Scanning Laser Polarimetry Parameters Research Articles

Repeatability and Reproducibility of Retinal Nerve Fiber Layer Parameters Measured by Scanning Laser Polarimetry with Enhanced Corneal Compensation in Normal and Glaucomatous Eyes.

Objective. To assess the intrasession repeatability and intersession reproducibility of peripapillary retinal nerve fiber layer (RNFL) thickness parameters measured by scanning laser polarimetry (SLP) with enhanced corneal compensation (ECC) in healthy and glaucomatous eyes. Methods. One randomly selected eye of 82 healthy individuals and 60 glaucoma subjects was evaluated. Three scans were acquired during the first visit to evaluate intravisit repeatability. A different operator obtained two additional scans within 2 months after the first session to determine intervisit reproducibility. The intraclass correlation coefficient (ICC), coefficient of variation (COV), and test-retest variability (TRT) were calculated for all SLP parameters in both groups. Results. ICCs ranged from 0.920 to 0.982 for intravisit measurements and from 0.910 to 0.978 for intervisit measurements. The temporal-superior-nasal-inferior-temporal (TSNIT) average was the highest (0.967 and 0.946) in normal eyes, while nerve fiber indicator (NFI; 0.982) and inferior average (0.978) yielded the best ICC in glaucomatous eyes for intravisit and intervisit measurements, respectively. All COVs were under 10% in both groups, except NFI. TSNIT average had the lowest COV (2.43%) in either type of measurement. Intervisit TRT ranged from 6.48 to 12.84. Conclusions. The reproducibility of peripapillary RNFL measurements obtained with SLP-ECC was excellent, indicating that SLP-ECC is sufficiently accurate for monitoring glaucoma progression.

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

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. 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). 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 -5 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 -15 dB), AUC for TSNIT average improved from 0.832 at a TSS of 90 to 0.947 at 100. 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.

Reproducibility of retinal nerve fiber layer parameters measured with scanning laser polarimetry in healthy eyes

AbstractPurpose To determine the variability of retinal nerve fiber layer (RNFL) parameters measured with scanning laser polarimetry (SLP) with enhanced corneal compensator (GDx ECC) in healthy eyes.Methods Eighty‐two healthy individuals were prospectively selected. Only one eye per subject was randomly included in the study. All participants had intraocular pressure less than 21 mmHg and normal standard automated perimetry (Humphrey 24‐2 SITA Standard). Peripapillary RNFL parameters were measured using the GDxPRO (Carl Zeiss Meditec, Dublin, CA) 3 consecutive times on the same session. Left eye data were converted to a right eye format. The same operator performed all acquisitions with the same device. Intraclass correlation coefficient (ICC), coefficient of variation (COV), and test‐retest variability were calculated for all SLP parameters: TSNIT average, superior average, inferior average, TSNIT standard deviation and the nerve fiber indicator (NFI).Results Mean age was 56.08 ± 9.4 years. The ICC was higher than 0.928 for all SLP parameters. The TSNIT average had the highest ICC (0.967), while the TSNIT standard deviation showed the lowest ICC (0.928). The COVs ranged from 2.4% (TSNIT average) to 21.8% (NFI). Test‐retest variability was 6.55 for the NFI and 2.51 for the TSNIT average.Conclusion The reproducibility of RNFL measurements acquired with the GDxPRO was excellent. Variability was higher for NFI than for other SLP parameters.

Reproducibility and repeatability of retinal nerve fiber layer parameters measured by scanning laser polarimetry with enhanced corneal compensation in glaucomatous eyes

