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[Perimetry with normal Octopus technique and Weber 'dynamic' technique. Initial results with reference to
M Zulauf1, P Fehlmann, J Flammer
1Universitäts-Augenklinik, Basel.
Unlabelled:
There is ample reason to strive for a shorter test without losing solid and reproducible information on the function of the eye. The purpose of this study was to compare the standard Octopus strategy with the 'dynamic strategy' of Weber in terms of time requirement and reproducibility of results, i.e., short-term as well as long-term fluctuations in glaucoma.
Materials And Methods:
On an Octopus 1-2-3 automated perimeter, 23 experienced glaucoma patients with predominantly local loss completed three test sessions, each consisting of a short training test followed by six visual fields, i.e., the first 'stage' (16 test locations) of program GIX, beginning at random with one strategy, then alternating the strategies.
Results:
The deviation from normal values of the 1104 test locations obtained with the standard and the dynamic strategy (mean +/- SD) was 5.2 +/- 7.5 dB and 4.6 +/- 7.3 dB (P < 0.02), respectively. The short-term fluctuation (given as variance) with the standard and the dynamic strategy averaged 8.3 +/- 5.9 dB2 and 10.2 +/- 5.8 dB2 (p < 0.02), respectively. The long-term fluctuation, i.e., 'test-to-test' variation (given as variance), with the standard and the dynamic strategy was 6.4 +/- 16.5 dB2 and 7.89 +/- 19.2 dB2 (P < 0.22), respectively. The total long-term fluctuation of the index mean defect, MD, averaged 1.8 +/- 2.7 dB2 and 1.3 +/- 1.7 dB2 (P = 0.69), respectively, with the standard and the dynamic strategy. The number or stimuli required with the standard and the dynamic strategy averaged 5.6 +/- 1.4 and 3.0 +/- 1.0 (P < 0.001), respectively.
Conclusions:
The dynamic strategy required 43% fewer stimuli and presented 23% (significantly) higher short-term fluctuation, but long-term fluctuations were similar for both strategies. The two strategies were comparable regarding the respective reproducibility of the results. However, further studies may investigate the sensitivity and the specificity of either strategy to distinguish disease from normal, or, change during a follow-up of a disease, and, may elucidate whether the observed differences between the two strategies are due to the modified step size, or, to the single (versus double) crossing of the threshold.