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M. Sehi, D.C. Guaqueta, W.J. Feuer, D.S. Greenfield, Advanced Imaging in Glaucoma Study Group; An Enhancement Module to Improve the Atypical Birefringence Pattern Using Scanning Laser Polarimetry With Variable Corneal Compensation . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3342.
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© ARVO (1962-2015); The Authors (2016-present)
Atypical birefringence pattern (ABP) has been reported in a subset of patients using scanning laser polarimetry (SLP). The purpose of this study was to examine the hypothesis that correction for ABP using the enhanced corneal compensation module (ECC) reduces the frequency and severity of ABP compared to SLP with variable corneal compensation (VCC) and improves the correlation between the SLP parameters and visual function using standard automated perimetry (SAP).
Forty–five perimetric glaucoma (PG) patients (age 62.4±8.7 years) and 85 normal (N) volunteers (age 53.2±10.0 years) were included from four clinical sites. One randomly selected eye was scanned 3 times using VCC and ECC on the same day by the same examiner. Reliable SAP examinations were included. Abnormal SAP was defined as glaucoma hemifield test outside normal limits and pattern standard deviation (PSD) of p<5%. Typical scan score (TSS) of 60 or lower was determined as a measure of ABP. Pearson correlation coefficients were calculated and compared using test of homogeneity among paired correlation coefficients.
Mean TSS significantly (p<0.001) increased using ECC (98.1±6.6) compared to VCC (83.5±22.5) across the sample. The frequency of ABP images was significantly (p<0.001, McNemar test) higher using VCC (18 of 130, 13.8%) compared to ECC (1 of 130, 0.8%). Three ECC parameters (average RNFL, superior RNFL and inferior RNFL) had significantly (p<0.007) higher correlation (r=0.45, r=0.41, r=0.48 respectively) with mean deviation (MD) compared to VCC (r=0.33, r=0.38, r=0.33). Two ECC parameters (average RNFL and inferior RNFL) had significantly (p<0.02) higher correlation (r= –0.54, r= –0.55 respectively) with PSD compared to VCC (r= –0.47, r= –0.45).
ECC significantly reduced the frequency and severity of ABP compared to VCC. Correction for atypia using the ECC module improved the correlation between RNFL thickness measures and visual function in this population.
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