Variable Corneal Compensation Research Articles

Functional MRI Signal Changes in Primary Visual Cortex Corresponding to the Central Normal Visual Field of Patients with Primary Open-Angle Glaucoma

To investigate, by functional magnetic resonance imaging (fMRI), the impact of glaucomatous neuropathy of primary open-angle glaucoma (POAG) on neuronal activity in the primary visual cortex, which corresponds to the central normal visual field. Six POAG patients with asymmetric visual field damage and spared central vision were enrolled in the study. All patients underwent detailed ophthalmic examinations, including visual acuity, intraocular pressure, refraction, gonioscopy, and fundus examination. Scanning laser polarimetry with variable corneal compensation, confocal scanning laser ophthalmoscopy, posterior segment optical coherence tomography (OCT), and SITA-standard 30-2 and 10-2 visual field perimetry were also performed on each patient. Block-design fMRI was then performed. The stimulus was a hemifield checkerboard contrast, reversing at 8 Hz and viewed by the examined eye monocularly during fMRI scanning, with the fellow eye occluded. The blood oxygen level-dependent (BOLD) fMRI signal change in the primary visual cortex corresponding to central visual input from the more severely affected eye was less than that of the fellow eye. Such a difference in fMRI response did not correlate with interocular differences in measurements of scanning laser polarimetry, OCT, and scanning laser ophthalmoscopy, but showed a negative correlation with interocular pattern SD (PSD) difference of visual field analysis. Glaucomatous neuropathy from POAG may lead to decreased cortical activity in the primary visual cortex, which corresponds to the central normal visual field. The resultant cortical depression is not related to interocular differences in results of polarimetry, OCT, and ophthalmoscopy, but is negatively correlated with PSD of visual field analysis.

Structure–Function Correlations Using Scanning Laser Polarimetry in Primary Angle-Closure Glaucoma and Primary Open-Angle Glaucoma

To assess the correlations between retinal nerve fiber layer (RNFL) thickness measured with scanning laser polarimetry and visual field (VF) sensitivity in primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG). Prospective, comparative, observational cases series. Fifty patients with POAG and 56 patients with PACG were examined using scanning laser polarimetry with variable corneal compensation (GDx VCC; Laser Diagnostic Technologies, Inc.) and Humphrey VF analyzer (Carl Zeiss Meditec, Inc.) between August 2005 and July 2006 at Taipei Veterans General Hospital. Correlations between RNFL thickness and VF sensitivity, expressed as mean sensitivity in both decibel and 1/Lambert scales, were estimated by the Spearman rank correlation coefficient (r(s)) and multivariate median regression models (pseudo R(2)). The correlations were determined globally and for 6 RNFL sectors and their corresponding VF regions. The correlation between RNFL thickness and mean sensitivity (in decibels) was weaker in the PACG group (r(s) = 0.38; P = .004; pseudo R(2) = 0.17) than in the POAG group (r(s) = 0.51; P < .001; pseudo R(2) = .31), but the difference in the magnitude of correlation was not significant (P = .42). With Bonferroni correction, the structure-function correlation was significant in the superotemporal (r(s) = 0.62), superonasal (r(s) = 0.56), inferonasal (r(s) = 0.53), and inferotemporal (r(s) = 0.50) sectors in the POAG group (all P < .001), whereas it was significant only in the superotemporal (r(s) = 0.53) and inferotemporal (r(s) = 0.48) sectors in the PACG group (both P < .001). The results were similar when mean sensitivity was expressed as 1/Lambert scale. Both POAG and PACG eyes had moderate structure-function correlations using scanning laser polarimetry. Compared with eyes with POAG, fewer RNFL sectors have significant structure-function correlations in eyes with PACG.

Evaluation of the retinal nerve fiber layer measurements, after photorefractive keratectomy and laser in situ keratomileusis, using scanning laser polarimetry (GDX VCC)

To evaluate the impact of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK), on retinal nerve fiber layer (RNFL) measurements, by means of scanning laser polarimetry (SLP) GDx VCC (with variable corneal compensation). Two groups of 119 myopic patients each were treated by PRK and LASIK respectively; one eye of each patient was randomly selected for the study. RNFL measurements (around the entire calculation circle) was performed in all eyes 1 day before and 1, 3, 6 and 12 months after treatment by using SLP GDx VCC. Corneal compensation was performed in all eyes preoperatively, and in every examination step postoperatively, in order to neutralize the new corneal birefringence. No statistical differences were found between the PRK and LASIK groups, in all preoperative and postoperative RNFL measurements. Only the p values for CCT and mean K-readings preoperatively were statistically significant. PRK and LASIK do not seem to influence the RNFL measurements at 1st, 3rd, 6th and 12th postoperative months when measured with SLP GDx VCC. The corneal compensation reset is necessary in every step of the examination in order to have reproducible results.

