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Editors Selection IGR 16-3
Prevention and Screening: An iPad App to Detect Visual Field Loss
Comment by Ivan Goldberg on:
74230 Performance of an iPad Application to Detect Moderate and Advanced Visual Field Loss in Nepal, Johnson CA; Thapa S; George Kong YX et al., American Journal of Ophthalmology, 2017; 182: 147-154
As the authors point out, visual field loss from glaucoma is progressive and irreversible and mostly asymptomatic till advanced; this results in the appalling 50 - 60% non-detection rate in developed societies, rising to over 90% in developing communities. Early detection is vital if glaucomatous visual disability is to be minimized, or eliminated.
Community screening has not proved viable unless the screened population is "enriched" (e.g. family members of diagnosed persons) and/or other eye or even other health issues are included. Attempts to improve early detection with opportunistic screening have been disappointing.
Hence efforts abound to use technological advances to improve screening: use of smartphone- captured images of optic discs with telemedicine-assisted remote assessment and use of e-tablets to measure visual sensitivity. Johnson et al. describe a new, free, downloadable App to do just this - Visual Fields Easy (VFE).
Their setting was the famous Tilganga Eye Center in Kathmandu; their method, to test 210 normal, 183 glaucoma and 18 diabetic retinopathy eyes with the new App and to compare results with those from the 24-2 Humphrey SITA Standard for 373 of those eyes. Missed locations with the VFE correlated reasonably with the Humphrey Mean Deviation (MD, r = 0.79), particularly for those eyes with MD less than -6D (moderate-to-advanced damage). A raised false positive response rate was thought contributory to poorer VFE results with mild damage. Believing that better control of eye-to-iPad distance along with monitoring of fixation, reduction in the number of tested points (currently 96, with a testing time too long at over 3 minutes), finding a way for participants to avoid touching the screen (producing smudges) and re-testing missed points, the authors believe will overcome many challenges.
Refinements like these would enable more effective screening, and offer home tonometry for treated glaucoma sufferers, thereby enhancing quality of care. We keenly await these advances.Comments
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