Comparing measurements of retinal nerve fiber layer thickness obtained on scanning laser polarimetry with fixed and variable corneal compensator

PURPOSE: To compare retinal nerve fiber layer (RNFL) thickness measurements obtained on scanning laser polarimetry (SLP) with commercially available instruments coupled with fixed (FCC) and variable corneal compensator (VCC). METHODS: Forty-two eyes of 42 patients underwent a complete ophthalmologic evaluation and achromatic automated perimetry (24-2 program, SITA standard strategy). Nineteen eyes were healthy (average mean deviation: -0.12 dB +/- 2.26) and 23 glaucomatous (average mean deviation: -4.92 dB +/- 6.49). All patients underwent SLP with both FCC and VCC. Adequate compensation of corneal birefringence on FCC-SLP was checked acquiring macular retardation map (MRM). RNFL thickness was evaluated considering superior and inferior maximum (SM, IM), average thickness and ellipse average (AT, EA), and superior and inferior average (SA, IA). Mean values (+/-SD) for each parameter measured by the two polarimeters were compared and linear regression calculated. The ability of each parameter to discriminate between normal and glaucomatous eyes was evaluated on both polarimeters calculating area under ROC curve. RESULTS: A significant linear correlation for all parameters was noted (r range: 0.65-0.78). VCC produced slightly higher thickness values than FCC, both in normal and glaucomatous eyes. On both polarimeters, area under ROC curve for all parameters discriminated adequately healthy from glaucomatous eyes (range: 0.68-0.81). CONCLUSIONS: In a highly comparable and selected group of normal and glaucomatous eyes, FCC-SLP and VCC-SLP showed considerable concordance in measuring peripapillary RNFL thickness, both for sectorial and global parameters. Proper corneal birefringence compensation provided separation of normal from glaucomatous eyes on both polarimeters.     

Scanning laser polarimetry with enhanced corneal compensation and optical coherence tomography in normal and glaucomatous eyes

PURPOSE: To examine the association between scanning laser polarimetry (SLP), using enhanced (ECC) and variable corneal compensation (VCC) with optical coherence tomography (OCT), and to compare their discriminating ability in the diagnosis of glaucoma. METHODS: Normal and glaucomatous eyes enrolled from four clinical sites underwent complete examination, automated perimetry, SLP-ECC, SLP-VCC, and OCT. Eyes were characterized in two groups based on the typical scan score (TSS): Normal birefringence pattern (NBP) was defined as a TSS of 80 to 100 and abnormal birefringence pattern (ABP) as TSS 相似文献   

Assessment of retinal nerve fiber layer using optical coherence tomography and scanning laser polarimetry in progressive glaucomatous optic neuropathy

PURPOSE: To describe a case of progressive glaucomatous optic neuropathy using scanning laser polarimetry with fixed (SLP-FCC) and variable corneal compensation (SLP-VCC) and optical coherence tomography (OCT). DESIGN: Observational case report. METHODS: A 21-year-old male with juvenile primary open-angle glaucoma developed progression because of noncompliance with therapy. The patient underwent dilated stereoscopic examination and photography of the optic disk, standard automated perimetry (SAP), OCT, and SLP imaging with FCC and VCC at the baseline examination and after four years of follow-up. RESULTS: Optic disk, retinal nerve fiber layer (RNFL) atrophy, and SAP progression was observed. Reduction in mean RNFL thickness (average, superior, inferior) was 18, 18, and 27 microns (OCT); 22, 40, and 17 microns (SLP-FCC); and 6, 12, and 12 microns (SLP-VCC), respectively. CONCLUSIONS: This case demonstrates that digital imaging of the peripapillary RNFL is capable of documentation and measurement of progressive glaucomatous RNFL atrophy.     