AbstractPurpose To determine the reproducibility and repeatability of retinal nerve fiber layer parameters measured using scanning laser polarimetry (SLP) with enhanced corneal compensation (GDx‐ECC) in glaucoma patients.Methods Fifty‐four consecutive glaucomatous subjects were prospectively selected. All participants underwent a comprehensive eye exam and at least a reliable standard automated perimetry (Humphrey, 24‐2 SITA Standard). Only one eye per patient was randomly included in the statistical analysis. Three scans were acquired during the same visit using the GDxPRO (Carl Zeiss Meditec, Dublin, CA). Two additional scans were obtained within a 2‐month period. Intraclass correlation coefficient (ICC), coefficient of variation (COV), and test‐retest variability were calculated for all SLP parameters.Results Mean age was 58.27 ± 8.9 years (p=0.09) and mean deviation of standard automated perimetry was ‐7.04 ± 7.0 dB. ICCs were higher than 0.91 for all SLP parameters. The nerve fiber indicator (NFI) showed the highest ICC in the intra‐test sequence (0.982; 95% confidence interval: 0.972‐0.989; p&lt;0.001). The TSNIT average showed the lowest COVs (4.40% and 4.71% in the intra‐ and inter‐test, respectively). Test‐retest variability for the NFI ranged from 10.6 to 12.8.Conclusion The GDx‐ECC had an excellent intravisit and intervisit reproducibility in glaucoma patients. SLP is an imaging technology that may be useful in monitoring glaucoma progression. Commercial interest

Correlation between scanning laser polarimetry with and without enhanced corneal compensation and high-definition optical coherence tomography in normal and glaucomatous eyes

To assess the relationship between high-definition optical coherence tomography (HD-OCT) and scanning laser polarimetry (SLP) with variable (VCC) and enhanced (ECC) corneal compensation in measuring peripapillary retinal nerve fibre layer (RNFL) thickness in healthy eyes and those with early-to-moderate glaucomatous VF loss. Healthy volunteers and patients with glaucoma who met the eligibility criteria were enrolled in this prospective, cross-sectional, and observational study. Subjects underwent complete ophthalmologic examination, automated perimetry, SLP-ECC, SLP-VCC and HD-OCT. SLP parameters were recalculated in 90 degrees segments (quadrants) in the calculation circle to be compared. Pearson correlation coefficients and Lin's concordance correlation coefficients were calculated. The p-values < 0.05 were considered statistically significant. Fifty-five normal volunteers (mean age 59.1 years) and 33 patients with glaucoma (mean age 63.8 years) were enrolled. In the glaucoma group, 18 patients (54.5%) had MD ≥ -6.0 dB (early glaucoma) and 15 patients (45.4%) had MD between -6.01 and -12.0 dB (moderate glaucoma). The best correlation between HD-OCT and SLP was found in the superior quadrant thickness, r = 0.74 (0.62-0.82) (p < 0.0001) with SLP-VCC and in the average thickness, r = 0.80 (0.71-0.86) (p < 0.0001) and the superior quadrant thickness r = 0.80 (0.71-0.87) (p < 0.0001) with SLP-ECC. Concordance correlation coefficients obtained for every parameter in our study between HD-OCT and SLP-VCC and between HD-OCT and SLP-ECC were poor. Our results suggest that HD-OCT parameters of RNFL thickness are significantly higher than SLP-VCC and SLP-ECC parameters, and therefore those thickness values are not interchangeable. The HD-OCT and SLP methods are well correlated but concordance is poor. The difference plots show a lack of agreement that changes as a proportion of the mean.

Diagnostic Capability of Scanning Laser Polarimetry with and without Enhanced Corneal Compensation and Optical Coherence Tomography

To compare the abilities of the current commercially available versions of scanning laser polarimetry (SLP) and optical coherence tomography (OCT), SLP-variable corneal compensation (VCC), SLP-enhanced corneal compensation (ECC), and high-definition (HD) OCT, in discriminating between healthy eyes and those with early-to-moderate glaucomatous visual field loss. Healthy volunteers and patients with glaucoma who met the eligibility criteria were consecutively enrolled in this prospective, cross-sectional, observational study. Subjects underwent complete eye examination, automated perimetry, SLP-ECC, SLP-VCC, and HD-OCT. Scanning laser polarimetry parameters were recalculated in 90-degree segments (quadrants) in the calculation circle to be compared. Areas under the receiver operating characteristic curve (AUROCs) were calculated for every parameter in order to compare the ability of each imaging modality to differentiate between normal and glaucomatous eyes. Fifty-five normal volunteers (mean age 59.1 years) and 33 patients with glaucoma (mean age 63.8 years) were enrolled. Average visual field mean deviation was -6.69 dB (95% confidence interval -8.07 to -5.31) in the glaucoma group. The largest AUROCs were associated with nerve fiber indicator (0.880 and 0.888) for the SLP-VCC and SLP-ECC, respectively, and with the average thickness in the HD-OCT (0.897). The best performing indices for the SLP-VCC, SLP-ECC, and HD OCT gave similar AUROCs, showing moderate diagnostic accuracy in patients with early to moderate glaucoma. Further studies are needed to evaluate the ability of these technologies to discriminate between normal and glaucomatous eyes.

