Scanning Laser Polarimetry to Measure the Nerve Fiber Layer of Normal and Glaucomatous Eyes
TL;DR: Scanning laser polarimetry provides quantitative measurements that correspond to known properties of the retinal nerve fiber layer in normal and glaucomatous eyes.
About: This article is published in American Journal of Ophthalmology.The article was published on 1995-05-01. It has received 476 citations till now. The article focuses on the topics: Scanning laser polarimetry & Glaucoma.
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TL;DR: Nerve fiber layer thickness can be reproducibly measured using OCT; internal is superior to external fixation; each circle diameter tested provides adequate reproducibility.
686 citations
TL;DR: For the early detection of glaucomatous optic nerve damage in ocular hypertensive eyes before the development of visual field loss, the most important variables are neuroretinal rim shape, optic cup size in relation to optic disk size, diffusely or segmentally decreased visibility of the RNFL, occurrence of localized RNFL defects, and presence of disk hemorrhages.
557 citations
TL;DR: The abilities of current commercially available versions of 3 optical imaging techniques: scanning laser polarimetry with variable corneal compensation, confocal scanning laser ophthalmoscopy, and optical coherence tomography to discriminate between healthy eyes and eyes with glaucomatous visual field loss are compared.
Abstract: Objective: To compare the abilities of current commercially available versions of 3 optical imaging techniques: scanning laser polarimetry with variable corneal compensation (GDx VCC), confocal scanning laser ophthalmoscopy (HRT II [Heidelberg Retina Tomograph]), and optical coherence tomography (Stratus OCT) to discriminate between healthy eyes and eyes with glaucomatous visual field loss. Methods: We included 107 patients with glaucomatous visual field loss and 76 healthy subjects of a similar age. All individuals underwent imaging with a GDx VCC, HRT II, and fast retinal nerve fiber layer scan with the Stratus OCT as well as visual field testing within a 6-month period. Receiver operating characteristic curves and sensitivities at fixed specificities (80% and 95%) were calculated for parameters reported as continuous variables. Diagnostic categorization (outside normal limits, borderline, or within normal limits) provided by each instrument after comparison with its respective normative database was also evaluated, and likelihood ratios were reported. Agreement on categorization between methods (weighted ) was assessed. Results: After the exclusion of subjects with unacceptable images, the final study sample included 141 eyes of 141 subjects (75 with glaucoma and 66 healthy control subjects). Mean±SD mean deviation of the visual field test result for patients with glaucoma was �4.87±3.9 dB, and 70% of these patients had early glaucomatous visual field damage. No statistically significant difference was found between the areas under the receiver operating characteristic curves (AUCs) for the best parameters from the GDx VCC (nerve fiber indicator, AUC=0.91), Stratus OCT (retinal nerve fiber layer inferior thickness, AUC=0.92), and HRT II (linear discriminant function, AUC=0.86). Abnormal results for each of the instruments, after comparison with their normative databases, were associated with strong positive likelihood ratios. Chance-corrected agreement (weighted ) among the 3 instruments ranged from moderate to substantial (0.50-0.72). Conclusions: The AUCs and the sensitivities at high specificities were similar among the best parameters from each instrument. Abnormal results (as compared with each instrument’s normative database) were associated with high likelihood ratios and large effects on posttest probabilities of having glaucomatous visual field loss. Calculation of likelihood ratios may provide additional information to assist theclinicianindiagnosingglaucomawiththeseinstruments.
481 citations
Cites methods from "Scanning Laser Polarimetry to Measu..."
...The general principles of scanning laser polarimetry have been described in detail elsewhere.(17) The GDx VCC is a modified scanning laser polarimetry system with variable corneal compensation....
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Journal Article•
TL;DR: In this article, the authors compared the abilities of scanning laser polarimetry, optical coherence tomography (OCT), short-wavelength automated perimetry (SWAP), and frequency-doubling technology (FDT) perimetric to discriminate between healthy eyes and those with early glaucoma.
