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Peter Rosen, Amir Marvasti, Erwin R Boer, Mauro Della Penna, Robert N Weinreb, Linda M Zangwill, Anna Silverman, Felipe A Medeiros; A Mobile Platform for Evaluation of Processing Speed and Divided Attention at Varying Contrast Levels in Glaucoma Patients. Invest. Ophthalmol. Vis. Sci. 2014;55(13):5645.
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Deficits in visual processing speed, divided attention and contrast sensitivity are the main factors associated with vision-related impairment in the ability to perform everyday tasks, such as driving. We present a new methodology of evaluating visual processing speed under divided attention (VPSDA) at varying contrast levels using a mobile platform (iPad) that allows for easy and effective assessment of functional impairment in glaucoma.
The study included 43 patients with glaucoma and 33 control subjects with mean age of 69 ± 12 and 62 ± 13 years, respectively (P=0.01). Glaucomatous subjects had repeatable defects on standard automated perimetry in at least 1 eye (average MD in the better eye: -4.6 ± 5.6dB). The VPSDA test consisted of recognizing the orientation of a centrally presented tumbling E, while also identifying the location of a peripheral target (Gabor patch), within a limited presentation time. Target presentation was followed by target orientation and localization choices (8-alternative forced choice task). The test was performed at varying Weber contrast levels (100%, 25%, 10% and 5%). All testing was implemented on an iPad mobile platform. In addition, subjects also performed the Useful Field of View test (UFOV) and answered the National Eye Institute visual function questionnaire (NEI-VFQ-25) for assessment of functional impairment. A composite score was calculated from NEI-VFQ responses.
Glaucoma patients exhibited significantly slower processing speed under a divided attention task at all contrast levels when compared to the control group. For 25% contrast, VPSDA was 604 ± 447 vs. 166 ± 233ms in glaucomatous and control subjects, respectively (P<0.001). The VPSDA at 25% contrast performed significantly better than the UFOV to discriminate glaucomatous from controls (age-adjusted ROC curve areas of 0.77 vs. 0.67, respectively). VPSDA at 25% contrast, but not UFOV, was significantly correlated with VFQ-25 composite scores after age-adjustment (P=0.010 and P=0.883, respectively).
The proposed methodology allowed for quick and easy testing of processing speed and divided attention at varying contrast levels and performed better than the traditional UFOV test for identification of functionally impaired glaucoma patients. The mobile platform may allow for effective screening of functional impairment in glaucoma.
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