Increased Long-term Measurement Variability With Scanning Laser Polarimetry Employing Enhanced Corneal Compensation

To investigate whether the intervisit standard deviation (ISD) of various scanning laser polarimetry parameters is increased, in progressing glaucoma. GDx-variable corneal compensation (VCC) and GDx-enhanced corneal compensation (ECC) measurements, and Octopus G2 visual field tests, were performed at 6-month intervals on 27 healthy subjects and 52 consecutive glaucoma patients. One eye per participant was analyzed. Fifteen patients progressed (on the basis of visual field criteria) and 37 remained stable, during the 2.6+/-0.4 years follow-up. Baseline visual field indices and the stage of glaucoma did not differ between the glaucoma groups. No regression with time was found for any GDx parameter in any group. The ISD of GDx-ECC nerve fiber indicator (NFI), but not GDx-VCC NFI, was significantly higher in progression than in the stable glaucoma group (Mann-Whitney U test with Bonferroni correction, P=0.028). Also, several other ISD values tended to increase in the progressing group. Logistic regression analysis revealed that ISD of NFI [odds ratio (OR)=1.22, P=0.013], inferior average (OR=1.80, P=0.035), and average thickness along the measuring ellipse (OR=2.00, P=0.042), as determined with GDx-ECC (but not with GDx-VCC), all associated with visual field progression, independently of patient age. With GDx-ECC, increase of ISD is an early sign of glaucoma progression, precedes the development of detectable parameter changes, and is associated with visual field progression.

Retinal Nerve Fiber Layer Thickness in Congenital Color Vision Deficiency

To evaluate the thickness of the retinal nerve fiber layer (RNFL) in subjects with congenital red-green color vision deficiency (CVD). This study included 20 healthy subjects with congenital red-green CVD and 22 healthy subjects with normal color vision. After Ishihara test and examinations visual field by automated perimetry, all individuals underwent scanning laser polarimetry to measure the thickness of the RNFL. All scanning laser polarimetry parameters related to RNFL thickness were found to be similar in subjects with congenital CVD and normal color vision (p>0.05). This is the first report suggesting normal thickness of the RNFL in subjects with congenital red-green CVD.

Diagnostic compatibility of structural and haemodynamic parameters in open‐angle glaucoma patients

Current evidence indicates that alteration in ocular blood flow may be relevant in open-angle glaucoma (OAG) patients independent of intraocular pressure (IOP). Presently, the lack of an adequate methodology capable of assessing all vascular beds limits the clinical role of blood flow parameters in glaucoma management. We aimed to compare differences in retinal nerve fibre layer (RNFL) thickness and retrobulbar haemodynamics between OAG patients and healthy age-matched control subjects. Sixty eyes of 30 OAG patients and 30 healthy age-matched controls were enrolled into the prospective, randomized study. Retinal nerve fibre layer thickness was analysed by scanning laser polarimetry (SLP). Standard SLP parameters were determined, including: average temporal, superior, nasal, inferior thickness (TSNIT); superior and inferior averages; TSNIT standard deviation (TSNIT-SD), and nerve fibre indicator (NFI). Retrobulbar haemodynamics were assessed using colour Doppler imaging (CDI). Peak systolic velocity (PSV), end-diastolic velocity (EDV), pulsatility index (PI) and resistivity index (RI) in the ophthalmic artery (OA), central retinal artery (CRA) and short posterior ciliary artery (SPCA) were evaluated. The RNFL in OAG patients was statistically significantly thinner compared with that in age-matched controls: the NFI was 24.9 +/- 10.24 in OAG patients and 16.13 +/- 7.95 in healthy controls (p < 0.05). Statistically significant differences were observed: CRA PSV was 20.54 +/- 7.84 cm/second in OAG subjects and 16.5 +/- 6.19 cm/second in healthy controls (p = 0.0038); OA EDV was 8.99 +/- 4.71 cm/second in OAG subjects and 5.93 +/- 3.23 cm/second in healthy controls (p = 0.0048). Correlation analysis of NFI was in positive association with CRA EDV (r = 0.395; p < 0.05) and CRA PI (r = 0.403; p < 0.05) in OAG subjects, but no statistically significant association was seen in healthy controls. Statistically significant thinning of the RNFL in association with reduced retrobulbar blood flow velocities was observed in OAG patients. Combining ocular structural alterations with ocular circulation assessment may increase our ability to elucidate potential IOP-independent glaucomatous risk factors.

