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B Madsen, WE Sponsel, S McKinnon; Evaluation of VisionRx Computer Based Perimetry vs. Humphrey Visual Field . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2174.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To investigate the potential use of VisionRx computer based perimetry technology to measure visual field defects in patients with and without glaucomatous disease. Methods:Patients with and without scotomata were asked to complete both 24-2 SITA full-threshold Humphrey 24-2 and VisionRx computer based perimetry. Results:50 eyes of 50 different patients were initially analyzed. 24 eyes of 24 patients that satisfied standard reliability criteria on both perimetry tests were compared (age range 14-72; 12 normals, 5 glaucoma suspects, 7 glaucomas). The average time required to complete the SITA standard threshold HVF was 6 min vs. 14 min for VisionRx computerized perimetry (P<0.001). Older patients unfamiliar with computers had more difficulty than younger patients in performing VisionRx testing, mainly as a consequence of their unfamiliarity with the use of a mouse, the stimulus response device. 1246 loci (24 subjects, 54 loci minus the blind spot) on both the VisionRx and HVF were analyzed. A fairly uniform mean difference was observed, with thresholds 7.07 +/- 0.16 dB lower on VisionRx than HVF at comitant loci across the visual field. After applying a -7 dB correction factor for each locus on the VisionRx, masked comparison of both sets of visual fields was performed using Hodapp/Parish/Anderson criteria, demonstrating the following indices for VisionRx vs HVF 24-2 gold standard: [Subgroup (True +/True -/False +/False -:in %)]: Normals (0/92/8/0); Suspects (20/60/20/0); Glaucoma (71/14/14//0). Overall concordance was 88%, with 13% false positives and 0 false negatives. Sensitivity was 100% and specificity 83%. Regional correspondence of scotoma location and size existed between perimeters. Conclusion: This comparison suggests that VisionRx perimetry may be a good screening tool for certain populations. According to the Baltimore Eye Study, at age 55, 5% of the African American population is likely to have glaucoma. According the specificity above, VisionRx perimetry would give approximately a 3:1 ratio of false positives to true positives with 100% sensitivity among this group, a good screening ratio. In the Caucasion population at age 55 there is < 2% prevalence of glaucoma. VisionRx would produce an 8:1 false positive to true positive ratio among this group, somewhat high for a screening exam, even one with 100% sensitivity. The current version of VisionRx perimetry is thus a potentially useful screening tool for high prevalence populations adept at using computers. It can also spatially quantify pathology among patients with existing disease, allowing clinic-linked home monitoring of visual field change via the internet.
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