Intrasession test-retest variability of microperimetry in age-related macular degeneration

Purpose: To determine the intrasession test-retest variability of microperimetry in participants with age-related macular degeneration (AMD).

Methods: This study consisted of two separate groups of subjects who had not performed microperimetry previously. In group 1, 30 AMD and 14 control participants performed three microperimetry examinations of a selected eye within one session (test 1 and 2, first pair; test 2 and 3, second pair). Follow-up examination at 6 months was available in 20 AMD participants in group 1, who performed two microperimetry examinations. In group 2, 71 AMD participants performed a short practice examination, then two microperimetry examinations of the right eye (test 1 and 2, first pair) and two of the left eye (test 3 and 4, second pair).

Results: There was a significant improvement in average point-wise sensitivity (PWS) between the first pair of examination in both groups (P < 0.001), but not in the subsequent pair (P ≥ 0.774). This improvement was not observed at the follow-up visit in the subset of AMD participants in group 1 (P = 0.433). The PWS coefficient of repeatability (CoR) for the second pair of examinations was ± 4.12 dB and ± 4.37 dB for AMD participants for group 1 and 2 respectively.

Conclusions: A significant increase in sensitivity between the first and second test, but not in the subsequent tests, was found for participants who had not performed microperimetry previously. Intrasession test-retest variability can therefore be minimized by discarding the first examination to avoid the influence of a learning effect.