Clinical experiences with the "Swedish interactive threshold algorithm" (SITA)

Abstract

The "Swedish Interactive Threshold Algorithm" (SITA) is a new technique minimizing test time without reduction of data quality. In this retrospective study we compared visual fields assessed with the conventional full-threshold technique with those by SITA and analyzed qualitative and quantitative differences and the test time reduction of SITA. 113 eyes with different glaucomatous field damage of 66 patients aged from 22 to 89 years were included. The patients underwent perimetry with each strategy within four months. Exclusion criteria were eyes with progressing glaucomatous damage and high rate of false-positive results or artifacts by corrective glasses. The qualitative differences of the analysis were small: full threshold demonstrated more relative scotomas in eyes with normal SITA readings, whereas scotomas assessed with SITA were often pronounced to absolute scotomas. Average time reduction by SITA was 40% and depended on the severity of glaucomatous stage. No reduction was found for advanced glaucoma, whereas normal fields using SITA were performed in half of the time of full threshold strategy. Differences of SITA to conventional full threshold testing may be related to fatigue effects of full threshold strategy due to longer test time. The reduction of test time enables more motivation for more frequent visual field examinations and thus a better detection of early glaucoma or progressing visual field damage.