A new rapid threshold algorithm for short-wavelength automated perimetry.

PURPOSE

To develop and test a short and reliable visual field threshold program for the early detection of glaucomatous visual field loss, by adapting the Swedish interactive test algorithm (SITA) to short-wavelength-automated-perimetry (SWAP).

METHODS

Computer simulations were performed to test the accuracy of several versions of SITA SWAP, and to optimize speed versus reliability. The selected SITA SWAP version was evaluated and compared with the older Full Threshold SWAP and Fastpac SWAP programs in 41 patients with glaucoma and normal subjects.

RESULTS

Average test time was 3.6 minutes for SITA SWAP, 11.8 minutes for Full Threshold SWAP, and 7.7 minutes for Fastpac SWAP, differences were significant at P < 0.0001. Mean threshold reproducibility, calculated as absolute difference between two tests, did not differ significantly between programs and was 2.4 dB for SITA, 2.3 dB for Full Threshold, and 2.4 dB for Fastpac SWAP. Simultaneous comparison showed significant differences in threshold sensitivity, P = 0.023: SITA SWAP showed highest sensitivity, 21.6 dB on average, compared with both Full Threshold SWAP and Fastpac SWAP with a mean sensitivity of 17.3 and 17.8 dB, respectively.

CONCLUSIONS

SITA SWAP was much faster than the older SWAP strategies, and reproducibility did not differ. This implies that SITA SWAP could become a clinically useful method for the detection of early glaucoma. SWAP tests may also be applicable in larger groups of patients because of the increased dynamic range.