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Y Trigo, M Pena, G Paris, WE Sponsel; AAO/VFW Eye Screening 2001; Diagnostic Power of First-pass Intraocular Pressure Measurement versus First-pass Frequency Doubling Technology . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3325.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:To assess the utility of IOP versus FDT for detecting concomitant optic nerve pathology and visual field loss, applying the cumulative database of 4 AAO-sponsored eye screenings at Veterans of Foreign Wars (VFW) National Conventions (1998-2001). Methods: All Health Fair attendees underwent visual acuity and FDT testing in yrs 1-4 (1998-2001). In yr 4 (2001) all eyes underwent immediate applanation tonometry, as well. In yrs 1-4, all participants with acuity less than 20/40, or two or more misses on FDT C-20-5, underwent slit lamp and ophthalmoscopic exam, as did those with IOP ≥21 in yr 4. Humphrey 24-2 SITA threshold perimetry was performed on all eyes failing FDT testing in yrs 1-4, and also, in yr 4, on all eyes with IOP ≥21 mm Hg. Results:2104 self-referred individuals were screened; ∼500 per year (2:1 ratio M:F; mean age 70 yrs): 284 (13% of the population tested) failed FDT and demonstrated nerve fiber layer type visual field defects on Humphrey 24-2 analysis. The cumulative false positive rate for FDT relative to HVF was 5% (16/300). Among those failing both perimetry tests submitting to stereo disc assessment, 85% showed morphologic evidence of optic neuropathy on digital or scanning laser tomography. Thus, approximately 11% of the veterans who referred themselves for screening over years 1-4 demonstrated some degree of concomitant visual field loss and optic nerve cupping. Cumulatively in years 1-4, among those failing both visual field assessments, only 47 had IOP’s ≥21 mmHg in either eye (i.e. 47/284; or 17% of those with confirmed visual field defects, just 2.2% of a population with an apparent 11% pathologic index).In 2001, tonometry was performed on all 535 subjects screened, and either an IOP ≥21 or FDT failure triggered HVF 24-2 acquisition. The positive predictive value of IOP≥21 for an abnormal HVF that year was 13% (9/67); for FDT it was 97% (65/67). The true positive rate for IOP ≥21 was 29% (9/31), and for FDT was 92% (65/71). False positive rate for IOP≥21 was thus 58% (18/31). Adopting a higher IOP screening cutoff progressively decreased the net positive yield, with little improvement in true positive rate (8/27, 6/11, 5/9, 4/7 for IOPs≷23,24,25,26). In 2001, IOP≥21 detected 1 probable diseased subject who did not fail FDT, while FDT detected 57 who would have been missed by tonometry. Conclusion: The utility of first-pass perimetry at eye screenings was shown at VFW health fairs in San Antonio (1998), Kansas City (1999), and Milwaukee (2000-01). IOP screening was reaffirmed as a dismal means for predicting likely glaucoma, regardless of the IOP cutoff value used.
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