Variable corneal compensation improves discrimination between normal and glaucomatous eyes with the scanning laser polarimeter

PURPOSE: The presently available scanning laser polarimeter (SLP) has a fixed corneal compensator (FCC) that neutralizes corneal birefringence only in eyes with birefringence that matches the population mode. A prototype variable corneal compensator (VCC) provides neutralization of individual corneal birefringence based on individual macular retardation patterns. The aim of this study was to evaluate the relative ability of the SLP with the FCC and with the VCC to discriminate between normal and glaucomatous eyes. DESIGN: Prospective, nonrandomized, comparative case series. PARTICIPANTS: Algorithm-generating set consisting of 56 normal eyes and 55 glaucomatous eyes and an independent data set consisting of 83 normal eyes and 56 glaucomatous eyes. TESTING: Sixteen retardation measurements were obtained with the SLP with the FCC and the VCC from all subjects. MAIN OUTCOME MEASURES: Dependency of parameters on age, gender, ethnic origin, and eye side was sought. Logistic regression was used to evaluate how well the various parameters could detect glaucoma. Discriminant functions were generated, and the area under the receiver operating characteristic (ROC) curve was determined. RESULTS: Discrimination between normal and glaucomatous eyes on the basis of single parameters was significantly better with the VCC than with the FCC for 6 retardation parameters: nasal average (P = 0.0003), superior maximum (P = 0.0003), ellipse average (P = 0.002), average thickness (P = 0.003), superior average (P = 0.010), and inferior average (P = 0.010). Discriminant analysis identified the optimal combination of parameters for the FCC and for the VCC. When the discriminant functions were applied to the independent data set, areas under the ROC curve were 0.84 for the FCC and 0.90 for the VCC (P<0.021). When the discriminant functions were applied to a subset of patients with early visual field loss, areas under the ROC curve were 0.82 for the FCC and 0.90 for the VCC (P<0.016). CONCLUSION: Individual correction for corneal birefringence with the VCC significantly improved the ability of the SLP to distinguish between normal and glaucomatous eyes and enabled detection of patients with early glaucoma.     

Relationship between scanning laser polarimetry with enhanced corneal compensation and with variable corneal compensation

PURPOSE: To evaluate the structure-function relationships between retinal sensitivity measured by Humphrey visual field analyzer (HVFA) and the retinal nerve fiber layer (RNFL) thickness measured by scanning laser polarimetry (SLP) with variable corneal compensation (VCC) and enhanced corneal compensation (ECC) in glaucomatous and healthy eyes. METHODS: Fifty-three eyes with an atypical birefringence pattern (ABP) based on SLP-VCC (28 glaucomatous eyes and 25 normal healthy eyes) were enrolled in this cross-sectional study. RNFL thickness was measured by both VCC and ECC techniques, and the visual field was examined by HVFA with 24-2 full-threshold program. The relationships between RNFL measurements in superior and inferior sectors and corresponding retinal mean sensitivity were sought globally and regionally with linear regression analysis in each group. Coefficients of the determination were calculated and compared between VCC and ECC techniques. RESULTS: In eyes with ABP, R2 values for the association between SLP parameters and retinal sensitivity were 0.06-0.16 with VCC, whereas they were 0.21-0.48 with ECC. The association of RNFL thickness with retinal sensitivity was significantly better with ECC than with VCC in 5 out of 8 regression models between SLP parameters and HVF parameters (P<0.05). CONCLUSIONS: The strength of the structure-function association was higher with ECC than with VCC in eyes with ABP, which suggests that the ECC algorithm is a better approach for evaluating the structure-function relationship in eyes with ABP.     

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

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.     

Comparison of optical coherence tomography and scanning laser polarimetry in glaucoma, ocular hypertension, and suspected glaucoma.

