Enhanced Imaging Algorithm for Scanning Laser Polarimetry with Variable Corneal Compensation

Reus, Nicolaas J.; Zhou, Qienyuan; Lemij, Hans G

doi:10.1167/iovs.05-0067

Cited by 81 publications

(95 citation statements)

References 20 publications

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“…We have recently demonstrated how a control cohort with no suspicious findings of glaucoma can affect the diagnostic ability of SDOCT parameters in glaucoma compared with a control cohort which is likely to be misinterpreted as glaucoma. 16 Due to the same reason, AUCs of RNFL parameters reported in our study are also lower compared with the studies that have reported the same with SDOCT 7,10,29 and GDx ECC 5,12,13,30 separately.…”

Section: Discussioncontrasting

confidence: 46%

“…The general principles of SLP and the algorithm used for ECC have been described in detail previously. 3,5,12 The parameters generated on the printout and used in this study were temporal average (temporal 50 degree), superior average (superior 120 degree), nasal average (nasal 70 degree), inferior average (inferior 120 degree), TSNIT (temporal superior nasal inferior and temporal) average (over 360 degree), TSNIT SD, and nerve fiber indicator (NFI). TSNIT SD represents the SD of the values contained in the calculation circle.…”

Section: Methodsmentioning

confidence: 99%

“…The amount of birefringence bias is then mathematically removed point by point from the total 1 VST Glaucoma Center, L V Prasad Eye Institute, Hyderabad, India 2 Center for Clinical Epidemiology and Biostatistics, L V Prasad Eye Institute, Hyderabad, India birefringence pattern of the image to improve the signal and obtain a retardation pattern of the RNFL with the least noise. [4][5][6] Though numerous studies have reported good diagnostic ability of both SDOCT [7][8][9][10][11] and GDx ECC 12,13 in glaucoma, there is limited literature on the head-to-head comparison of these imaging techniques in the same population. 14,15 Also, most of these studies have employed a case-control design including glaucoma patients (cases), defined based on the presence of repeatable characteristic glaucomatous visual field (VF) defects; and normal subjects (controls), usually recruited from the general population and having normal intraocular pressures (IOPs), healthy appearance of the optic nerve and normal VFs.…”

Section: Introductionmentioning

confidence: 99%

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Retinal nerve fiber layer evaluation of spectral domain optical coherence tomograph and scanning laser polarimeter to diagnose glaucoma

Rao

Yadav

Addepalli

et al. 2014

Eye

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Purpose To compare the abilities of retinal nerve fiber layer (RNFL) parameters of spectral domain optical coherence tomograph (SDOCT) and scanning laser polarimeter (GDx enhanced corneal compensation; ECC) in detecting glaucoma. Methods In a cross-sectional study, 215 eyes of 165 subjects (106 eyes of 79 glaucoma patients and 109 eyes of 86 controls) referred by general ophthalmologists for glaucoma evaluation underwent RNFL imaging with SDOCT and GDx ECC. Ability of RNFL parameters of SDOCT to discriminate glaucoma eyes from control eyes was compared with that of GDx ECC using area under operating characteristic curves (AUCs), sensitivities at fixed specificities, and likelihood ratios (LRs). Results AUC of the average RNFL thickness of SDOCT to differentiate glaucoma from control eyes (0.868) was comparable (P ¼ 0.32) to that of GDx ECC (0.855). Sensitivity at 95% specificity was 63.2% for average RNFL thickness of SDOCT and 48.1% for the average RNFL measurement of GDx ECC. LRs of outside normal limits category of SDOCT parameters ranged between 5.6 and 7.7 while the same of GDx ECC parameters ranged between 3.1 and 3.7. LRs of within normal limits category of SDOCT parameters ranged between 0.18 and 0.24 while the same of GDx ECC parameters ranged between 0.20 and 0.32. Conclusion Though AUCs and sensitivities at fixed specificities were comparable between the RNFL parameters of SDOCT and GDx ECC in diagnosing glaucoma, LRs indicated that the RNFL parameters of SDOCT were better in 'ruling in' glaucoma.

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Section: Discussioncontrasting

confidence: 46%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Retinal nerve fiber layer evaluation of spectral domain optical coherence tomograph and scanning laser polarimeter to diagnose glaucoma

Rao

Yadav

Addepalli

et al. 2014

Eye

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“…The ECC protocol introduces a predetermined birefringence bias to shift the measurement of the total retardation to a higher value region to remove noise and reduce atypical patterns. The amount of birefringence bias is then mathematically removed point by point from the total birefringence pattern of the image, to improve the signal and obtain a retardation pattern of the RNFL with the least noise (atypia) (Toth & Hollo 2005;Reus et al 2006;Sehi et al 2006). ABP in SLP scans is quantified by a support vector machine score called typical scan score (TSS) (Bagga et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Atypical birefringence pattern and the diagnostic ability of scanning laser polarimetry with enhanced corneal compensation in glaucoma