Abstract: PURPOSE. To compare the abilities of scanning laser polarimetry (SLP), optical coherence tomography (OCT), short-wavelength automated perimetry (SWAP), and frequency-doubling technology (FDT) perimetry to discriminate between healthy eyes and those with early glaucoma, classified based on standard automated perimetry (SAP) and optic disc appearance. To determine the agreement among instruments for classifying eyes as glaucomatous. METHODS. One eye of each of 94 subjects was included. Healthy eyes (n = 38) had both normal-appearing optic discs and normal SAP results. Glaucoma by SAP (n = 42) required a repeatable abnormal result (glaucoma hemifield test [GHT] or corrected pattern standard deviation [CPSD] outside normal limits). Glaucoma by disc appearance (n = 51) was based on masked stereoscopic photograph evaluation. Receiver operating characteristic (ROC) curve areas, sensitivities, and specificities were calculated for each instrument separately for each diagnosis. RESULTS. The largest area under the ROC curve was found for OCT inferior quadrant thickness (0.91 for diagnosis based on SAP, 0.89 for diagnosis based on disc appearance), followed by the FDT number of total deviation plot points of ≤5% (0.88 and 0.87, respectively), SLP linear discriminant function (0.79 and 0.81, respectively), and SWAP PSD (0.78 and 0.76, respectively). For diagnosis based on SAP, the ROC curve area was significantly larger for OCT than for SLP and SWAP. For diagnosis based on disc appearance, the ROC curve area was significantly larger for OCT than for SWAP. For both diagnostic criteria, at specificities of ≥90% and ≥70%, the most sensitive OCT parameter was more sensitive than the most sensitive SWAP and SLP parameters. For diagnosis based on SAP, the most sensitive FDT parameter was more sensitive than the most sensitive SLP parameter at specificities of ≥90% and ≥70% and was more sensitive than the most sensitive SWAP parameter at specificity of ≥70%. For diagnosis based on disc appearance at specificity of ≥90%, the most sensitive FDT parameter was more sensitive than the most sensitive SWAP and SLP parameters. At specificity ≥ 90%, agreement among instruments for classifying eyes as glaucomatous was poor. CONCLUSIONS. In general, areas under the ROC curve were largest (although not always significantly so) for OCT parameters, followed by FDT, SLP, and SWAP, regardless of the definition of glaucoma used. The most sensitive OCT and FDT parameters tended to be more sensitive than the most sensitive SWAP and SLI' parameters at the specificities investigated, regardless of diagnostic criteria.
455 citations
TL;DR: Although the area under the ROC curves was similar among the best parameters from each instrument, qualitative assessment of stereophotographs and measurements from the OCT and HRT generally had higher sensitivities than measurements fromThe GDx.
Abstract: Subjects and Methods: Forty-one patients with early to moderate glaucomatous visual field loss and 50 healthy subjects were included in the study. The HRT, GDx, and OCT imaging and visual field testing were completed on 1 eye from each subject within a 6-month interval. Statisticaldifferencesinsensitivityatfixedspecificitiesof85%,90%, and 95% were evaluated. In addition, areas under the receiver operating characteristic (ROC) curve were compared. Results: No significant differences were found between the area under the ROC curve and the best parameter from each instrument: OCT thickness at the 5-o’clock inferior temporal position (mean ±S E, 0.87 ±0 .04), HRT mean height contour in the nasal inferior region (mean±SE, 0.86 ±0 .04), and GDx linear discriminant function (mean±SE, 0.84±0.04). Twelve HRT, 2 GDx, and 9 OCT parameters had an area under the ROC curve of at least 0.81. At a fixed specificity of 90%, significant differences were found between the sensitivity of OCT thickness at the 5-o’clock inferior temporal position (71%) and parameters with sensitivities less than 52%. Qualitative assessment of stereophotographs resulted in a sensitivity of 80%. Conclusion: Although the area under the ROC curves was similar among the best parameters from each instrument, qualitative assessment of stereophotographs and measurements from the OCT and HRT generally had higher sensitivities than measurements from the GDx.
