Purpose: To prospectively study the learning effects and measurement variability in frequency-doubling technology perimetry in glaucoma patients who were well practiced in testing with an automated static perimeter.
Patients and methods: Patients with clinically stable chronic open-angle glaucoma (n = 44) who had undergone repeated perimetric testing using a 30-2 full-threshold program with a Humphrey perimeter with reliable results were enrolled in the study. The authors tested each patient using frequency-doubling technology perimetry. After initial examination with the C-20-1 screening program, the N-30 full-threshold program was performed three times at 1- to 3-month intervals.
Results: Perimetric results of the N-30 program improved with repeated testing in both eyes between the first and second visits. The average of mean deviation (MD) of the N-30 program significantly improved by 0.6 dB ( < 0.001) in the right eye and 0.8 dB ( < 0.002) in the left eye between the first and second sessions. The sensitivity in 4 of 19 test points (right eye) and 5 of 19 points (left eye) improved significantly at the second sessions, but not the third session. There were no significant differences in the FDT results between the second and third sessions in both eyes. The standard deviation of the mean MD value for the three sessions ranged from 3.8 to 4.0 dB in both eyes.
Conclusion: Baseline measurements for perimetric follow-up with the N-30 full-threshold program in patients with glaucoma should be repeated at least twice after testing with the C-20-1 screening program.