Automated suprathreshold screening for glaucoma: the Baltimore Eye Survey.

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Abstract

PURPOSE: To evaluate automated suprathreshold perimetric screening for glaucoma in a population-based survey of ocular disorders in east Baltimore, Maryland. METHODS: A population-based sample of persons > or = 40 years of age residing in 16 clusters was selected for an ocular screening examination that included automated suprathreshold testing with the Full Field 120 program of the Humphrey Field Analyzer. Subjects who failed the test underwent manual testing to confirm the defect. Subjects were referred for definitive examination by an ophthalmologist if they had an abnormal field, visual acuity worse than 20/30, intraocular pressure > 21 mm Hg, optic disc damage, a history of glaucoma, or shallow angles. The sensitivity and specificity of the automated visual field testing for identifying glaucoma was estimated and compared with other methods to screen for glaucoma. RESULTS: Of 5,341 subjects > or = 40 years of age who underwent a screening eye examination at neighborhood centers, 4,735 (89%) completed the automated field test. The median test time was 7.25 minutes per eye. Screening test results were abnormal in one or both eyes in 1,234 (26%) of the subjects. Kinetic perimetry was performed on 95% of these subjects, and defects were confirmed for 448 (36%) of them. Hence, 9.5% of the 4,735 subjects who completed the automated test were referred for definitive examination because the defect on automated perimetry was confirmed on manual testing. For a specificity of 90%, the sensitivity of the screening visual field test to detect glaucoma was 52% for 17 or more relative or absolute defects, higher than that of intraocular pressure at 39% for a cut-off of 20.5 mm Hg, vertical cup-to-disc ratio at 45% for a cut-off of 0.53, narrowest remaining rim width at 42% for a cut-off of 0.16, and was comparable to a combination of these and other nonfield parameters. CONCLUSION: Suprathreshold testing performed better than nonperimetry-based screening tests for glaucoma. However, a number of logistical weaknesses of this visual field screening method were identified.