Purpose:
To identify the incidence of visual field test locations with defects which were spatially similar in fellow eyes of glaucoma patients.
Methods:
Humphrey 24–2 and 30–2 visual fields from both eyes of 314 patients with open–angle glaucoma were graded by the Advanced Glaucoma Intervention Study (AGIS) scoring system, retrospectively. Visual field examinations of fellow eyes were obtained within six months of each other and had AGIS reliability scores of two or better. The foveal location and the locations just above and below the blind spot were not analyzed. The locations of defects common to both eyes were recorded. For each series of comparisons of fellow eyes with each other and for each patient, the average number of locations with spatially similar defects was calculated.
Results:
Six–hundred twenty eight fellow eyes of 314 patients with 2805 visual field examinations were analyzed. The mean number of examinations (±SD) was 4.5 (±3.0) (range 1 to 20). The mean difference in days (±SD) between examination dates of fellow eyes was 2.3 (±61.5). Forty nine percent of fellow eyes had at least one visual field defect location in common. The mean number (±SD) of defects in the same location in fellow eyes was 15.3 (±14.2) per patient (range 1 to 51). The distribution of defects across the 53 visual field locations was fairly uniform with a mean of 1.9% (±0.4%) per location (range 1.2% to 2.8%). Visual field locations with the highest proportion of defects common to fellow eyes were found in the superior arcuate area, while locations with the lowest proportion of common defects were in the inferior nasal step area.
Conclusions:
About half of fellow eyes had patterns of glaucomatous visual field loss which were similar. The similarity of patterns suggests that it may be clinically useful, when a defect in one eye is found, to spend proportionately more time testing similar locations in the contralteral eye.