Effect of glaucomatous damage on repeatability of confocal scanning laser ophthalmoscope, scanning laser polarimetry, and optical coherence tomography.

PURPOSE: To determine and compare the effect of the severity of glaucomatous damage on the repeatability of retinal nerve fiber layer (RNFL) thickness with GDx-VCC (variable corneal compensation) and StratusOCT (optical coherence tomography; both produced by Carl Zeiss Meditec, Inc., Dublin, CA), and optic nerve head (ONH) topography with HRT-II (retinal tomograph; Heidelberg Engineering GmbH, Heidelberg, Germany) and StratusOCT. METHODS: With each of these techniques, two measurements were obtained from 41 eyes of 41 control subjects and 98 glaucomatous eyes (37 patients with early, 29 with moderate, and 32 with severe field loss). To evaluate test-retest variability at each stage, limits of agreement (Bland-Altman plots) and repeatability coefficients (RCs) were obtained from pairs of measurements. Comparisons of within-subject variances were used to compare repeatability of GDx-VCC versus StratusOCT for global RNFL and HRT-II versus StratusOCT for global ONH topography. Effects from age, visual acuity, and lens status were also included in the analysis as covariates. RESULTS: Test-retest variability of RNFL using GDx-VCC and StratusOCT were consistent through all stages of disease severity. Repeatability results of GDx-VCC were better than those of StratusOCT, except in severe cases. Test-retest variability of ONH topography using HRT-II and StratusOCT increased with increasing disease severity for rim area, cup area, and cup-to-disc (C/D) area ratio. In contrast, vertical C/D ratio from HRT-II, and horizontal C/D ratio from StratusOCT showed stable test-retest variability through all stages. Regardless of disease severity, repeatability results of HRT-II were better than those of StratusOCT. CONCLUSIONS: GDx-VCC and HRT-II showed better repeatability than StratusOCT. Although test-retest variability increased with disease severity for rim area, the variability for vertical C/D ratio (HRTII) and global RNFL (GDx-VCC) was stable across disease severity. These parameters, rather than rim area, may be more useful in detection of progression in patients with glaucoma who have more advanced field loss.

Comparison of the Moorfields classification using confocal scanning laser ophthalmoscopy and subjective optic disc classification in detecting glaucoma in blacks and whites.

OBJECTIVE: To compare the diagnostic accuracy of the Moorfields regression classification (MRC) and subjective optic disc evaluation in discriminating early to moderate glaucomatous from nonglaucomatous eyes. DESIGN: Cross-sectional observational study. PARTICIPANTS: Two hundred thirty-three patients with glaucoma and 216 normal subjects were included in the analysis. Racial groups were defined by self-description. METHODS: All subjects underwent confocal scanning laser ophthalmoscopy, stereophotography, and standard perimetry. Glaucoma was defined by visual field defect alone and confirmed with a second visual field test. Stereo photographs were graded as either normal or glaucomatous appearing in a masked fashion by 2 independent graders and adjudicated by a third grader in cases of disagreement. Mean disc area was compared between patients correctly and incorrectly diagnosed with either technique. MAIN OUTCOME MEASURES: Sensitivity and specificity of MRC and subjective evaluation of stereophotographs in the detection of glaucomatous visual field loss. RESULTS: With the MRC, the sensitivity and specificity were higher using the 95% cutoff than using the 99.9% cutoff. Classification based on subjective photo assessment had a greater agreement with the diagnosis of glaucoma than the MRC for blacks (MRC, sensitivity = 62.5%, specificity = 93.2%; Photo, sensitivity = 76.5%, specificity = 91.5%) and whites (MRC, sensitivity = 67.0%, specificity = 92.2%; photo, sensitivity = 78.4%, specificity = 91.9%). Disc area was significantly larger in patients incorrectly diagnosed with the MRC (P = 0.0289). CONCLUSIONS: Subjective optic disc grading by glaucoma specialists outperformed the MRC with the HRT II in both black and white subjects. Both subjective and objective diagnostic methods were associated with similar sensitivity and specificity between racial groups. The MRC was more likely to provide an incorrect diagnosis in subjects with larger optic discs.

Discrimination between glaucomatous and nonglaucomatous eyes using quantitative imaging devices and subjective optic nerve head assessment.

PURPOSE: To compare the diagnostic ability of the confocal scanning laser ophthalmoscope (HRT-II; Heidelberg Engineering, Heidelberg, Germany), scanning laser polarimeter (GDx-VCC; Carl Zeiss Meditec, Inc., Dublin, CA), and optical coherence tomographer (StratusOCT, Carl Zeiss Meditec, Inc.) with subjective assessment of optic nerve head (ONH) stereophotographs in discriminating glaucomatous from nonglaucomatous eyes. METHODS: Data from 79 glaucomatous and 149 normal eyes of 228 subjects were included in the analysis. Three independent graders evaluated ONH stereophotographs. Receiver operating characteristic curves were constructed for each technique and sensitivity was estimated at 80% of specificity. Comparisons of areas under these curves (aROC) and agreement (kappa) were determined between stereophoto grading and best parameter from each technique. RESULTS: Stereophotograph grading had the largest aROC and sensitivity (0.903, 77.22%) in comparison with the best parameter from each technique: HRT-II global cup-to-disc area ratio (0.861, 75.95%); GDx-VCC Nerve Fiber Indicator (NFI; 0.836, 68.35%); and StratusOCT retinal nerve fiber layer (RNFL) thickness (0.844, 69.62%), ONH vertical integrated rim area (VIRA; 0.854, 73.42%), and macular thickness (0.815, 67.09%). The kappa between photograph grading and imaging parameters was 0.71 for StratusOCT-VIRA, 0.57 for HRT-II cup-to-disc area ratio, 0.51 for GDX-VCC NFI, 0.33 for StratusOCT RNFL, and 0.28 for StratusOCT macular thickness. CONCLUSIONS: Similar diagnostic ability was found for all imaging techniques, but none demonstrated superiority to subjective assessment of the ONH. Agreement between disease classification with subjective assessment of ONH and imaging techniques was greater for techniques that evaluate ONH topography than with techniques that evaluate RNFL parameters. A combination of subjective ONH evaluation with RNFL parameters provides additive information, may have clinical impact, and deserves to be considered in the design of future studies comparing objective techniques with subjective evaluation by general eye care providers.