Scanning laser polarimetry: logistic regression analysis for perimetric glaucoma diagnosis

To calculate and validate a linear discriminant function (LDF) for scanning laser polarimetry (SLP) with variable corneal compensation (GDx-VCC) to increase the diagnostic accuracy when using isolated retinal nerve fibre layer (RNFL) parameters to discriminate between healthy and glaucomatous eyes with visual field loss. We prospectively selected two independent samples (teaching and validating sets). The teaching set, comprising 71 consecutive healthy subjects and 73 patients with open-angle glaucoma, was used to calculate the LDF. The validating set, comprising 72 consecutive normal eyes and 76 glaucoma patients, was used to test the performance of the LDF in an independent population. Receiver operating characteristic (ROC) curves were plotted for the validating set to evaluate the diagnostic accuracy of the LDF and the SLP parameters. The obtained function was LDF=-12.20+(0.15 x nasal average)-(23.85 x normalized inferior area)+(1.18 x maximum modulation). The areas under the ROC curve were 0.901 and 0.893 for our LDF and 0.893 and 0.877 for the nerve fibre indicator (NFI) in the teaching and validating populations, respectively. There were no significant differences between these values (P=0.743 in the teaching set, and P=0.458 in the validating set). NFI was the SLP-provided parameter with the best sensitivity-specificity balance. Sensitivities were 57.89% for the LDF and 48.68% for NFI at 95% fixed specificity. The LDF and NFI were the most accurate SLP parameters for diagnosing glaucoma. The LDF yielded the highest sensitivity at 95% fixed specificity to discriminate between normal and glaucoma subjects.

Relationship between Scanning Laser Polarimetry with Enhanced Corneal Compensation and with Variable Corneal Compensation

PurposeTo 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.MethodsFifty-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.ResultsIn 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).ConclusionsThe 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.

Detection of Glaucoma Using Scanning Laser Polarimetry with Enhanced Corneal Compensation

To evaluate and compare the diagnostic accuracies for glaucoma detection of scanning laser polarimetry (SLP) with enhanced corneal compensation (GDx ECC) and variable corneal compensation (GDx VCC; both by Carl Zeiss Meditec, Dublin, CA), according to different levels of disease severity and presence of atypical retardation patterns. The study included 102 eyes of 68 patients with glaucoma and 94 eyes of 55 normal subjects. All patients underwent SLP imaging with ECC and VCC methods on the same day. Severity of disease was based on the AGIS (Advanced Glaucoma Intervention Study) visual field score. An ROC regression model was fitted to evaluate the influence of disease severity and atypical retardation patterns (typical scan score [TSS]) on the diagnostic performance of the SLP parameters for both methods. GDx ECC performed significantly better than GDx VCC in glaucoma detection in patients with more severe atypical retardation patterns. For average disease severity and arbitrarily chosen TSS values of 20, 50, 70, and 100, the ROC curve areas for GDx ECC were 0.910, 0.935, 0.948, and 0.964. Corresponding values for GDx VCC were 0.684, 0.850, 0.920, and 0.975. For lower values of TSS and lower AGIS scores, GDx ECC performed significantly better than GDx VCC. GDx ECC performed significantly better than VCC for diagnosing glaucoma in patients with more severe atypical patterns of retardation and at earlier stages of disease.

