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Paul C Knox, Noelia Pitrelli Vazquez, Simon P Harding, Heinrich Heimann, Gabriela Czanner; Diagnostic performance of the handheld Radial Shape Discrimination test for detecting recent onset neovascular age-related macular degeneration. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2345. doi: https://doi.org/.
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The advent of effective treatments for neovascular age-related macular degeneration (nAMD) means that improved, cost-effective methods of detection and monitoring of patients are required. We have investigated the sensitivity and specificity of the handheld Radial Shape Discrimination test (hRSD; Wang et al, 2013, IOVS 54:5479) which has shown potential for the early detection of nAMD.
Patients diagnosed with, and receiving treatment for, nAMD in their first eye, and with no evidence of nAMD in their fellow eye (the study eye, SE) were recruited. We excluded patients with Diabetes, or geographic atrophy close to the macula. An hRSD test (3AFC version, presented on an Apple iPod Touch) was completed with both eyes on consecutive, routine, clinic visits from recruitment up to a maximum of 12 occasions, or until nAMD was diagnosed in the SE. Diagnosis was based on masked clinician assessment using biomicroscopy and spectral domain OCT, confirmed with fluorescein angiography. For each patient the result of the hRSD test in the SE at the final visit (the conversion visit for those who developed nAMD) was used for ROC analysis.
Of 184 patients recruited (mean±SD age: 78±8 years; range: 52-93 years, 109 female), 21 (11%) developed nAMD in the SE (converters). hRSD threshold at the final study visit differed significantly between converters (-0.45±0.19logMAR) and non-converters (-0.60±0.19logMAR; t=3.46, df=182 p<0.001). The area under the ROC curve (AUC; see Figure) for the hRSD test, for differentiating converters from non-converters, was 0.73 (95%CI 0.62 to 0.83), significantly different from an AUC of 0.5 (p=0.001). At a cut-off value of -0.57logMAR, hRSD test sensitivity for detecting new nAMD was 81% with a specificity of 60%.
The hRSD test demonstrated sensitivity for detecting the development of new nAMD superior to that of time domain OCT, Amsler grid and PHP hyperacuity as reported by Do et al, 2012, Ophthalmology 119:771, who used a similar prospective study design, following the fellow eyes of patients being treated for nAMD in the first eye. Given these data, the ease of test use and its low cost, the hRSD test may have value in the early detection of nAMD leading to earlier diagnosis and treatment.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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