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Detecting glaucoma with frequency-doubling technology perimetry: a comparison between N-30 and C-20 screening
Paolo Fogagnolo1, Fabio Mazzolani, Luca Rossetti
1Eye Clinic, Department of Medicine, Surgery, and Odontoiatry, San Paolo Hospital, University of Milan, Milan, Italy. fogagnolopaolo@libero.it
Journal of Glaucoma
|November 9, 2005
Summary
Frequency-doubling technology (FDT) perimetry screening programs N-30 and C-20 show similar glaucoma detection rates for established cases. However, both FDT screening strategies are less effective for early glaucoma with nasal step defects.
Area of Science:
- Ophthalmology
- Medical Technology
- Diagnostic Imaging
Background:
- Glaucoma diagnosis relies on visual field testing.
- Frequency-doubling technology (FDT) perimetry is a visual field screening tool.
- Evaluating FDT screening programs (N-30 and C-20) for glaucoma detection is crucial.
Purpose of the Study:
- To assess the efficacy of FDT perimetry screening programs (N-30 and C-20) in identifying glaucoma.
- To compare the diagnostic capabilities of N-30 and C-20 FDT screening programs.
Main Methods:
- Eighty eyes from 80 patients (40 glaucoma, 40 controls) were studied.
- Standard automated perimetry (SAP) served as the gold standard.
- Patients underwent SAP, N-30 and C-20 FDT screening, and FDT N-30 full-threshold tests.
Main Results:
- Both N-30 and C-20 FDT screening programs achieved 87.5% sensitivity and 90-95% specificity using P < 5% criteria.
- Sensitivity decreased to 75% for nasal step defects with both screening programs.
- FDT N-30 full-threshold testing detected all initial defects.
Conclusions:
- N-30 and C-20 FDT screening programs demonstrate comparable performance in detecting established glaucoma.
- Diagnostic accuracy of FDT screening decreases for glaucoma with nasal step defects.
- FDT full-threshold testing is superior for detecting early glaucomatous defects.