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J. S. Kroisamer, R. Sayegh, C. Simader, U. Scheschy, C. Kiss, C. Prünte, U. Schmidt-Erfurth; Characteristics of Fixation in Patients with Geographic Atrophy Recorded with the MP-1 Microperimeter. Invest. Ophthalmol. Vis. Sci. 2010;51(13):315.
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The aim of this observational study was to evaluate fixation patterns in eyes with geographic atrophy (GA) secondary to AMD with the help of the MP-1 microperimeter.
Static threshold perimetry including fixation evaluation was performed in 50 eyes with geographic atrophy using MP1 microperimetry (Nidek Technologies, software version 1.4.2).Based on Fujii et al. [Ophthalmology 1999, 109(9)] fixation was classified as "Stable" if more than 75% of the fixation points were inside a 2° diameter circle, as "Relatively Unstable" if more than 75% of the fixation points were inside a 4° diameter circle and less than 75% were inside the 2° diameter circle and as "Unstable" if less than 75% of the fixation points were inside the 4° diameter circle.To determine the correct position of the fovea, the foveal region was marked on patients' Spectralis-OCT image. The corresponding SLO image was overlayed with the IR fundus image obtaind by the MP1. Fixation was classified based on the percentage of fixation points lying inside a 2° foveal circle as "Predominantly Central" (>50%), as "Poor Central" (>25% and <50%) and as "Predominantly Eccentric" (<25%). In patients with predominantly eccentric fixation the location of the preferred retinal locus for fixation (PRL) was determined.
Baseline fixation characteristics of the patients enrolled in the study are the following: Predominantly Central (8%): Stable (100%), Relatively Unstable (0%), Unstable (0%); Poor Central (0%); Predominantly Eccentric (92%): Stable (10.87%), Relatively Unstable (36.96%), Unstable (52.17%);The new PRL was located superior-left (36.96%), superior (28.26%), at the left (19.57%) or superior-right (15.22%) to the atrophy at the fundus image. No patient showed a PRL located at the other four segments.
Microperimetry is an appropriate modality to evaluate fixation pattern in patients with GA. There is a preference for eccentric fixation superior and at the left to the atrophy when looked at the retina.
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