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Comparison of glaucomatous visual field defects using standard full threshold and Swedish interactive threshold
Donald L Budenz1, Paul Rhee, William J Feuer
1Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami School of Medicine, 900 NW 17th St, Miami, FL 33136, USA.
Archives of Ophthalmology (Chicago, Ill. : 1960)
|September 7, 2002
Summary
Newer Swedish Interactive Thresholding Algorithm (SITA) fast and standard algorithms measure shallower glaucomatous visual field defects compared to the standard Full Threshold algorithm. However, defect size and severity remain comparable, advising caution when converting measurements between algorithms.
Area of Science:
- Ophthalmology and Visual Science
- Optometry and Vision Science
- Medical Technology and Instrumentation
Background:
- Glaucoma is a progressive optic neuropathy leading to characteristic visual field defects.
- Accurate measurement of defect severity, size, and depth is crucial for monitoring glaucoma progression.
- Humphrey perimeter algorithms, including Full Threshold (FT) and Swedish Interactive Thresholding Algorithm (SITA) standard (SS) and SITA fast (SF), are used for visual field testing.
Purpose of the Study:
- To compare the severity, size, and depth of glaucomatous visual field defects.
- To evaluate differences between the standard Full Threshold (FT) algorithm and the SITA standard (SS) and SITA fast (SF) algorithms on the Humphrey perimeter.
Main Methods:
- Prospective observational case series of 77 glaucoma patients.
- Patients underwent FT, SS, and SF 30-2 white-on-white testing on the same day, repeated over one month.
- Defect severity (mean deviation, pattern standard deviation, AGIS, HAP scores), size (total abnormal points), and depth (sum of threshold values) were analyzed.
Main Results:
- SITA algorithms (SS and SF) showed slightly better mean deviations and Advanced Glaucoma Intervention Study (AGIS) scores compared to FT.
- No significant differences in pattern standard deviations were found between SS/SF and FT, though SS was higher than SF.
- Defect sizes were slightly larger with SS than FT, but not significantly different with SF. Defect depths were significantly shallower with SS and SF compared to FT.
Conclusions:
- Glaucomatous defects are measured as significantly shallower using SITA algorithms (SS, SF) compared to the FT algorithm.
- Defect size and severity measurements are comparable between FT and SITA algorithms.
- Caution is advised when converting threshold values for glaucomatous defects between FT and SITA algorithms due to depth measurement differences.