BACKGROUND AND OBJECTIVE: To compare the performance of the newest generation optical coherence topography (OCT) and scanning laser polarimetry with variable corneal compensation (SLP-VCC) in eyes with glaucoma, ocular hypertension, and suspected glaucoma. PATIENTS AND METHODS: One eye each of 84 patients (30 with glaucoma, 26 with suspected glaucoma, and 28 with ocular hypertension) was included in the study. Retinal nerve fiber layer (RNFL) thickness was measured with both technologies and thickness parameters were compared in the three groups of eyes. The correspondence of RNFL thickness measurements with visual field function was also studied. RESULTS: Average OCT-RNFL thickness was found to have a statistically significant difference between patients with glaucoma and either suspected glaucoma or ocular hypertension. A statistically significant correlation between the average RNFL thicknesses measured by the two different technologies was shown only in the glaucoma group. A significant correlation with visual field mean deviation was found for superior average RNFL thickness as measured by SLP and for nerve fiber indicator and average and inferior average RNFL thickness as measured by OCT in glaucomatous eyes. Regression analysis indicated nerve fiber indicator to be the most valuable factor in predicting mean deviation. CONCLUSION: RNFL thickness measurements obtained with OCT and SLP-VCC correlate well only in eyes with more advanced glaucomatous damage. The nerve fiber indicator parameter derived by SLP correlated best with mean deviation.     

Comparison of the GDx VCC scanning laser polarimeter and the stratus optical coherence tomograph in the detection of band atrophy of the optic nerve

AIM: To compare the ability of scanning laser polarimeter (SLP) with variable corneal compensation (GDx VCC) and optical coherence tomograph (Stratus OCT) to discriminate between eyes with band atrophy (BA) of the optic nerve and healthy eyes. METHODS: The study included 37 eyes with BA and temporal visual field (VF) defects from chiasmal compression, and 29 normal eyes. Subjects underwent standard automated perimetry (SAP) and retinal nerve fibre layer (RNFL) scans using GDx VCC and Stratus OCT. The severity of the VF defects was evaluated by the temporal mean defect (TMD), calculated as the average of 22 values of the temporal total deviation plot on SAP. Receiver operating characteristic (ROC) curves were calculated. Pearson's correlation coefficients were used to evaluate the relationship between RNFL thickness parameters and the TMD. RESULTS: No significant difference was found between the ROC curves areas (AUCs) for the GDx VCC and Stratus OCT with regard to average RNFL thickness (0.98 and 0.99, respectively) and the superior (0.94; 0.95), inferior (0.96; 0.97), and nasal (0.92; 0.96) quadrants. However, the AUC in the temporal quadrant (0.77) was significantly smaller (P<0.001) with GDx VCC than with Stratus OCT (0.98). Lower TMD values were associated with smaller RNFL thickness in most parameters from both equipments. CONCLUSION: Adding VCC resulted in improved performance in SLP when evaluating eyes with BA, and both technologies are sensitive in detecting average, superior, inferior, and nasal quadrant RNFL loss. However, GDx VCC still poorly discriminates RNFL loss in the temporal quadrant when compared with Stratus OCT.     

Correction for corneal polarization axis improves the discriminating power of scanning laser polarimetry

