Sita-standard and short-wavelength automated perimetry in the early diagnosis of glaucoma

purpose: To compare the Swedish Interactive Threshold Algorithm (SITA-standard) and short-wavelength automated perimetry (SWAP) for detecting early glaucomatous functional abnormalities in a population at risk for glaucoma. Methods: At the Glaucoma Center of the University Eye Clinic, Pavia, the authors studied 50 patients (99 eyes) with intraocular pressure (10P) normalized (IOP < 21 mmHg) by topical therapy. The patients were periodically submitted to automated perimetry with 24-2 pattern and SITA-standard and SWAP strategies of the Humphrey Field Analyzer 750. Each visual field was classified as normal or pathological on the basis of clinical criteria taken from the 1998 guidelines of the European Glaucoma Society. The agreement between the two algorithms in visual field testing was evaluated by kappa statistics and then McNemar's test. Results: Of the 99 eyes studied, 37 showed a pathological SITA test and 23 a pathological SWAP test. In 21 cases, the visual field was abnormal with SITA only, and in seven cases with SWAP only. In 16 cases, early defects were identified by both SITA and SWAP. The agreement between the two strategies was statistically poor (kappa = 0.35). The average test duration was 11.57 +/- 3.02 minutes for SWAP and 5.16 +/- 1.02 minutes for SITA-standard, the difference between the two kinds of test being statistically significant (p < 0.001). Conclusions: Automated perimetry seems to be able to document early glaucomatous abnormalities in many cases. Compared to SWAP, SITA takes less time, is less tiring for the patient, and achieves the same, if not better, quality and accuracy.