Test-retest variability of blue-on-yellow perimetry is greater than white-on-white perimetry in normal subjects

PURPOSE: To compare long-term fluctuation of blue-on yellow automated perimetry with white-on-white automated perimetry in normal subjects. METHODS: White-on-white and blue-on-yellow automated perimetry were performed on a Humphrey Visual Field Analyzer and an Octopus perimeter, both modified for blue-on-yellow perimetry. The study sample consisted of 31 eyes of 31 normal subjects for the Humphrey perimeter and 33 eyes of 33 normal subjects for the Octopus perimeter. After one practice session, each subject completed four testing sessions over a period of 2 to 8 weeks, each separated by at least 1 day. Each testing session consisted of both white-on-white and blue-on-yellow perimetry performed on one eye; the order of the rests was alternated for successive sessions. Long-term fluctuation (expressed as statistical variance) was calculated for each test location. Intersubject variability (expressed as statistical variance) across all subjects was determined for each test location. RESULTS: On the Humphrey perimeter, the long term fluctuation for blue-on-yellow perimetry (4.07 +/- 3.07 dB(2)) was significantly greater than that for white-on-white perimetry (1.97 +/- 0.99 dB(2); P <.001). Long-term fluctuation increased as a function of eccentricity for both blue-on-yellow and white-on-white perimetry. Short term fluctuation was significantly greater for blue-on-yellow (0.46 +/- 0.25 dB) than that for white-on-white perimetry (0.29 +/- 0.19 dB; P <.02). Finally, the intersubject variability was significantly greater in blue-on yellow (13.2 +/- 2.8 dB(2)) than it was in white-on-white perimetry (4.25 +/- 1.13 dB(2); P <.001). Similar results were found with the Octopus perimeter. CONCLUSIONS: Long-term fluctuation and short-term fluctuation of blue-on-yellow perimetry are greater than those of white-on-white perimetry in normal subjects. The increased long-term fluctuation requires appropriate statistical approaches when evaluating serial change of blue-on-yellow perimetry. (C) 1998 by Elsevier Science Inc. All rights reserved.