Abstract
Abstract: :
Purpose: To determine the utility of the Frequency Doubling Perimetry Test (FDT) for screening for glaucoma in a rural, developing world setting. Methods: FDT (C-20-5 screening protocol), best-corrected visual acuity, tonometry, anterior segment biomicroscopy, grading of cataract with the Lens Opacities Grading System (LOCS), and dilated ophthalmoscopy was performed in participants over 35 years old in South Indian villages near Madurai. If there was an abnormal location or an unreliable result, the FDT was repeated. Excluding other ocular disease and unreliable visual fields, a repeatable, abnormal FDT was defined as one abnormal location on the FDT printout present in the initial and repeat examination. An abnormal optic nerve was defined as a cup to disc ratio of greater than 0.5 or glaucomatous features. Results: There were 296 participants (592 eyes) tested over three days with a single FDT machine. 19% of eyes were unreliable with initial FDT testing but only 5% had a repeatable, unreliable FDT. Using one eye for analysis determined by worsening optic disc appearance, 2.4% of eyes had an abnormal optic nerve and a repeatable, abnormal FDT. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of FDT for an abnormal optic nerve was 11%, 87%, 19%, 76%, and 69%, respectively. Conclusion: The FDT can be used to screen large numbers of persons for glaucoma rapidly with reliable results. In this type of setting, it has good specificity but low sensitivity. Therefore, the utility of a single screening test for glaucoma may be limited.
Keywords: 624 visual fields • 511 perimetry • 356 clinical (human) or epidemiologic studies: systems/equipment/techniques