Clinical Assessment of Stereoscopic Optic Disc Photographs for Glaucoma: The European Optic Disc Assessment Trial

To determine the diagnostic accuracy of judging optic disc photographs for glaucoma by ophthalmologists. Evaluation of diagnostic test and technology. A total of 243 of 875 invited ophthalmologists in 11 European countries. We determined how well each participant classified 40 healthy eyes and 48 glaucomatous eyes with varying severity of the disease on stereoscopic slides. Duplicate slides were provided for determining intraobserver agreement. All eyes were also imaged with the GDx with variable corneal compensation (GDx-VCC) (Carl Zeiss Meditec AG, Jena, Germany) and the Heidelberg Retina Tomograph (HRT) I (Heidelberg Engineering GmbH, Heidelberg, Germany). Diagnostic accuracies of clinicians were compared with those of the best machine classifiers. Accuracy of classification, expressed as sensitivity, specificity, and overall accuracy. Intraobserver agreement (kappa). The overall diagnostic accuracy of ophthalmologists was 80.5% (standard deviation [SD], 6.8; range, 61.4%-94.3%). The machine classifiers outperformed most observers in diagnostic accuracy; the GDx-VCC nerve fiber indicator and the HRT's best classifier correctly classified 93.2% and 89.8% of eyes, respectively. The intraobserver agreement (kappa) varied between -0.13 and 1.0 and was on average good (0.7). In general, ophthalmologists classify optic disc photographs moderately well for detecting glaucoma. There is, however, large variability in diagnostic accuracy among and agreement within clinicians. Common imaging devices outperform most clinicians in classifying optic discs. Proprietary or commercial disclosure may be found after the references.

Peripapillary Retinal Nerve Fiber Layer Thickness Analysis With Scanning Laser Polarimetry (GDx VCC) in Normal Children

To assess the use of scanning laser polarimeter with variable corneal compensation (GDx VCC) in children; to compare GDx VCC parameters between normal children and adults; and, to evaluate peripapillary retinal nerve fiber layer thickness variation with age in normals. Ninety-eight normal children (mean age 8.5+/-2.8 y; range: 3 to 17) and 96 normal adults (mean age of 47.0+/-20.4 y; range: 18 to 87) underwent GDx VCC testing. Eyes with small or large optic discs were excluded. The "extended parameter table" parameters and mean thickness values of the 4 quadrants and 64 sectors were considered. Differences between age groups, retinal thickness comparisons and age effect were assessed using unpaired t test, analysis of variance, and regression analysis. GDx VCC parameters in children and adults showed wide intersubject variability. All parameters, excluding Symmetry, were significantly greater in children (P<0.05). TSNIT (temporal, superior, nasal, inferior, temporal) average, superior average and inferior average parameters showed a significant age-related thinning (P<0.01), at a rate of 0.043, 0.057, and 0.121 microm/y, respectively. A significant age-related superior and inferior retinal nerve fiber layer thinning was found using GDx VCC. Considering the significant differences between children and adults for most GDx VCC parameters, the built-in adult normative database cannot be applied in children.

Effect of cataract surgery on retinal nerve fiber layer thickness parameters using scanning laser polarimetry (GDxVCC)

Purpose:To study the effect of cataract extraction on the retinal nerve fiber layer (RNFL) thickness, and assessment by scanning laser polarimetry (SLP), with variable corneal compensation (GDx VCC), at the glaucoma service of a tertiary care center in North India.Materials and Methods:Thirty-two eyes of 32 subjects were enrolled in the study. The subjects underwent RNFL analysis by SLP (GDx VCC) before undergoing phacoemulsification cataract extraction with intraocular lens (IOL) implantation (Acrysof SA 60 AT) four weeks following cataract surgery. The RNFL thickness parameters evaluated both before and after surgery included temporal, superior, nasal, inferior, temporal (TSNIT) average, superior average, inferior average, and nerve fiber index (NFI).Results:The mean age of subjects was 57.6 ± 11.7 years (18 males, 14 females). Mean TSNIT average thickness (μm) pre- and post-cataract surgery was 49.2 ± 14.1 and 56.5 ± 7.6 (P = 0.001). There was a statistically significant increase in RNFL thickness parameters (TSNIT average, superior average, and inferior average) and decrease in NFI post-cataract surgery as compared to the baseline values. Mean NFI pre- and post-cataract surgery was 41.3 ± 15.3 and 21.6 ± 11.8 (P = 0.001).Conclusions:Measurement of RNFL thickness parameters by scanning laser polarimetry is significantly altered following cataract surgery. Post the cataract surgery, a new baseline needs to be established for assessing the longitudinal follow-up of a glaucoma patient. The presence of cataract may lead to an underestimation of the RNFL thickness, and this should be taken into account when analyzing progression in a glaucoma patient.

