Algorithm for interpreting the results of frequency doubling perimetry

PURPOSE: To evaluate an algorithm for the identification of glaucomatous visual field defects with the screening mode of frequency doubling technology. METHODS: Screening-mode frequency doubling technology and Swedish interactive threshold algorithm perimetry were performed on 137 of 150 consecutive patients referred to a glaucoma specialist. We created an algorithm for the frequency doubling technology that gave increased importance to both more severe defects and defects closer to fixation, These values were then compared with the results of the Swedish interactive threshold algorithm visual fields evaluated by the glaucoma hemifield test, two masked glaucoma specialists, and a published definition of glaucomatous damage to determine sensitivity and specificity of the frequency doubling technology screening mode for detecting glaucoma. RESULTS: The frequency doubling technology score obtained with our algorithm had a sensitivity of 80% or more and specificity of 93% or more irrespective of the criteria for defining glaucoma. Sensitivity increased to 95% in detecting moderate or severe field loss without a compromise in specificity. All subjects with normal visual fields completed the frequency doubling technology examination within 90 seconds. In most cases, eyes were abnormal if they had two peripheral defects or one central defect. CONCLUSIONS: Our frequency doubling technology algorithm had both high sensitivity and high specificity in detecting glaucomatous visual field defects, allowing for bilateral screening in less than 5 minutes. (C) 2000 by Elsevier Science Inc. All rights reserved.