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Multicenter Study
. 2007 Feb;143(2):272-9.
doi: 10.1016/j.ajo.2006.09.049. Epub 2006 Oct 25.

Scanning laser polarimetry with variable and enhanced corneal compensation in normal and glaucomatous eyes

Mitra Sehi  1 , Delia C Guaqueta, William J Feuer, David S Greenfield; Advanced Imaging in Glaucoma Study Group
Affiliations
Multicenter Study

Scanning laser polarimetry with variable and enhanced corneal compensation in normal and glaucomatous eyes

Mitra Sehi et al. Am J Ophthalmol. 2007 Feb.

Abstract

Purpose: To investigate whether correction for atypical birefringence pattern (ABP) using scanning laser polarimetry with enhanced corneal compensation (SLP-ECC) reduces the severity of ABP compared with variable corneal compensation (SLP-VCC) and improves the correlation with visual function.

Design: Prospective observational study.

Methods: Normal and glaucomatous eyes enrolled from four clinical sites underwent complete examination, automated perimetry, SLP-ECC, and SLP-VCC. Eyes were characterized in three groups based upon the typical scan score (TSS): normal birefringence pattern (NBP) was defined as TSS > or = 80, mild ABP as TSS 61 to 79, and moderate-severe ABP as TSS < or = 60. For each of four SLP parameters, the area under the ROC curve (AUROC) was calculated to compare the ability of SLP-ECC and SLP-VCC to discriminate between normal and glaucomatous eyes.

Results: Eighty-four normal volunteers and 45 glaucoma patients were enrolled. Mean TSS was significantly (P < .001) greater using SLP-ECC (98.0 +/- 6.6) compared with SLP-VCC (83.4 +/- 22.5). The frequency of moderate-severe ABP images was significantly (P < .001, McNemar test) higher using SLP-VCC (18 of 129, 14%) compared with SLP-ECC (one of 129, 0.8%). Two SLP-ECC parameters (temporal superior nasal inferior temporal [TSNIT] average and inferior average) had significantly (P = .01, P < .001) higher correlation (r = .45, r = .50, respectively) with MD compared with SLP-VCC (r = .34, r = .37). Among eyes with moderate-severe ABP (n = 18), inferior average obtained using SLP-ECC had significantly (P = .03) greater AUROC (0.91 +/- 0.07) compared with SLP-VCC (0.78 +/- 0.11).

Conclusions: SLP-ECC significantly reduces the frequency and severity of ABP compared with SLP-VCC and improves the correlation between RNFL measures and visual function.

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Figures

Figure 1
Figure 1
Atypical birefringence pattern. Optic nerve photograph of a glaucomatous right eye (top left) and corresponding visual field defect using standard automated perimetry (top right). The bottom left image illustrates the variable corneal compensation scan with atypical birefringence pattern characterized by spoke-like areas of high retardation (typical scan score = 17) particularly evident in the nasal and temporal regions. The bottom right image illustrates the enhanced corneal compensation scan demonstrating superior retinal nerve fiber layer atrophy (typical scan score = 94).
Figure 2
Figure 2
Discriminating power of inferior average thickness using enhanced corneal compensation compared with variable corneal compensation in normal and glaucomatous eyes. Receiver operator characteristic (ROC) curve for inferior average thickness illustrates a significantly (p=0.03) increased area under the ROC curve using enhanced corneal compensation (0.92±0.07, solid line) as compared to VCC (0.76 ± 0.12, dotted line) in eyes with moderate to severe atypical birefringence pattern.
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References

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