Relationship between standard automated perimetry and retinal nerve fiber layer parameters measured with laser polarimetry

PurposeTo determine the relationship between the structural parameters of the retinal nerve fiber layer (RNFL) obtained by using the scanning laser polarimetry with variable corneal compensation (GDx VCC) and the results of standard automated perimetry (SAP), in normal, ocular hypertensive, preperimetric glaucomas and glaucoma subjects. MethodsA total of 423 eyes of 423 consecutive subjects were prospectively included in the study and classified depending on the basal intraocular pressure, optic nerve head appearance and SAP results into four groups: 87 normal eyes, 192 ocular hypertensive eyes, 70 preperimetric glaucomas and 74 glaucomatous eyes. Pearson's correlation coefficients, between mean deviation (MD), pattern standard deviation, number of points altered in each quadrant, and number of points altered at different probability levels of SAP and structural parameters of RNFL obtained by using GDx VCC, were calculated in the different diagnostic groups. In the glaucoma group correlations between the 52 points tested by 24-2 SITA standard and GDx parameters were also calculated. Regression curves were plotted for the strongest correlations. ResultsWeak or non-significant correlations were found in the normal, ocular hypertensive and preperimetric glaucoma groups. However, the glaucoma group presented weak to moderate correlations between several GDx VCC parameters and the SAP variables analysed. The strongest correlation was observed between the standard deviation TSNIT and the MD (0.460). ConclusionsRNFL parameters measured with the GDx VCC presented weak to moderate correlations with the visual field indices and the number of altered points in the glaucoma group.

Scanning laser polarimetry with variable corneal compensation in migraine patients

Scanning laser polarimetry with variable corneal compensation in migraine patients

Relación entre la perimetría automatizada convencional y los parámetros de la capa de fibras nerviosas de la retina obtenidos con la polarimetría láser

Purpose To determine the relationship between the structural parameters of the retinal nerve fiber layer (RNFL) obtained by using the scanning laser polarimetry with variable corneal compensation (GDx VCC) and the results of standard automated perimetry (SAP), in normal, ocular hypertensive, preperimetric glaucomas and glaucoma subjects. Methods A total of 423 eyes of 423 consecutive subjects were prospectively included in the study and classified depending on the basal intraocular pressure, optic nerve head appearance and SAP results into four groups: 87 normal eyes, 192 ocular hypertensive eyes, 70 preperimetric glaucomas and 74 glaucomatous eyes. Pearson's correlation coefficients, between mean deviation (MD), pattern standard deviation, number of points altered in each quadrant, and number of points altered at different probability levels of SAP and structural parameters of RNFL obtained by using GDx VCC, were calculated in the different diagnostic groups. In the glaucoma group correlations between the 52 points tested by 24-2 SITA standard and GDx parameters were also calculated. Regression curves were plotted for the strongest correlations. Results Weak or non-significant correlations were found in the normal, ocular hypertensive and preperimetric glaucoma groups. However, the glaucoma group presented weak to moderate correlations between several GDx VCC parameters and the SAP variables analysed. The strongest correlation was observed between the standard deviation TSNIT and the MD (0.460). Conclusions RNFL parameters measured with the GDx VCC presented weak to moderate correlations with the visual field indices and the number of altered points in the glaucoma group.

Agreement for Detecting Glaucoma Progression with the GDx Guided Progression Analysis, Automated Perimetry, and Optic Disc Photography

