (GA) progression are recorded prospectively by fundus autofluorescence (FAF) imaging. We could demonstrate that the FAF pattern in the junctional zone of GA that shows a high degree of interindividual variability is a prognostic feature of GA progression. Here, we investigated the degree of intraindividual symmetry in respect of GA progression and the FAF pattern.
Methods: 414 patients were examined with bilateral GA. In 224 patients longitudinal data was available. A hierarchical linear random effects model quantifies the variability of the progression rate and calculates the intraclass correlation coefficient (ICC) as a measure of concordance in between both eyes. The kappa statistic characterises the concordance of the FAF pattern. An ICC- and kappa-value above 0.8 reflect a high degree of concordance.
Results: The standard deviation of the GA progression in between both eyes of a single patient is 0.61 mm²/year, 1.2 mm²/year is the deviation in between patients and 0.99 mm²/year is the deviation due to measuring error. ICC is 0.86 (95% CI [0,81; 0,91]) and therefore confirms a strong concordance in GA progression in between both eyes of a single patient. In 403 of 626 (64.4%) examinations, the FAF pattern could be classified; in 91% of the exams there was the same FAF pattern bilaterally (kappa: 0.77, 95% CI [0.70; 0.84]). In the subgroups of the “diffuse” FAF pattern, in 93.8% of exams there was the same FAF pattern in both eyes (kappa: 0.90, 95% CI [0.86; 0.95]).
Conclusions: GA progression and FAF pattern show a high degree of concordance in between both eyes of a single patient. Intraindividual symmetry in contrast to the high degree of interindividual variability suggests genetic influence on the disease phenotype. Furthermore, these data are relevant for the design, sample size calculations and the implementation of interventional clinical trials aiming on slowing down GA progression in atrophic AMD.

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