PURPOSE: Corneal polarization axis (CPA) has been reported to affect retardation measurements obtained with scanning laser polarimetry (SLP). The purpose of this investigation was to prospectively determine whether correction for CPA improves the discriminating power of SLP for detection of mild-to-moderate glaucoma. DESIGN: Cross-sectional analysis of normal and glaucomatous eyes. METHODS: We constructed a noninvasive slit-lamp-mounted device incorporating two crossed linear polarizers and an optical retarder to measure the slow axis of corneal polarization. Complete ocular examination, standard automated perimetry, SLP imaging, and CPA measurements were performed on normal and glaucomatous eyes. One eye/subject was enrolled; if both eyes of a patient were eligible for the study, the right eye was selected. For each of the 13 SLP parameters, logistic regression was used to determine if including CPA in the model influenced the ability to discriminate between normal and glaucomatous eyes. RESULTS: Forty-three normal eyes (average visual field mean defect, -0.53 +/- 1.4 dB) and 33 glaucomatous eyes (average visual field mean defect, -5.93 +/- 6.5 dB) were enrolled. CPA was significantly correlated with summary retardation parameters (average thickness and integral values) in normal (r = 0.72-0.83, P <.001 for all values) and glaucomatous eyes (r = 0.43-0.62, P =.013 to <.001). Including CPA in the model improved the ability to discriminate between normal and glaucomatous eyes for five retardation parameters quantifying retinal nerve fiber layer (RNFL) thickness (range of P values: 0.045-0.001). For inferior average thickness, area under the receiver operating characteristic (ROC) curve increased significantly (P =.002) from 0.70 to 0.78 after accounting for CPA; with a sensitivity set at 80% specificity improved from 33% to 72%. Correlations between visual field corrected pattern standard deviation and average thickness, ellipse average, superior average, and inferior average significantly increased (range of P values,.018-.001) after adjustment for CPA (r = -0.35 and -0.45, -0.38 and -0.47, -0.46 and -0.57, and -0.42 and -0.49, respectively). CONCLUSIONS: Correction for CPA significantly increases the correlation between retinal nerve fiber layer structural damage and visual function and significantly improves the discriminating power of SLP for detection of mild-to-moderate glaucoma.     

The relationship between optical coherence tomography and scanning laser polarimetry measurements in glaucoma

PURPOSE: To investigate the relationship between optical coherence tomography (OCT) and scanning laser polarimetry (SLP) in measuring peripapillary retinal nerve fiber layer (RNFL) thickness in glaucomatous eyes. METHODS: Fifty glaucomatous eyes were evaluated in this study. Evaluations were analyzed two ways. First, parameters of the Stratus OCT (average thickness, superior/inferior average) and GDx VCC (TSNIT average, nerve fiber indicator (NFI), superior/inferior average) were correlated using the Pearson's correlation coefficient (r). Secondly, comparison (r) of these parameters was completed using the mean deviation (MD) of visual field defect. RESULTS: The following parameters were found to be significantly correlated (P < 0.005). TSNIT average/average thickness (r = 0.673), NFI/average thickness (r = -0.742), superior average (r = 0.841), and inferior average (r = 0.736). In the correlation analysis using the severity of visual field defect, all these parameters had statistically meaningful correlations (P < 0.005). CONCLUSIONS: GDx VCC and Stratus OCT are highly correlated in glaucomatous eyes. Therefore, peripapillary RNFL thickness measured by Stratus OCT and GDx VCC may be equally helpful in the diagnosis of glaucoma.     

Quantitative assessment of structural damage in eyes with localized visual field abnormalities

PURPOSE: To evaluate the pattern of structural damage in the macula and peripapillary retinal nerve fiber layer (RNFL) using optical coherence tomography (OCT) and scanning laser polarimetry (SLP-VCC) in glaucomatous eyes with localized visual field defects. DESIGN: Prospective, cross-sectional analysis. METHODS: Complete examination, automated achromatic perimetry (AAP), Stratus OCT imaging (512 A-scans) of the peripapillary retina and macula, and SLP-VCC imaging of the peripapillary RNFL were performed. Thickness values in the retinal segments associated with the visual field defect (glaucomatous segments) were compared with corresponding segments across the horizontal raphe (nonglaucomatous segments) and age-matched normal controls. RESULTS: Forty eyes of 40 patients (20 normal, 20 glaucomatous) were enrolled (mean age, 71 +/- 10 years; range, 50 to 89). Mean RNFL thickness using SLP-VCC and OCT in the nonglaucomatous segments of glaucomatous eyes (54.0 +/- 9.7 microm, 64.7 +/- 19.0 microm) were significantly (P =.009, <0.0001) reduced compared with the thickness measurements in the corresponding segments of age-matched normal subjects (62.5 +/- 9.2 microm, 105.6 +/- 19.0 microm) respectively. No significant (P =.4) differences in the macular thickness measurements were observed between nonglaucomatous (239.0 +/- 19.4 microm) and normal segments (243.5 +/- 15.0 microm). Compared with age-matched controls, RNFL thickness in the nonglaucomatous segment was abnormal in 15 of 20 patients (75%) with SLP-VCC and in 18 of 20 patients (90%) with OCT. Macular thickness in the nonglaucomatous segment was abnormal in 11 of 20 patients (55%). CONCLUSIONS: Diffuse RNFL and retinal ganglion cell loss is present in eyes with localized visual field abnormalities. Detection of localized changes in macular thickness is limited by measurement overlap among normal and glaucomatous eyes.     

