Reproducibility of the data determined by scanning laser polarimetry

Junghardt, Armin; Schmid, Martin; Schipper, Isaak; Wildberger, Hannes; Seifert, Burkhardt

doi:10.1007/bf00185296

Cited by 20 publications

(11 citation statements)

References 14 publications

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“…Several investigations have reported that the reproducibility of measurements made by the NFA is generally better than that made by OCT [20, 21, 22, 23, 24, 25, 26, 27]. The results of this study are almost consistent with those of previous reports.…”

Section: Discussionsupporting

confidence: 83%

Comparison of the Effectiveness of Scanning Laser Polarimetry and Optical Coherence Tomography for Estimating Optic Nerve Fibre Layer Thickness in Patients with Glaucoma

Furuichi¹,

Kashiwagi²,

Furuichi³

et al. 2002

Ophthalmologica

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Purpose: The effectiveness of scanning laser polarimetry (by the nerve fibre analyser, NFA) and of optical coherence tomography (OCT) in estimating nerve fibre layer thickness (NFLT) and the correlations between NFLT and cup-to-disc (C/D) ratio or values of mean deviation (MD) from static visual field tests were compared using patients with glaucoma. Materials and Methods: Twenty-four eyes from 24 glaucoma patients were enrolled. The NFLT was measured along a circle with a diameter 1.5 times that of the optic disc around the optic disc. The averaged estimated NFLT of the circle or of each quadrantal NFLT (nasal, temporal, superior, inferior) was compared. Results: The co-variant indexes measured by the NFA were significantly smaller than those measured by OCT in both the averaged NFLT (p = 0.0002) and in each quadrantal NFLT (p < 0.05). The C/D ratio was significantly correlated with the averaged NFLT when measured by OCT (r = 0.425, p = 0.038), but not by the NFA (r = 0.179, p = 0.407). However, when measured by OCT, these values showed a significant correlation (r = 0.425, p = 0.039). Although both the OCT and NFA data showed significant correlations between NFLT and the MD (p = 0.0002 and p = 0.038, respectively), the OCT data showed a stronger correlation than did the NFA data (r = 0.677 and r = 0.422, respectively). The correlation between the averaged NFLTs obtained by NFA and OCT was not significant (r = 0.289, p = 0.172). Conclusion: OCT is thought to have an equal or better effectiveness for estimating NFLT, in spite of a lower reproducibility than that of the NFA.

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Section: Discussionsupporting

confidence: 83%

Comparison of the Effectiveness of Scanning Laser Polarimetry and Optical Coherence Tomography for Estimating Optic Nerve Fibre Layer Thickness in Patients with Glaucoma

Furuichi¹,

Kashiwagi²,

Furuichi³

et al. 2002

Ophthalmologica

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“…Sessions took place at a 1-week interval and were performed by the same operator. Previous papers evaluated reproducibility of SLP measurements with older versions of the Nerve Fiber Analyzer (I, II, and GDx with fixed corneal compensation) [17,18,19,20,21,22,23,24,25,26]. Overall results were fair to good.…”

Section: Discussionmentioning

confidence: 90%

“…Another feature that any reliable diagnostic instrument must possess is high reproducibility of measurements, mainly for disease follow-up. Reproducibility of measurements with older versions of GDx have previously been assessed in detail [17,18,19,20,21,22,23,24,25,26]. More recently a few papers evaluated GDx-VCC interdevice [27], intraoperator [28] or intraobserver reproducibility [29].…”

Section: Introductionmentioning

confidence: 99%

Intersession Reproducibility of Retinal Nerve Fiber Layer Thickness Measurements by GDx-VCC in Healthy and Glaucomatous Eyes