To evaluate the ability of the GDx Variable Corneal Compensation (VCC) Guided Progression Analysis (GPA) software for detecting glaucomatous progression. Observational cohort study. The study included 453 eyes from 252 individuals followed for an average of 46+/-14 months as part of the Diagnostic Innovations in Glaucoma Study. At baseline, 29% of the eyes were classified as glaucomatous, 67% of the eyes were classified as suspects, and 5% of the eyes were classified as healthy. Images were obtained annually with the GDx VCC and analyzed for progression using the Fast Mode of the GDx GPA software. Progression using conventional methods was determined by the GPA software for standard automated achromatic perimetry (SAP) and by masked assessment of optic disc stereophotographs by expert graders. Sensitivity, specificity, and likelihood ratios (LRs) for detection of glaucoma progression using the GDx GPA were calculated with SAP and optic disc stereophotographs used as reference standards. Agreement among the different methods was reported using the AC(1) coefficient. Thirty-four of the 431 glaucoma and glaucoma suspect eyes (8%) showed progression by SAP or optic disc stereophotographs. The GDx GPA detected 17 of these eyes for a sensitivity of 50%. Fourteen eyes showed progression only by the GDx GPA with a specificity of 96%. Positive and negative LRs were 12.5 and 0.5, respectively. None of the healthy eyes showed progression by the GDx GPA, with a specificity of 100% in this group. Inter-method agreement (AC(1) coefficient and 95% confidence intervals) for non-progressing and progressing eyes was 0.96 (0.94-0.97) and 0.44 (0.28-0.61), respectively. The GDx GPA detected glaucoma progression in a significant number of cases showing progression by conventional methods, with high specificity and high positive LRs. Estimates of the accuracy for detecting progression suggest that the GDx GPA could be used to complement clinical evaluation in the detection of longitudinal change in glaucoma.

Correlation of Disc Morphology Quantified on Stereophotographs to Results by Heidelberg Retina Tomograph II, GDx Variable Corneal Compensation, and Visual Field Tests

Quantification of disc morphology by computer-assisted planimetry on stereophotographs and to compare the results with those by other fundus structure imaging devices and visual field tests. Cross-sectional study. Fifteen normal eyes of 15 normal subjects and 69 glaucomatous eyes of 69 open-angle glaucoma patients. Sequential digital stereophotographs of the optic discs were obtained by a nonmydriatic fundus camera. Intraobserver reproducibility for the 3 repeated traces and interobserver reproducibility for the three individual examiners were determined. The obtained results were correlated to those by Heidelberg Retina Tomograph (HRT) II, GDx with variable corneal compensation (VCC) and visual field tests obtained within 2 months of the photography. Optic disc parameters such as disc area, cup area, rim/disc area ratio, vertical cup diameter/disc diameter (Cd/Dd) ratio and rim width/disc diameter (Rw/Dd) ratio at radial arbitrary angles. Interclass correlation coefficients (ICC) and coefficients of variance (CV) for the optic disc parameters and their correlation with HRT II, GDx VCC, and visual field test results. Intra- and interobserver ICC and CV were 0.88 to 0.99, 1.1% to 9.6%, and 0.72 to 0.98, 2.2% to 11.9% for area parameters, 0.81 to 0.92, 2.4% to 4.0% and 0.71 to 0.78, 4.3% to 5.0% for Cd/Dd ratio, and 0.73 to 0.91, 9.2% to 23.0% and 0.65 to 0.82, 16.9% to 27.2% for Rw/Dd ratios, respectively. Significant correlation was seen between disc and cup area and the corresponding parameters by HRT II (r(s) > 0.81; P<0.001), as well as between vertical Cd/Dd ratio and global TSNIT average by GDx VCC and visual field test indices (|r(s)| > 0.51; P<0.001), and between superior and inferior Rw/Dd ratio and their corresponding sectoral HRT II, GDx VCC and visual field test indices (r(s) > 0.31; P<0.006), respectively. Correlation with visual field test indices was comparable among stereophotographs, HRT II, and GDx VCC parameters. Optic disc morphologic parameters quantified on stereophotographs by our software showed satisfactory reproducibility and good correlation with those measured by other fundus structure imaging devices and visual field test results, indicating its clinical usefulness, especially in the mass screening of glaucoma.

Correlation between blue-on-yellow perimetry and scanning laser polarimetry with variable corneal compensation measurements in primary open-angle glaucoma

