Sensitivity and Specificity of Swedish Interactive Threshold Algorithm and Standard Full Threshold Perimetry in Primary Open-angle Glaucoma

Abstract Perimetry is one of the mainstays in glaucoma diagnosis and treatment. Various strategies offer different accuracies in glaucoma testing. Our aim was to determine and compare the diagnostic sensitivity and specificity of Swedish Interactive Threshold Algorithm (SITA) Fast and Standard Full Threshold (SFT) strategies of the Humphrey Field Analyzer (HFA) in identifying patients with visual field defect in glaucoma disease. This prospective observational case series study was conducted in a university-based eye hospital. A total of ۳۷ eyes of ۲۰ patients with glaucoma were evaluated using the central ۳۰-۲ program and both the SITA Fast and SFT strategies. Both strategies were performed for each strategy in each session and for four times in a ۲-week period. Data were analyzed using the Student’s t-test, analysis of variance, and chi-square test. The SITA Fast and SFT strategies had similar sensitivity of ۹۳.۳%. The specificity of SITA Fast and SFT strategies was ۵۷.۴% and ۷۱.۴% respectively. The mean duration of SFT tests was ۱۴.۶ minutes, and that of SITA Fast tests was ۵.۴۵ minutes (a statistically significant ۶۲.۵% reduction). In gray scale plots, visual field defect was less deep in SITA Fast than in SFT; however, more points had significant defect (p < ۰.۵% and p < ۱%) in pattern deviation plots in SITA Fast than in SFT; these differences were not clinically significant. In conclusion, the SITA Fast strategy showed higher sensitivity for detection of glaucoma compared to the SFT strategy, yet with reduced specificity; however, the shorter test duration makes it a more acceptable choice in many clinical situations, especially for children, elderly, and those with musculoskeletal diseases.