et al. 2006

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Background: To assess intersession reproducibility of retinal nerve fiber layer (RNFL) thickness measurements on scanning laser polarimetry with variable corneal compensation (GDx-VCC) in a sample of healthy subjects and glaucoma patients. Methods: One eye each from 29 healthy and 29 glaucomatous subjects was selected and underwent RNFL scanning by the same operator at baseline and 1 week later. Glaucoma diagnosis relied on the presence of a reproducible defect on automated perimetry. GDx-VCC parameters considered were those available on page 1 of the printout [TSNIT average and standard deviation (SD), superior and inferior average (SA, IA), Nerve Fiber Indicator]. Reproducibility was assessed by calculating coefficient of variation and intraclass correlation coefficient separately for the two groups and for each parameter. The percentage of eyes with an intersession difference in thickness parameters of more than 5% was also calculated. Results: Coefficient of variation was <6% for TSNIT average, SA and IA in both groups. Corresponding values for TSNIT SD in healthy subjects and in glaucoma patients were 13.7 and 11.4%, respectively, whereas for Nerve Fiber Indicator they were 82.9 and 13.3%. Intraclass correlation coefficient ranged from 0.794 to 0.907 in healthy subjects and from 0.924 to 0.972 in glaucoma patients. In healthy subjects, TSNIT average, SA and IA intersession difference was 5% or less in 55–69% of eyes, whereas the value for TSNIT SD was 34.5%. Corresponding values in glaucomatous eyes ranged from 69 to 79.3% for TSNIT average, SA and IA and was 37.9% for TSNIT SD. Conclusions: Intersession reproducibility of RNFL thickness measurements on GDx-VCC is high, both in healthy and in glaucomatous eyes. In a few cases, however, intersession variation may be larger than 10%. Caution is necessary while interpreting these changes during follow-up, in order to separate physiological variability from real RNFL thickness variations.

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“…The NFA used for our study has already shown good reproducibility [4, 9, 10], above all in its second version [6]. Nevertheless, we have to consider that there is the risk, due to the variable interindividual number of fibers at birth, to underestimate the RNFL thickness of subjects with a thick baseline value, as well as to overestimate the thinning of RNFL in subjects with a thin baseline value of RNFL.…”

Section: Discussionmentioning

confidence: 99%

“…Its specificity has been evaluated good even if certain interobserver variability has been described. Some technical changes to the second version of this machine have improved the reproducibility of its measurements [6, 9, 10]. …”

Section: Introductionmentioning

confidence: 99%

Visual Field Defects and Normal Nerve Fiber Layer: May They Coexist in Primary Open-Angle Glaucoma?

Natale¹,

Marraffa²,

Morbio³

et al. 2000

Ophthalmologica

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The retinal nerve fiber layer (RNFL) is the anatomical structure most sensitive to glaucoma injury. Before a functional loss such as a visual field defect is displayed, a large number of nerve fibers can be damaged. However, there are glaucoma patients in which an apparently normal RNFL coexists with evident visual field defects. A total of 54 eyes affected with primary open-angle glaucoma were studied. Visual field was examined with the Humphrey Field Analyzer (Zeiss) using program 30-2. The Nerve Fiber Analyzer II (Laser Diagnostic Technologies) was used to study the RNFL of these patients. Mean deviation of the visual field ranged from 6 to 31 dB in all eyes that were examined. The average thickness of the RNFL ranged from 20 to 90 μm. According to our previous experience 75 μm was fixed as the cutoff between normal and pathological values of RNFL thickness. We identified 5 eyes with a RNFL thickness over 75 μm and a visual field with a mean deviation over 6 dB; 9% of the studied eyes were found to have a visual field defect with no changes in RNFL. We conclude that not all subjects have the same number of fibers at birth and that it is therefore possible to underestimate the RNFL changes. Our study illustrates that the concept of normal and altered has to be considered as a relative one for all the aspects characterizing the glaucomatous disease.

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Reproducibility of the data determined by scanning laser polarimetry

Abstract: The instrument is clinically useful only if used by the same observer. If measurements are performed by different observers the ratios of the measurements must be used. Further development in the apparatus is needed to improve interobserver reproducibility.

Cited by 20 publications

References 14 publications

Comparison of the Effectiveness of Scanning Laser Polarimetry and Optical Coherence Tomography for Estimating Optic Nerve Fibre Layer Thickness in Patients with Glaucoma

Comparison of the Effectiveness of Scanning Laser Polarimetry and Optical Coherence Tomography for Estimating Optic Nerve Fibre Layer Thickness in Patients with Glaucoma

Intersession Reproducibility of Retinal Nerve Fiber Layer Thickness Measurements by GDx-VCC in Healthy and Glaucomatous Eyes

Visual Field Defects and Normal Nerve Fiber Layer: May They Coexist in Primary Open-Angle Glaucoma?

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