Purpose: To evaluate the new threshold strategies of the Humphrey Field Analyser, SITA Standard and SITA Fast, in normals and glaucoma patients.
Methods: Fifty healthy volunteers and 50 glaucoma patients were tested twice with three algorithms: Full Threshold, SITA Standard and SITA Fast in two sessions. The second test was taken into account to eliminate learning effect. Glaucoma patients were chosen to cover a large range of deficits. Quantitative analysis of global indexes was performed as well as qualitative comparison of visual fields by a trained optometrist.
Results: Compared to Full Threshold, testing time was reduced by 51% in normals and 49% in glaucoma with SITA Standard and by 72% and 69% with SITA Fast, respectively. In glaucoma, mean testing time dropped from 16'01" with Full Threshold to 8'05" with SITA Standard and to 4'55" with SITA Fast. Quantitative comparison showed a high correlation between indexes (MD Full Threshold vs MD SITA Standard: r = 0.98, p < 0.01; PSD Full Threshold vs PSD SITA Standard: r = 0.94, p < 0.01). However SITA Standard and SITA Fast had a tendency to underestimate visual field defects. In glaucomatous subjects, mean MD ameliorated by 1.01 dB with SITA Standard and by 1.71 dB with SITA Fast. Mean PSD ameliorated by 0.04 dB and 0.43 dB, respectively. Qualitative analysis confirmed these last results showing artificial slight or important improvement of visual fields in 21% of the cases with SITA Standard and 30% with SITA Fast, compared to Full Threshold.
Conclusion: SITA Standard and SITA Fast strategies improve dramatically visual field testing time, by 51% and 72% respectively. However, one should be cautious in comparing results obtained with different algorithms, as these new strategies improve the mean defect and, to a lesser extent, the localized defect.