Scanning Laser Polarimetry with Enhanced Corneal Compensation and Optical Coherence Tomography in Normal and Glaucomatous Eyes

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. 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 <or= 79. For each of the six SLP parameters and five OCT parameters the areas under the receiver operating characteristic curve (AUROCs) were calculated to compare the discriminating ability of each imaging modality, to differentiate between normal and glaucomatous eyes. Ninety-five normal volunteers and 63 patients with glaucoma were enrolled. Average visual field mean deviation was -4.2 +/- 4.3 dB in the glaucoma group. In eyes with NBP, SLP-ECC had significantly (all P <or= 0.001) greater correlation with OCT average, superior, and inferior retinal nerve fiber layer (RNFL; r = 0.79, 0.67, 0.74) compared with SLP-VCC (r = 0.71, 0.43, 0.37). In eyes with ABP, SLP-ECC had a significantly greater (all P <or= 0.001) correlation with OCT average, superior, and inferior RNFL (r = 0.75, 0.73, 0.83) compared with SLP-VCC (r = 0.51, 0.22, 0.18). The AUROC for OCT inferior average thickness (0.91) was similar (P = 0.26) to the TSNIT (temporal, superior, nasal, inferior, temporal) average obtained using SLP-ECC (0.87) and significantly (P = 0.02) greater than SLP-VCC (0.81). Compared with SLP-VCC, SLP-ECC has significantly stronger correlations with OCT and may improve the discriminating ability for early glaucoma diagnosis.

Diagnostic Accuracy of Scanning Laser Polarimetry with Enhanced versus Variable Corneal Compensation

To compare the diagnostic accuracy of scanning laser polarimetry (SLP) parameters between images taken with enhanced corneal compensation (ECC) and those with variable corneal compensation (VCC) and to explore the effect of atypical birefringence patterns on this accuracy. Cross-sectional observational study. Forty-one healthy subjects and 92 patients with primary open-angle glaucoma. Variable corneal compensation and ECC images were obtained of 1 eye per subject, selected randomly if both eyes were eligible. For both ECC and VCC, the areas under the receiver operating characteristic curves (AUROCs) and the sensitivity at a specificity of > or =95% were calculated per parameter in all eyes. The analyses were reperformed separately in eyes with and without atypical birefringence patterns (ABP) images. The AUROCs and sensitivities at a specificity of > or =95% for various SLP parameters in all eyes and in eyes without ABP images. The diagnostic accuracy for most standard parameters (temporal-superior-nasal-inferior-temporal [TSNIT] average, superior average, inferior average, and TSNIT standard deviation) in all eyes was statistically significantly higher with ECC than with VCC, except for the nerve fiber indicator (NFI). When only eyes without ABP were used for the analysis, the diagnostic accuracy of SLP parameters with VCC improved, and the differences in diagnostic accuracy between ECC and VCC for these parameters lost their statistical significance. Standard SLP parameters (except for the NFI) generally had a higher diagnostic accuracy when eyes were imaged with ECC than with VCC because there were fewer ABP images with ECC than with VCC. Enhanced corneal compensation therefore may be more reliable than VCC for the detection of glaucoma. A future automated classifier, similar to the current NFI, may perform better if it is trained on data obtained with ECC. Clinically, retinal nerve fiber layer images with marked ABP, acquired with either ECC or VCC, should be viewed with caution.

The Influence of Low to Moderate Myopia on Retinal Nerve Fiber Layer as Assessed by Scanning Laser Polarimetry with Variable Corneal Compensator

