| Popis: |
To conduct a preliminary evaluation of the efficacy of the frequency-doubling contrast test as a means of screening for glaucomatous visual field loss.Contrast thresholds for frequency-doubled stimuli were obtained under four test conditions: superior hemifield, inferior hemifield, and central (5 degrees radius) targets using a method of adjustment (MOA); superior hemifield, inferior hemifield, and central targets using a modified binary search (MOBS); four quadrant stimuli and the central target using MOBS; and 16 stimuli (four per quadrant) and the central target using MOBS. One eye each of 36 patients with early (12), moderate (12), and advanced (12) glaucomatous visual field loss was tested, as was one eye each of 36 age-matched normal control subjects.For hemifield stimuli, the MOBS test procedure had better test-retest reliability, lower individual variation, and greater separation of the normal population and the population with glaucoma than did the MOA procedure. The use of progressively smaller, more localized stimuli produced successively better separation of glaucomatous and age-matched normal control eyes. Area under the Receiver Operating Characteristic curve was 0.81 for hemifield stimuli (sensitivity and specificity, 70% to 75%), 0.91 for quadrant stimuli (sensitivity and specificity, 83% to 85%), and 0.965 for the 16 stimuli (sensitivity 93%, specificity 100%). Test time was approximately 1.3 minutes for hemifields, 1.5 minutes for quadrants, and 5 minutes for the 16 targets.Preliminary results indicate that the frequency-doubled contrast test provides a quick, efficient means of screening for glaucomatous visual field loss. Test time is relatively short, test-retest reliability is good, and sensitivity and specificity for detection of glaucomatous visual field loss is very good. The use of the MOBS staircase procedure and small, localized stimuli result in the best performance for screening purposes. An expanded normative database and the use of more rapid suprathreshold screening strategies should enhance further the efficacy of this test. |