Structure-function relationship is stronger with enhanced corneal compensation than with variable corneal compensation in scanning laser polarimetry

PURPOSE: To compare the structure-function relationship between peripapillary retinal nerve fiber layer (RNFL) retardation, measured with scanning laser polarimetry (SLP) with both enhanced and variable corneal compensation (ECC [enhanced corneal compensation] and VCC [variable corneal compensation], respectively; features of the GDx Nerve Fiber Analyzer; Carl Zeiss Meditec, Inc., Dublin, CA), and visual field (VF) sensitivity, measured with standard automated perimetry (SAP) in normal and glaucomatous eyes and the effect of marked atypical birefringence patterns (ABPs) on this relationship. METHODS: Thirty-three healthy subjects, and 68 patients with primary open-angle glaucoma (POAG) took part in the study. ECC and VCC images were taken in one randomly selected eye of each subject. VF tests were also obtained in the same eyes. The structure-function relationship was assessed in six peripapillary sectors and their matching VF areas and was reassessed after eliminating eyes with marked ABPs. RESULTS: Correlations (Spearman's correlation coefficients, r(s)) in the structure-function relationship were generally stronger in images taken with ECC than in those taken with VCC. With ECC, the relationship was significantly more curvilinear when VF sensitivity was expressed in the standard decibel scale and more linear when VF sensitivity was expressed in an antilog scale than with VCC. When eyes with marked ABP images were removed from the analysis, the structure-function relationship with VCC improved, and no statistically significantly differences were found in the relationships between VCC and ECC. CONCLUSIONS: The structure-function relationship between RNFL retardation and SAP VF sensitivity was stronger in images obtained with the GDx ECC than with the GDx VCC (Carl Zeiss Meditec, Inc., Dublin, CA). ABPs, which appeared more markedly with VCC than with ECC, weakened the structure-function relationship.     

Clinical variables associated with glaucomatous injury in eyes with large optic disc cupping.

BACKGROUND AND OBJECTIVE: To characterize the range of retinal nerve fiber layer (RNFL) and standard automated perimetry damage in eyes with large vertical cup-disc ratio (VCDR). PATIENTS AND METHODS: Complete examination, standard automated perimetry, scanning laser polarimetry with variable corneal compensation, and optical coherence tomography (OCT) of the RNFL and optic nerve head were performed. Large VCDR was defined as > or = 0.80 using stereoscopic disc examination and OCT optic nerve head analysis. Structural and functional characteristics were assessed separately in eyes with a disc area of less than 2 mm2, 2 to 2.5 mm2 and greater than 2.5 mm2. RESULTS: Fifty-seven eyes of 57 subjects were enrolled. A broad range in mean deviation (2.0 to -32.8 dB) and mean RNFL thickness with OCT (24.3-100.4 microm) and scanning laser polarimetry with variable corneal compensation (24.0-61.7 microm) was identified. Predictors of standard automated perimetry severity using multiple linear regression were mean RNFL thickness using OCT (P = .001) and scanning laser polarimetry (P = .001), OCT-vertical cup diameter (P = .003), temporal, superior, nasal, inferior, temporal standard deviation (P = .03), and OCT-disc area (P = .04). Eyes with an OCT-disc area of less than 2 mm2 demonstrated significantly greater standard automated perimetry damage, RNFL loss using OCT and scanning laser polarimetry, and OCT-rim area (P = .002, .0007, .03, and < .0001, respectively) compared with eyes with a disc area of greater than 2.5 mm2. CONCLUSIONS: Eyes with large VCDR have a wide range of RNFL atrophy and standard automated perimetry damage. Small optic discs are associated with more advanced glaucomatous injury.     