377 citations
Cites background from "Scanning Laser Polarimetry to Measu..."
...Details of this instrument and these parameters have been discussed elsewhere.(11,12,21,22,15) Three scans judged to be of acceptable quality were obtained for each test eye....
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References
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TL;DR: It is confirmed that the death of a substantial proportion of optic nerve fibers precedes detectable visual field loss and that no fiber size was completely spared at any stage of atrophy.
558 citations
Journal Article•
TL;DR: The results may indicate that the optic nerve fiber count, and the anatomic reserve capacity in progressive optic neuropathies, are higher in eyes with large optic discs than in Eyes with small optic nerve heads.
Abstract: In the optic nerve head, the optic nerve fibers are represented by the neuroretinal rim. The rim area showing a high interindividual variability is positively correlated with the optic disc size. This study was performed to address the question of whether, in addition to having a larger neuroretinal rim, eyes with large optic discs also have a higher count of optic nerve fibers compared to eyes with small optic nerve heads. Histologic semithin sections of 72 optic nerves of 56 cornea donors were histomorphometrically evaluated using a computerized image analyzer. The optic nerve fiber count increased significantly (P = 0.01) with enlarging optic disc size. The nerve fiber count was positively correlated with the retrobulbar optic nerve cross section area. It decreased with advancing age, with a mean annual loss of about 4,000 fibers. The nerve fiber density per disc area decreased with increasing optic disc area. Mean and median of the minimal nerve fiber diameter was larger in older subjects. The results may indicate that the optic nerve fiber count, and the anatomic reserve capacity in progressive optic neuropathies, are higher in eyes with large optic discs than in eyes with small optic nerve heads. The optic nerve fiber population decreased with advancing age. This is important for progression, pseudoprogression, and prognosis of optic neuropathies. Optic nerve fiber crowding is more marked in eyes with small optic discs than in eyes with large optic nerve heads. The age-related loss of predominantly small optic nerve fibers can potentiate the optic nerve atrophy in glaucoma and Alzheimer's disease, with both damaging preferentially large axons.
474 citations
TL;DR: Quantitating retinal nerve fiber layer thickness may enhance discrimination between glaucomatous and normal eyes earlier than is currently available by anatomic and functional approaches.
Abstract: • We describe a new technique for the measurement of retinal nerve fiber layer thickness and compare its results with histopathologic measurements in the same eyes. For these studies, two fixed monkey eyes were incised and placed on a pedestal in a plastic viewing dish. The eyes were perfused to maintain a pressure between 10 and 20 mm Hg. An ellipsometer, an optical device used to measure the change in polarization of light (retardation), was implemented in a laser tomographic scanner to obtain polarization data from the two monkey retinas. For the 15 measured locations, retardation ranged between a mean (± SD) of 0.9° ± 1.8° and 23.7° ± 0.3°. Subsequently, retinal nerve fiber layer thickness was measured at the imaged points in epoxy resin-embedded sections by an observer masked to the ellipsometry data. These values ranged between 20.4 μm and 213.9 μm. There was an excellent correlation (R =.83) between retardation and the histopathologic measurement of retinal nerve fiber layer thickness. Quantitating retinal nerve fiber layer thickness may enhance discrimination between glaucomatous and normal eyes earlier than is currently available by anatomic and functional approaches.
473 citations
TL;DR: The authors found a large variability of axonal number among their patients, and suspect that the explanation is a selective loss of large nerve fibers.
292 citations
TL;DR: The normal axonal count and axon diameter distribution in 12 normal human eyes was determined and the inferotemporal sector of the nerve had the highest fiber density and the superonasal nerve had higher mean diameters.
260 citations