Purpose: To evaluate the influence of different degrees of myopia on retinal nerve fiber layer (RNFL) as measured by scanning laser polarimetry (SLP) with variable corneal compensator (VCC) in healthy eyes. Methods: One hundred and seventy-four healthy age-matched subjects with low to high myopic and emmetropic eyes underwent RNFL measurement by means of GDxVCC. The GDx parameters included in the analysis were: Temporal-superior-nasal-inferior thickness (TSNIT) average, Superior average, Inferior average, TSNIT standard deviation, Inter-eye symmetry, NFI, Symmetry, Superior ratio, Inferior ratio, Superior/nasal, Maximum modulation, Superior maximum, Inferior maximum, Ellipse modulation, Normalized superior area, Normalized inferior area, Ellipse standard deviation, Ellipse average. The mean value of each SLP parameter of myopic eyes was compared with the mean value of the same parameter of emmetropic eyes. Results: Mean myopia was 3.9 ± 1.5 dpt (range: –2 to –8.25 dpt). TNSIT average was higher in myopic group (p = 0.0111), together with Superior average (p = 0.0244), Symmetry (p < 0.0001) and Ellipse average (p = 0.0111). Two ratio parameters, Superior ratio and Inferior ratio, were higher in emmetropic eyes (p = 0.0179 in both cases). In both the myopic and the emmetropic group, all the SLP assessments of the RNFL fell within the normal range, according to the GDx database. Conclusions: Low to high myopia is not related to clinically relevant variations of SLP parameters, as assessed with GDx-VCC.

Correlation of Retinal Nerve Fiber Layer Measured by Scanning Laser Polarimeter to Visual Field in Ischemic Optic Neuropathy

To evaluate the relationship between retinal nerve fiber layer (RNFL) measurement with scanning laser polarimetry (SLP) and standard automated perimetry (SAP) in nonarteritic anterior ischemic optic neuropathy (NAION). In this prospective observational case series, all subjects (28 eyes with NAION) underwent SAP and SLP. The RNFL retardation measurements and visual field test points were grouped into 6 corresponding sectors. The contralateral uninvolved eye was used as control. The relationship between RNFL retardation and SAP was evaluated with the Spearman nonparametric technique and linear regression analysis. The main outcome measure was correlation of SLP RNFL parameters and SAP. Global and sectoral SLP parameters showed a significant difference in affected eyes compared with controls. The strongest correlations were seen between mean deviation and number (r = -0.524; P = .004), ellipse modulation (r = 0.5026; P = .006), and maximum modulation (r = 0.526; P = .004). Superior sectoral visual field indexes showed a strong correlation with inferior RNFL changes (r = 0.522; P<.008). Linear regression confirmed a strong relationship between the superior sectoral visual field indexes and the inferior RNFL. Scanning laser polarimetry was able to identify structural changes of the RNFL globally and in the inferior SLP sector with functional loss in NAION.

Influência da redução medicamentosa da pressão intra-ocular na medida da espessura da camada de fibras nervosas da retina de olhos hipertensos e glaucomatosos pela polarimetria de varredura a laser

To evaluate changes in retinal nerve fiber layer thickness as measured by scanning laser polarimetry (SLP) after the use of medication to reduce intraocular pressure (IOP) in glaucomatous or ocular hypertensive patients. The authors prospectively enrolled 37 eyes of 37 patients in whom IOP was reduced by more than 25% after the use of medication. The images were obtained before and 15 to 30 days after the introduction of medication. The SLP parameters measured before and after the use of medication were compared using paired Student's t Test. The mean IOP was significantly reduced from 26.57 +/- 4.23 mmHg to 16.54 +/- 2.92 mmHg after the use of medication (p < 0.05). None of the 10 SLP analyzed parameters was significantly affected by the reduction of IOP with medication (p > 0.05). The retinal nerve fiber layer thickness, as measured by SLP, is not affected by the reduction of IOP with medication in patients with glaucoma or ocular hypertension.

Scanning Laser Polarimetry in Pulmonary Tuberculosis Patients on Chemotherapy

The aim of this study was to analyse the thickness of the retinal nerve fibre layer (RNFL) of pulmonary tuberculosis patients on ethambutol and isoniazid. This was a prospective cohort study where patients with newly diagnosed pulmonary tuberculosis requiring chemotherapy, including ethambutol and isoniazid, were imaged using scanning laser polarimetry. Their mean baseline RNFL thickness and various scanning laser polarimetry parameters of both eyes were measured 2 weeks after the commencement of chemotherapy. The measurements were repeated at 3 months and 6 months after treatment. The various parameters of the baseline and the follow-up measurements were compared using paired sample t-test with Bonferroni correction. Twenty-four patients (16 males and 8 females; mean age, 51.0 +/- 17.6 years) were recruited. There was no statistically significant difference between the baseline and the follow-up measurements in RNFL thickness and all other scanning laser polarimetry parameters. In this cohort of subjects, there was no subclinical change in RNFL thickness detected by scanning laser polarimetry in pulmonary tuberculosis patients on chemotherapy, including ethambutol and isoniazid, after 6 months of treatment.