Enhanced imaging algorithm for scanning laser polarimetry with variable corneal compensation

PURPOSE: To describe and investigate a method of improving assessment of retinal nerve fiber layer (RNFL) morphology with scanning laser polarimetry (SLP) with variable corneal compensation (VCC). METHODS: By neutralizing anterior segment birefringence with a variable compensator, the current VCC method allows direct measurement of RNFL retardation. In the new method, enhanced corneal compensation (ECC), the variable compensator was set to introduce a "bias" birefringence. This bias was removed mathematically for each individual pixel to produce the RNFL image. In 177 eyes of healthy subjects, patients with glaucoma, and subjects with ocular hypertension, retardation images were obtained with both VCC and ECC. RESULTS: In the tested eyes, images obtained with ECC showed the expected RNFL appearance better than those obtained with VCC. In addition, the typical scan score, which quantifies the amount of atypia, was higher with ECC than with VCC. The amount of residual anterior segment birefringence dropped significantly with ECC in the various groups. Measurements of peripapillary RNFL retardation showed reduced temporal and nasal values with ECC, whereas superior and inferior values were not significantly different between VCC and ECC. The dynamic range appeared to have increased with ECC. The accuracy of the TSNIT (temporal, superior, nasal, inferior, temporal) average and inferior average for detecting glaucoma was higher with ECC than with VCC. CONCLUSIONS: 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.     

Scanning laser polarimetry with enhanced corneal compensation for detection of axonal loss in band atrophy of the optic nerve

PURPOSE: To compare the abilities of scanning laser polarimetry (SLP) with enhanced corneal compensation (ECC) and variable corneal compensation (VCC) modes for detection of retinal nerve fiber layer (RNFL) loss in eyes with band atrophy (BA) of the optic nerve. DESIGN: Cross-sectional study. METHODS: Thirty-seven eyes from 37 patients with BA and temporal visual field defect from chiasmal compression and 40 eyes from 40 healthy subjects were studied. Subjects underwent standard automated perimetry and RNFL measurements using an SLP device equipped with VCC and ECC. Receiver operating characteristic (ROC) curves were calculated for each parameter. Pearson correlation coefficients were obtained to evaluate the relationship between RNFL thickness parameters and severity of visual field loss, as assessed by the temporal mean defect. RESULTS: All RNFL thickness parameters were significantly lower in eyes with BA compared with normal eyes with both compensation modes. However, no statistically significant differences were observed in the areas under the ROC curves for the different parameters between GDx VCC and ECC (Carl Zeiss Meditec, Inc, Dublin, California, USA). Structure-function relationships also were similar for both compensation modes. CONCLUSIONS: No significant differences were found between the diagnostic accuracy of GDx ECC and that of VCC for detection of BA of the optic nerve. The use of GDx ECC does not seem to provide a better evaluation of RNFL loss on the temporal and nasal sectors of the peripapillary retina in subjects with BA of the optic nerve.     

Diabetes-associated retinal nerve fiber damage evaluated with scanning laser polarimetry

