Combination of Structural Testing (GDx VCC Scanning Laser Polarimetry, Stratus Optical Coherence Tomography [OCT], HRT II Confocal Scanning Laser Ophthalmoscopy) and Functional Testing (Frequency Doubling Technology [FDT] Perimetry) for Detection of Glaucoma in the Diagnostic Innovations in Glaucoma Study (DIGS)

Abstract

Abstract: : Purpose: To assess whether the combination of parameters from structural and functional testing for detection of glaucoma can improve diagnostic accuracy in discriminating between healthy and glaucomatous eyes over either type of testing alone. Methods: 40 normal eyes and 48 glaucomatous eyes of 88 DIGS patients were included. Two definitions of glaucoma were considered. The first, glaucomatous visual field damage, was based on repeatable abnormal standard automated perimetry results (GHT or PSD outside of normal limits). The second was based on detection of glaucoma optic neuropathy from assessment of stereophotographs. Subjects had FDT N–30 testing and GDx VCC, Stratus OCT, and HRT II imaging completed within a 6–month interval. For GDx VCC, OCT, and HRT II parameters, the manufacturer's suggested cutoff or values outside normal limits (ONL) of the internal normative database was considered "glaucoma". For FDT, PSD at p < 1% was considered "glaucoma". Sensitivities and specificities were calculated for each parameter. Sensitivities and specificities were then calculated for the combination condition in which "glaucoma" was defined if either FDT or the structural parameter met the abnormal criteria. Results: Sensitivities and specificities for detecting glaucomatous visual field damage using GDx (NFI > 50), OCT inferior average, HRT Moorfields Regression Classification, and FDT PSD were 47.9% and 100%, 60.4% and 100%, 62.5% and 97.5%, 43.8% and 100%, respectively. Combining FDT with each of the structural parameters resulted in an increase in sensitivity with preservation of specificity. Combining FDT with GDx VCC, OCT, and HRT resulted in sensitivities of 68.8%, 75%, and 77.1%, respectively, while specificities remained high at 100%, 100%, and 97.5%, respectively. Conclusions: Combination of parameters from structural tests with parameters from FDT improves sensitivity for detection of glaucoma visual field damage.

Keywords: optic disc • imaging/image analysis: clinical • visual fields