Detection of visual-field deterioration by Glaucoma Progression Analysis and Threshold Noiseless Trend programs
- 1Hospital Universitario de Canarias, La Laguna, Spain
- 2Institut Catala de Retina and Hospital de la Esperanza y el Mar, Barcelona, Spain
- 3Leicester Royal Infirmary, Leicester, UK
- 4Raigmore Hospital, Inverness, UK
- 5Grampian University Hospitals NHS Trust, University of Aberdeen, Aberdeen, UK
- Dr A Azuara-Blanco, The Eye Clinic, Aberdeen Royal Infirmary, Aberdeen AB25 2ZN, UK;
- Accepted 25 June 2008
- Published Online First 11 July 2008
Background: To compare the ability of Glaucoma Progression Analysis (GPA) and Threshold Noiseless Trend (TNT) programs to detect visual-field deterioration.
Methods: Patients with open-angle glaucoma followed for a minimum of 2 years and a minimum of seven reliable visual fields were included. Progression was assessed subjectively by four masked glaucoma experts, and compared with GPA and TNT results. Each case was judged to be stable, deteriorated or suspicious of deterioration
Results: A total of 56 eyes of 42 patients were followed with a mean of 7.8 (SD 1.0) tests over an average of 5.5 (1.04) years. Interobserver agreement to detect progression was good (mean kappa = 0.57). Progression was detected in 10–19 eyes by the experts, in six by GPA and in 24 by TNT. Using the consensus expert opinion as the gold standard (four clinicians detected progression), the GPA sensitivity and specificity were 75% and 83%, respectively, while the TNT sensitivity and specificity was 100% and 77%, respectively.
Conclusion: TNT showed greater concordance with the experts than GPA in the detection of visual-field deterioration. GPA showed a high specificity but lower sensitivity, mainly detecting cases of high focality and pronounced mean defect slopes.
Funding: Supported in part by FEDER foundation and Fondo de Investigation Sanitaria (FIS), Instituto Carlos III, Ministerio de Sanidad and Consumo, Spain.
Competing interests: MGR has commercial interest in one of the software packages used in this study, Threshold Noiseless Trend (TNT).