PURPOSE: To evaluate retinal nerve fiber layer (RNFL) thickness in patients with diabetes mellitus compared with age-matched normal control subjects, to assess the correlation between the RNFL thickness and the severity of retinopathy, and to investigate whether diabetes mellitus is a potential source of abnormal results in glaucoma screening or evaluation with scanning laser polarimetry (SLP). DESIGN: Cross-sectional analysis of normal and diabetic eyes. METHODS: setting: Institutional clinical study. patients: One hundred twenty-eight subjects with type 2 diabetes mellitus and 50 age-matched normal control subjects without glaucoma or glaucoma-suspect. All patients underwent imaging with SLP and repeatable automated perimetry. Subjects with diabetes mellitus were classified into four stages on the basis of the severity of retinopathy that was assessed by dilated funduscopic examination, high-quality fundus color photography, and fluorescein angiography. MAIN OUTCOME MEASURES: The SLP (GDx VCC software, version 5.5.0) parameters. RESULTS: The RNFL thickness in patients with diabetes mellitus was reduced significantly compared with age-matched normal control eyes (P < .01). Moreover, all RNFL thickness parameters of the GDx VCC software decreased significantly as an exacerbation of diabetic retinopathy (P = .0019, P = .0045, P = .0010 for temporal-superior-nasal-inferior-temporal (TSNIT) average, superior average, inferior average, respectively). The nerve fiber indicator also increased significantly (P < .0001), despite an absence of glaucomatous optic nerve damages. CONCLUSION: The RNFL thickness in type 2 diabetes mellitus, which was measured by GDx VCC software, significantly decreased with the severity of diabetic retinopathy. The presence of diabetes mellitus can be a source of false-positive results and overestimation of glaucomatous optic neuropathy when eyes are screened with GDx VCC software.     

Relationship between visual field sensitivity and retinal nerve fiber layer thickness as measured by scanning laser polarimetry

PURPOSE: To evaluate the strength and pattern of the relationship between visual field (VF) sensitivity and retinal nerve fiber layer (RNFL) thickness measurements by scanning laser polarimetry (SLP). METHODS: Fifty-four eyes of 54 normal subjects (age, 42 +/- 15 years; VF mean deviation [MD], -0.69 +/- 1.01 dB) and 51 eyes of 51 glaucoma patients (age, 66 +/- 14 years; VF MD, -6.92 +/- 5.43 dB) were imaged with an SLP using fixed corneal compensation (FCC) and variable corneal compensation (VCC). VF sensitivity was recorded in the dB and the 1/L scales. Linear and logarithmic relationships were sought globally and in six VF sectors. Relationships of VF and RNFL thickness with age were sought in normal subjects. RESULTS: Both VF sensitivity and RNFL thickness declined with age (as determined by the regression slope): -0.13% (P = 0.0005) and -0.64% (P = 0.0001) per year for dB and 1/L VF sensitivity, respectively, and -0.25% (P = 0.003) per year for VCC RNFL thickness. FCC RNFL thickness was not statistically significantly related to age. The relationship of VF sensitivity to VCC global (R(2) = 0.49) and sectoral (R(2) = 0.00-0.47) RNFL thickness was greater than for FCC global (R(2) = 0.12) and sectoral (R(2) = 0.00-0.21) RNFL thickness. Relationships were curvilinear with the dB scale, with logarithmic regression of dB VF sensitivity against RNFL thickness being significantly better than linear regression. Logarithmic regression of 1/L VF sensitivity against RNFL thickness was no better than linear regression for all sectors. There was no relationship between VF sensitivity and RNFL thickness in the temporal peripapillary RNFL sector. CONCLUSIONS: The strength of the structure/function relationships compare well with previous reports in the literature. The relationships were curvilinear with the dB scale and linear with the 1/L scale, and were much stronger with VCC than with FCC RNFL thickness measurements.     

Scanning laser polarimetry with variable corneal compensation and detection of glaucomatous optic neuropathy

