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Daniel B. Roth, Howard F. Fine, Richard Johnston, Nalin J. Mehta, Jon-Marc Weston; Use of Preferential Hyperacuity Perimetry for Surveillance of Intermediate AMD Eyes at Home. Invest. Ophthalmol. Vis. Sci. 2011;52(14):3542.
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Preferential hyperacuity perimetry (PHP) is used to detect and characterize metamorphopsia. A portable device based upon this technology, was developed for home and frequent monitoring of patients with intermediate age related macular degeneration (AMD) at risk of developing choroidal neovascularization (CNV). Our aim was to evaluate the rate of false positive alerts (FPAs) between clinical visits.
A prospective, observational cohort study of patients with intermediate nonexudative AMD was performed using the home-based PHP device, the ForeseeHome, which examines the macula for central visual field defects and automatically transmits results to a reading center. PHP devices were sent to patients with instructions to test their vision daily for an indefinite period of time, which was logically divided into time units of 6 months. In the first days of use, a baseline of tests was established. When a test change relative to the individual patient’s baseline was detected, the corresponding clinic was alerted and the patient was summoned for an unscheduled visit. If the eye was diagnosed with CNV, the corresponding time unit was counted as true positive, and if CNV was absent, it was counted as false positive. In addition, each eye received standard care with scheduled examinations every 6 months. If the eye was diagnosed with CNV at a scheduled visit without an alert, this time unit was counted as false negative; otherwise as true negative. In case of true positive, false positive or false negative, the study was terminated for this eye.
49 eyes in 36 patients were tested with the preferential hyperacuity perimeter for a median period of 347 days (average frequency of use: 4.12±1.6 tests/week). During this period 5 eyes developed CNV, 3 of which were detected in unscheduled visits triggered by FH alerts. The rate of FPAs between visits was 4% (3 FPAs in 75 time units of 6 months each). The rate of FPAs between visits would be 2% or 7% if the interval between scheduled visits was 3 months or 1 year, respectively. Due to FPAs, the average number of annual visits per eye increased from 4 to 4.08 (3 months interval between visits), 2 to 2.11 (6 months interval) or 1 to 1.18 (1 year interval).
Preferential hyperacuity perimetry is a useful tool for monitoring the vision of intermediate AMD patients at home, with a low rate of FPAs between clinical visits. This rate is marginally dependent on the interval between scheduled visits.
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