Scanning Laser Polarimetry Using Variable Corneal Compensation in the Detection of Glaucoma with Localized Visual Field Defects

To evaluate the ability of scanning laser polarimetry parameters and a novel deviation map algorithm to discriminate between healthy and early glaucomatous eyes with localized visual field (VF) defects confined to one hemifield. Prospective case-control study. Seventy glaucomatous eyes with localized VF defects and 66 normal controls. A Humphrey field analyzer 24-2 full-threshold test and scanning laser polarimetry with variable corneal compensation were used. We assessed the sensitivity and specificity of scanning laser polarimetry parameters, sensitivity and cutoff values for scanning laser polarimetry deviation map algorithms at different specificity values (80%, 90%, and 95%) in the detection of glaucoma, and correlations between the algorithms of scanning laser polarimetry and of the pattern deviation derived from Humphrey field analyzer testing. There were significant differences between the glaucoma group and normal subjects in the mean parametric values of the temporal, superior, nasal, inferior, temporal (TSNIT) average, superior average, inferior average, and TSNIT standard deviation (SD) (P<0.05). The sensitivity and specificity of each scanning laser polarimetry variable was as follows: TSNIT, 44.3% (95% confidence interval [CI], 39.8%-49.8%) and 100% (95.4%-100%); superior average, 30% (25.5%-34.5%) and 97% (93.5%-100%); inferior average, 45.7% (42.2%-49.2%) and 100% (95.8%-100%); and TSNIT SD, 30% (25.9%-34.1%) and 97% (93.2%-100%), respectively (when abnormal was defined as P<0.05). Based on nerve fiber indicator cutoff values of > or =30 and > or =51 to indicate glaucoma, sensitivities were 54.3% (50.1%-58.5%) and 10% (6.4%-13.6%), and specificities were 97% (93.2%-100%) and 100% (95.8%-100%), respectively. The range of areas under the receiver operating characteristic curves using the scanning laser polarimetry deviation map algorithm was 0.790 to 0.879. Overall sensitivities combining each probability scale and severity score at 80%, 90%, and 95% specificities were 90.0% (95% CI, 86.4%-93.6%), 71.4% (67.4%-75.4%), and 60.0% (56.2%-63.8%), respectively. There was a statistically significant correlation between the scanning laser polarimetry severity score and the VF severity score (R2 = 0.360, P<0.001). Scanning laser polarimetry parameters may not be sufficiently sensitive to detect glaucomatous patients with localized VF damage. Our algorithm using the scanning laser polarimetry deviation map may enhance the understanding of scanning laser polarimetry printouts in terms of the locality, deviation size, and severity of localized retinal nerve fiber layer defects in eyes with localized VF loss.

Correlation Between Polarimetric Retinal Nerve Fiber Layer Thickness and Retinal Sensitivity Determined With Frequency-Doubling Technology

Correlation between polarimetric retinal nerve fiber layer thickness measured with variable corneal compensation and retinal sensitivity measured with frequency-doubling technology (FDT) and standard automated perimetry (SAP) was investigated. Twenty-four consecutive patients with chronic open-angle glaucoma and 17 healthy control subjects (1 randomly selected eye for each subject) were evaluated. For all subjects, quadrant scanning laser polarimetry parameters correlated positively with both FDT and SAP mean sensitivity of the opposite hemifield (P< .001). Global scanning laser polarimetry parameters correlated positively with FDT-mean sensitivity, SAP-mean sensitivity, and FDT-mean deviation, and negatively with SAP-mean deviation (in SAP, mean deviation is positive in case of sensitivity loss) (P < or = .02). The nerve fiber indicator also correlated with FDT-pattern standard deviation and SAP-corrected loss variance (P < or = .01). Using un-logged sensitivity values, no further correlations were found. Our results show that a similar structure-function relationship exists between polarimetric retinal nerve fiber layer thickness determined with variable corneal compensation and retinal sensitivity measured with SAP and FDT.