Abstract
Purpose: :
To determine the ability of frequency doubling technology (FDT) and scanning laser polarimetry with variable corneal compensation (GDx-VCC) to detect glaucoma when used individually and in combination.
Methods: :
All participants were tested with the FDT C-20-5 screening protocol and the GDx-VCC. FDT was considered abnormal if at least one of the 17 visual field locations showed reduced sensitivity on both the initial and repeat tests. A GDx-VCC was defined as abnormal if the nerve fiber index (NFI) was in the 51-100 range.
Results: :
For detecting glaucoma irrespective of severity, individual sensitivities, specificities and AUCs were 84%, 82% and 0.83 for FDT, and 50%, 98%, and 0.74 for GDx, respectively. Sensitivities of FDT and GDx were 71% and 18% for detecting mild glaucoma, 94% and 81% for moderate glaucoma, and 100% and 78% for severe glaucoma, respectively. After applying a linear predictor model using a fitting and validation set, the overall sensitivity of FDTcould be increased by 13% in the validation set with a loss in specificity of about 5%. GDx sensitivity could also be increased by 42% in the fitting set and 60% in the validation while preserving the specificities.
Conclusions: :
Combining FDT C-20-5 screening protocol and GDx-VCC TSNIT can improve the specificity of glaucoma detection in comparison with FDT used alone. If specificity of 80-85% is desired, then FDT alone is adequate. Although the present study was performed in a hospital setting, this combination may be useful in community-based glaucoma screening owing ease of transportability these devices, test speed and ease of administration and interpretation.
Keywords: clinical (human) or epidemiologic studies: systems/equipment/techniques