Abstract
Objective:To evaluate diagnostic accuracy of a new self-monitoring device using a Vernier hyperacuity alignment task.Method:A total of 11 wet Age-Related Macular Degeneration (AMD) patients and 9 controls contributing 37 eyes were consecutively enrolled into this prospective diagnostic case-control study at the retina centre of the Cantonal Hospital Lucerne, Switzerland. Vernier acuity testing (index test) and Optical Coherence Tomography (OCT, reference test) were performed in all participants. OCT scans were evaluated and graded by a retinal specialist masked to diagnosis and index test results. Candidate parameters of the index test to be used as the diagnostic statistic were identified using a bootstrap procedure. Ten parameters remaining were further assessed in univariate analyses. The overall Standard Deviation (SD) of absolute distances across all four axes of the Vernier acuity test provided the highest area under the Receiver Operating Characteristics (ROC) curve and was therefore selected.Results:Mean age of patients with wet AMD was 81.2 years (SD 4.99), mean numbers of letters were 67.4 (SD 14.1). The proportion of women was similar in both groups (controls: 88%, wet AMD: 72%). The area under the ROC curve was 0.87 (95% confidence interval CI: 0.75- 0.99) indicating excellent discrimination. Best accuracy was reached at a cut-off value of 0.64 with a sensitivity of 75% and a specificity of 94%.Conclusion:This diagnostic case-control study of a new screening device for AMD shows acceptable diagnostic accuracy. The promising preliminary data of this study call for further upstream evaluations in reasonably sized clinical studies.
Highlights
The availability of highly effective new treatment modalities in wet AMD have re-fuelled the discussion about the importance of early identification and targeted patient monitoring [1, 2]
Crossland and Rubin already proclaimed the need of mobile screening devices in 2007 and Loewenstein and co-workers showed in a randomised controlled trial that visual acuity was better preserved using a home monitoring system compared to standard care [3, 5]
We are only aware of several self-monitoring technologies, i.e. one developed by Loewenstein based on Preferential Hyperacuity Perimeter (PHP) [4] (ForeseeHome®), one by Chhetri et al [9] used in a health management tool by Kaiser et al [6]
Summary
The availability of highly effective new treatment modalities in wet AMD have re-fuelled the discussion about the importance of early identification and targeted patient monitoring [1, 2]. This could be achieved with a mobile screening and monitoring device that is easy to handle and valid in the hands of a patient. To date, the Amsler grid is still one of the most frequently used and recommended self-monitoring tests in clinical practice. The lack of a simple test that could be performed at home may lead to unnecessary delay of diagnosis, in the extreme case at a stage, where permanent vision loss due to retinal damage has already occurred
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