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A.K. Bittner, F. Baker, D. Mladenovich, G. Dagnelie; Fixation Controlled AVIAS Static Perimetry in Legally Blind RP and MD Patients . Invest. Ophthalmol. Vis. Sci. 2004;45(13):5451.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:To demonstrate a method for obtaining repeatable central visual field measures in subjects with severe vision loss, for use during Phase I experimental trials or routine clinical evaluation. Methods:The AVIAS(Automated Visual Impairment Assessment System) makes use of a head–mounted binocular video display with 60° diagonal field size and built–in fixation monitoring. Fixation targets are presented binocularly and can be placed at any location. Test targets are presented monocularly in random order. Building on a 6x6 grid with 5° spacing and denser test points around fixation, points are added in an interactive procedure. Test parameters and locations are saved for automated retesting during follow–up visits. To assess reliability, we tested subjects four or five times at one month intervals. Subjects included patients with retinitis pigmentosa (field diameters <20°), and age related macular degeneration or Stargardt’s Dystrophy (VA < 20/200). In macular degeneration subjects, results from the AVIAS are compared to a Humphrey visual field. In RP patients, results are compared to those obtained with Goldmann V/4e and II/4e targets, and Humphrey 10–2 fields, each performed 3 to 5 times. Results:A mean radius, area, and 2–sided test–retest 95% confidence interval (CI.95) or coefficient of variation (CoV), were computed for each eye. AVIAS data from 5 RP eyes with mean radius 2.7º to 6.0º, yielded CI.95 <=2 dB, and CoV <=29% for field size. AVIAS data from 2 Stargardt’s and 3 ARMD eyes, showed mean scotoma radius of 7.1º to 18.7º, with scotoma area CI.95 0.9 to 1.7 dB. Subjects’ variability depends upon the disease and visual field loss. Goldmann perimetry in RP patients yielded a mean radius of 3.6º to 7.6º with V/4e (CoV 7.7 to 11.3%), and <=5.2º with II/4e (CoV 2.7 to 9.3%). The mean cumulative threshold for central 8º of Humphrey 10–2 with stimulus size III was 125.3 to 225.7 dB in RP subjects, with mean standard deviation 4.3 to 7.7 dB. Individual field plots and results will be presented. Conclusions: AVIAS perimetry yields data with good repeatability in subjects with fixation difficulty and severe vision loss, and is a useful tool for monitoring changes in scotoma or field size over time.
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