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Discrimination between normal and glaucomatous eyes with the Topographic Scanning System: a preliminary report
Leopoldo Magacho1, Ana M Marcondes, Vital P Costa
1University of Campinas, Campinas, Brazil.
Background And Objective:
To evaluate the ability of the Topographic Scanning System (TopSS; Laser Diagnostic Technologies, San Diego, CA) to differentiate individuals with glaucoma from normal subjects.
Patients And Methods:
The subjects were divided into two groups: primary open-angle glaucoma and normal. All individuals underwent a complete ophthalmic evaluation, a 24-2 full threshold Humphrey visual field evaluation, and a TopSS examination. Cut-off points were selected, receiver operator characteristic (ROC) curves were created, and sensitivity and specificity were calculated for individual TopSS parameters and combinations of variables using multivariate analysis.
Results:
One hundred twelve patients with glaucoma and 88 normal individuals were enrolled in the study. The best TopSS individual parameters were: average disc diameter (sensitivity: 64%, specificity: 89%, area under ROC curve: 0.824), total disc area (sensitivity: 85%, specificity: 66%, area under ROC curve: 0.802), and cup area (sensitivity: 69%, specificity: 85%, area under ROC curve: 0.797). The multivariate analysis resulted in an area under the ROC curve of 0.91 (sensitivity: 90%, specificity: 81%).
Conclusions:
This preliminary report suggests that the use of a multivariate discriminant formula may enhance the ability to differentiate individuals with glaucoma from normal subjects with the TopSS, with high sensitivity and specificity. Further studies investigating a random population are needed to test the validity of this formula.
