[Indications for stimulus 3 and 5 in automatic perimetry. Preliminary results]

Goldmann stimulus size 3 and 5 were studied with automated perimetry in glaucoma patients to help develop specific guidelines for their use.

We examined 49 eyes of 49 glaucoma patients with both stimulus sizes 3 and 5 with Program G1 (all phases) of the Octopus 500 Perimeter. Fields were preformed sequentially, in random order, at the same sitting.

The means of the indices for stimulus size 3 (+/- = standard deviation) were: Mean sensitivity 18.8 +/- 4.7 dB; loss variance 45.0 +/- 42.0 dB2; short-term fluctuation 2.1 +/- 0.45 dB. With stimulus size 5, mean sensitivity increased (Wilcoxon: p < 0.0005) by 8.1 +/- 1.7 dB, and short-term fluctuation decreased (Wilcoxon: p < 0.0005) by 0.3 +/- 0.6 dB. Scotomas measured with stimulus size 5 were shallower than with stimulus size 3, i.e., the pattern of visual field defects was better represented by stimulus size 3 in 13 eyes. Stimulus size 5 was preferred in 14 eyes because more information was available in the area of absolute scotomas. In 6 eyes, deep scotomas within 4 degrees of fixation were seriously underestimated with the larger stimulus.

Stimulus size 5 should be used if more than 10% of test locations have absolute scotomas or the mean sensitivity falls below 15 dB with stimulus size 3. Complementary central fields with stimulus size 3 fields should be used when evaluation of the central field shows relative scotomas with either stimulus.