Amsler vs. Casa: Which Test Better Detects Early Wet AMD?
OCTOBER 14, 2016
Simple at-home vision tests can red flag early signs of wet age-related macular degeneration (AMD). But which one is the best?
Razek Georges Coussa, MD, and colleagues from McGill University in Montréal, Canada set out to answer that very question. The team analyzed the Casa Vision Screener and Amsler Grid to find how well they detected wet AMD. Their findings were presented at the American Academy of Ophthalmology 2016 Annual Meeting (AAO 2016).
Optical coherence tomography (OCT) confirmed an AMD diagnosis in 214 eyes. Then patients were screened with both tests and scores were recorded for sensitivity, specificity, and predictive values (PPV/NPV).
The Amsler Grid involves a graph paper-looking grid where dark lines form a square grid. The Casa Vision Screener has one size Snellen letter 20/40 – the minimum requirement to drive – on a chart with green, red, and yellow background colors.
“Considering presence or absence of subretinal (SRF) or intraetinal fluid (IRF), there was a statistically significant difference between OCT and Amsler but not between OCT and Casa,” the report said. “The PPV and NPV of Amsler and Casa were similar in detecting SRF and IRF.”
On one hand, the Amsler test was 2.5 times more sensitive to SRF/IRF, but the Casa test was 1.6 times better on specificity.
In the first study to compare the Amsler, Casa, and OCT, the researchers found that the Amsler is better for ruling out AMD and the Casa is better for ruling in OCT-based pathology.
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