BACKGROUND: The aim of this study was to evaluate the ability of scanning laser polarimetry (SLP) parameters provided by commercially available GDx with variable corneal compensator (VCC) to discriminate between healthy and glaucomatous eyes. METHODS: Sixty-five healthy and 59 glaucomatous age-matched patients underwent a complete ophthalmological evaluation, an achromatic automated perimetry (AAP), and SLP with GDx-VCC. One randomly selected eye from each subject was considered. All glaucomatous eyes had reproducible visual field defects. Mean values (+/- SD) of all SLP-VCC parameters measured in the two groups were compared. Area under receiver operating characteristics (AUROC) curve and sensitivities at predetermined specificities of >or=80% and >or=95% for each single parameter were calculated. Moreover, the nerve fiber indicator (NFI) diagnostic accuracy was evaluated calculating positive, negative, and interval likelihood ratios (LRs) at different cutoff values. RESULTS: All SLP parameters were significantly different between the two groups (p<0.001). The NFI showed the best AUROC curve (0.938, SE 0.02) whereas temporal, superior, nasal, inferior, temporal (TSNIT) average was second best (0.897, SE 0.03), and normalized superior area was third (0.879, SE 0.04). At fixed specificity >or=95%, sensitivities ranged from 22% to 79.7% whereas for values >or=80%, sensitivities were in the 44.1-89.8% range. At a cutoff NFI value of 30, positive LR was 17.6 (95% CI: 5.8-53.6) and negative LR was 0.19 (95% CI: 0.11-0.33). Interval LRs for NFI showed that values 40 were associated with large effects on posttest probability. CONCLUSIONS: SLP-VCC allows good discrimination between healthy and glaucomatous eyes. New software-provided parameters NFI, TSNIT average, and normalized superior and inferior areas appear to be reliable in the evaluation of glaucomatous disease. In particular, after evaluation on interval LRs, the NFI showed a high diagnostic accuracy for values 40.     

Enhanced corneal compensation for scanning laser polarimetry on eyes with atypical polarisation pattern

AIM: To investigate the potential advantage of an enhanced corneal compensation algorithm (ECC) compared with variable corneal compensation (VCC) in the analysis of scanning laser polarimetric (SLP) images with atypical retardation pattern (ARP). METHODS: SLP-VCC images with ARP (typical scan score (TSS) <80) of one eye of each of 27 glaucoma patients and 19 healthy subjects were compared with the corresponding SLP-ECC images obtained at the same session. RESULTS: ARP was present in 10.4% of the normals and 15.5% of the glaucoma patients imaged with SLP-VCC over 9 months. In both groups TSS was higher for ECC than for VCC (p<0.001). In glaucoma TSNIT, superior and inferior average thickness values were significantly lower, and TSNIT (measuring ellipse around the optic nerve head in the four (temporal, superior, nasal, inferior) quadrants) standard deviation was significantly higher with ECC than with VCC (p<0.001). In the normal group nerve fibre indicator (NFI) was lower with ECC than with VCC (p=0.007). TSNIT average was smaller and TSNIT standard deviation was higher with ECC (p<0.001). Superior and inferior average thickness did not differ between VCC and ECC in the normal group. CONCLUSIONS: The new ECC software substantially improves polarimetric image analysis on eyes showing atypical polarisation pattern.     

变化角膜补偿器偏振光激光扫描仪对青光眼的临床观察

目的　评价使用变化角膜补偿器的偏振光激光扫描仪 (GDx -VCC)对青光眼患者的定量观察。方法　对青光眼患者 91人 165眼根据有无视野异常及程度分为 :青光眼视野正常组 87眼 ,早期青光眼 5 6眼及中晚期青光眼 2 2眼 ,正常人组 3 6人 3 6眼进行GDx -VCC检查。统计各组平均视神经纤维层厚度 (RNFL)、上方及下方神经纤维层厚度、平均视盘周神经纤维层厚度标准差及视神经纤维索引因素 (NFI)。对各组值进行多组比较统计处理。结果　正常人平均视神经纤维层厚度、上方及下方神经纤维层厚度与视野有异常的青光眼各组值方差分析P <0 0 0 1;与视野正常的青光眼组各对应区域的神经纤维层厚度比较P =0 0 0 9、 0 0 0 5及 0 0 64。结论　使用变化角膜补偿器的偏振光激光扫描仪测量视神经纤维层厚度对正常人与青光眼患者有区别能力 ,能更早于视野反映视神经纤维层异常。