Rao

Yadav

Begum

et al. 2014

Acta Ophthalmologica

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ABSTRACT.Purpose: To evaluate the effect of typical scan score (TSS), when within the acceptable limits, on the diagnostic performance of retinal nerve fibre layer (RNFL) parameters with the enhanced corneal compensation (ECC) protocol of scanning laser polarimetry (SLP) in glaucoma. Methods: In a cross-sectional study, 203 eyes of 160 glaucoma patients and 140 eyes of 104 control subjects underwent RNFL imaging with the ECC protocol of SLP. TSS was used to quantify atypical birefringence pattern (ABP) images. Influence of TSS on the diagnostic ability of SLP parameters was evaluated by receiver operating characteristic (ROC) regression models after adjusting for the effect of disease severity [based on mean deviation (MD)] on standard automated perimetry). Results: Diagnostic abilities of all RNFL parameters of SLP increased when the TSS values were higher. This effect was statistically significant for TSNIT (coefficient: 0.08, p < 0.001) and inferior average parameters (coefficient: 0.06, p = 0.002) but not for nerve fibre indicator (NFI, coefficient: 0.03, p = 0.21). In early glaucoma (MD of À5 dB), predicted area under ROC curve (AUC) for TSNIT average parameter improved from 0.642 at a TSS of 90 to 0.845 at a TSS of 100. In advanced glaucoma (MD of À15 dB), AUC for TSNIT average improved from 0.832 at a TSS of 90 to 0.947 at 100. Conclusion: Diagnostic performances of TSNIT and inferior average RNFL parameters with ECC protocol of SLP were significantly influenced by TSS even when the TSS values were within the acceptable limits. Diagnostic ability of NFI was unaffected by TSS values.

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“…9 An analysis of the contribution of backscattered light from various depths to the total retardation map using spectral-domain OCT found that atypical retardation patterns in SLT are associated with deep penetration of the probing light beam into the strongly birefringent sclera. 12 To improve the accuracy, first the already-mentioned VCC, 13 then the software-based ECC 14 were introduced. It appears that GDx ECC performs better than VCC in the detection of glaucoma in early stages of disease.…”

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confidence: 99%

Imaging Technologies for the Diagnosis of Glaucoma

Bochmann¹,

Azuara‐Blanco²

2009

European Ophthalmic Review

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In this article we describe recent advances in imaging technologies that quantify the topography of the optic nerve head and retinal nerve fibre layer and their role in diagnosing glaucoma. These technologies include optical coherence tomography (OCT), scanning laser polarimetry (SLP, GDx) and confocal scanning laser ophthalmoscopy (CSLO, HRT). A review of recently published literature was carried out.The diagnostic performance of the different imaging devices is comparable and appears to be acceptable for the diagnosis of manifest glaucoma. The benefits of recent technological improvements need to be fully assessed. At the moment it is not clear which of the currently used imaging technologies is the most useful for diagnosis and management of glaucoma. KeywordsOptical coherence tomography, scanning laser polarimetrey, confocal scanning laser ophthalmoscopy ) and optical coherence tomography (OCT) (see Figure 1). They can be used to detect early structural damage by focusing on glaucoma-relevant structures of the ONH and surrounding tissues and using a normative database to determine the probability of glaucoma. Imaging of the ONH and the RNFL for detecting glaucoma progression is another important aspect of glaucoma management. However, in this review we will focus only on the role of imaging technologies in the diagnosis of glaucoma.We will provide a brief description of the recent advances, and review the current literature on the diagnostic performance for glaucoma of these imaging devices. Scanning Laser PolarimetrySLP is designed to provide objective assessment of the RNFL thickness with potential use for diagnosis and follow-up. SLP is based on the principle that polarised light passing through the birefringence RNFL undergoes a detectable phase shift, which is linearly related to RNFL thickness. 7 The result is a 2D map of retardation around the optic disc. The software provides a discriminating classifier of glaucoma/normality named nerve fibre indicator (NFI), which is fully automated. To detect change over time, regression analysis can be performed.The first GDx nerve fibre analyser contained a fixed compensating device to compensate for polarisation effects of cornea and lens.

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Enhanced Imaging Algorithm for Scanning Laser Polarimetry with Variable Corneal Compensation

Abstract: RNFL morphology may be better assessed with the presented ECC method than with standard VCC. ECC may be implemented in the current VCC systems by means of a software upgrade. It may enhance the clinical utility of the GDx VCC in glaucoma management.

Cited by 81 publications

References 20 publications

Retinal nerve fiber layer evaluation of spectral domain optical coherence tomograph and scanning laser polarimeter to diagnose glaucoma

Retinal nerve fiber layer evaluation of spectral domain optical coherence tomograph and scanning laser polarimeter to diagnose glaucoma

Atypical birefringence pattern and the diagnostic ability of scanning laser polarimetry with enhanced corneal compensation in glaucoma

Imaging Technologies for the Diagnosis of Glaucoma

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