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D. S. Grewal, M. Sehi, D. S. Greenfield, Advanced Imaging in Glaucoma Study Group; Detecting Glaucomatous Progression Using Scanning Laser Polarimetry With Variable and Enhanced Corneal Compensation. Invest. Ophthalmol. Vis. Sci. 2009;50(13):2251.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the impact of corneal compensation on detection of glaucoma progression using scanning laser polarimetry.
Normal, glaucoma suspect and glaucoma patients with 24 months follow-up meeting eligibility criteria were prospectively enrolled. All subjects underwent complete eye exam, SAP, scanning laser polarimetry with variable and enhanced corneal compensation (GDxVCC and GDxECC). Glaucoma progression (GDx-GPA, Carl Zeiss Meditec) was defined as repeatable change on 2 consecutive scans compared with 2 baseline images using any of 3 strategies: ≥150 contiguous pixels on the progression map (method A),≥4 adjacent segments on the TSNIT graph (method B), or significant change in slope of the summary parameters (method C). Abnormal birefringence pattern (ABP) was defined as a TSS ≤60.
Thirteen normal, 31 suspect, and 29 glaucomatous eyes were included. Progression was identified in 5 eyes using GDxVCC (2 suspect, 3 glaucoma) and 7 eyes using GDxECC (4 suspect, 3 glaucoma). Agreement among progression methods was strongest for method C (kappa=0.7, p<0.001) compared with methods A (kappa=0.3, p=0.03) and B (kappa=-0.04, p=0.7). Mean TSS scores in normal, suspect, and glaucomatous eyes were significantly (p<0.01) higher using GDxECC (97.9±3.8, 98.8± 2.9, 97.8±4.8) compared with VCC (81.8±22.2, 86.8±19.9, 71.8±27.4). Mean TSS values were similar in progressing and non-progressing eyes using VCC (70.7± 29.5, 80.6±23.9, p=0.4) and ECC (99.1±1.5, 98.1±4.0, p=0.5). Eight patients (11%) underwent a change in progression classification (converters) when using GDxECC compared with GDxVCC. Mean GDxVCC TSS scores in converters (78.8± 28.0) and non-converters (80.1± 24.4) were similar (p=0.9). ABP was not associated (r=0.14, p=0.7) with a change in progression classification.
Longitudinal detection of glaucoma progression using scanning laser polarimetry with variable and enhanced corneal compensation is not interchangeable. Differences in progression detection are not explained by atypical birefringence.
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