To investigate the correlation between blue-on-yellow perimetry (B/YP) indices and scanning laser polarimetry with variable corneal compensation (GDx VCC) parameters in primary open-angle glaucoma (POAG) patients, and to evaluate whether the two tests can detect similar glaucomatous damage. One eye each of 86 patients with POAG was chosen. All patients were examined with the Octopus 101 automated perimetry dG2 program using the dynamic strategy/normal method (white-onwhite perimetry, W/WP), with the dG2 program using the dynamic strategy/BY method (blue-on-yellow perimetry, B/YP), and with GDx VCC. Findings were analyzed by using Pearson's correlation analysis. Of the 42 early glaucoma patients, 28 had both B/YP visual field loss and retinal nerve fiber layer (RNFL) defects detected by the GDx VCC measurements, and in 85.7% (24/28) of patients the regions of B/YP visual field defects corresponded to the RNFL defects detected by GDx VCC. All moderate and late glaucoma patients had both B/YP visual field loss and RNFL defects detected by GDx VCC, and in 95.5% (42/44) the regions of B/YP visual field defects corresponded to the RNFL defects detected by GDx VCC. A statistically significant correlation was found between B/YP mean sensitivity (MS) and the temporal-superior-nasal-inferior-temporal (TSNIT) average (r2>0.191, P>0.047) in the early glaucoma group, but no significant correlation was found between the W/WP indices and GDx VCC parameters. In the moderate to late glaucoma group, a low or moderate, but significant, correlation was found between B/YP MS and GDx VCC parameters (r2>0.286-0.405, P>0.001-0.01), with the most correlative parameter with B/YP MS being the TSNIT average. A low but significant correlation was also found between the B/YP mean defect (MD) and TSNIT average, superior average, inferior average, and nerve fiber indicator (NFI) (r2>0.188-0.271, P>0.013-0.044), and a low or moderate significant correlation was also found between the W/WP MS and MD and the GDx VCC parameters. The presence of significant correlations between some B/YP indices and the GDx VCC parameters in glaucoma patients suggests that the two tests can detect similar areas and amounts of glaucomatous damage. These findings raise the possibility that both techniques can be used in clinical examinations to yield convergent data.

Scanning laser polarimetry with variable corneal compensation in migraine patients

This study aimed to compare scanning laser polarimetry measurements of retinal nerve fibre layer (RNFL) thickness in eyes of migraine patients with those in eyes of age-matched, healthy subjects. The study was designed as an observational, prospective, cross-sectional study. It included 57 eyes of 57 patients with migraine with or without aura according to the criteria of the International Headache Society and 44 eyes of 44 age-matched healthy controls. Scanning laser polarimetry images were obtained using a commercial GDx VCC system (Version 5.3.1; Laser Diagnostic Technologies, Inc.). At each sitting, three sets of GDx VCC measurements were acquired for each patient and used in the analysis. Image acquisition was performed in undilated eyes in all subjects. The mean ± standard deviation RNFL average thickness parameter in the migraine subjects was significantly lower than in the control group, at 50.4 ± 4.8 μm versus 54.7 ± 3.4 μm, respectively (p < 0.0001). However, there were no differences between migraine subjects and controls in mean RNFL thickness in superior and inferior areas. In the migraine group the mean migraine disability assessment (MIDAS) score was 34.3 ± 15.3 and the mean number of attacks per year was 17.1 ± 6.9 (range 6-28). The mean RNFL average thickness parameter was significantly correlated with MIDAS score (r = - 0.86, p < 0.0001) and frequency of attacks (r = - 0.86, p < 0.0001). The mean RNFL average thickness parameter was found to be thinner in migraine patients. In addition, we found a strong correlation between migraine severity and RNFL average thickness parameters.

Glaukomdiagnostik mittels Scanning-Laser-Polarimetrie

Scanning laser polarimetry (SLP) is another technology for early glaucoma diagnosis. This technique (represented in the GDx from Carl Zeiss Meditec, Jena, Germany) is based on polarimetry and measures the retinal nerve fiber layer (RNFL) thickness. Compared with previous instruments without customized corneal compensation, the variable corneal compensation technology enables improved differentiation between glaucoma and healthy eyes. Limitations are the atypical birefringence patterns that exist in some eyes, showing false high RNFL values. The newest software uses enhanced corneal compensation (ECC) technology to avoid these atypical patterns and to improve glaucoma diagnosis. Advantages of SLP include independence from drawing a contour line and a reference plane. Follow-up using SLP is limited, but with the use of the new ECC technology, trend and event analyses are possible. Long-term studies will determine the effectiveness of this method.

Relationship of optic nerve and brain conventional and non-conventional MRI measures and retinal nerve fiber layer thickness, as assessed by OCT and GDx: A pilot study

Background Measurement of retinal nerve fiber layer (RNFL) thickness in multiple sclerosis (MS) is gaining increasing attention. Objectives To explore the relationship between RNFL thickness as measured by optical coherence tomography (OCT) and scanning laser polarimetry with variable corneal compensation (GDx), and conventional and non-conventional optic nerve and brain MRI measures. Methods Twelve relapsing–remitting (RR) MS patients (12 affected and 12 unaffected eyes) and 4 age- and sex-matched normal controls (NC) (8 unaffected eyes) were enrolled. Four MS patients had a history of bilateral optic neuritis (ON), four had a history of unilateral ON, and 4 had no history of ON. Optic nerve MRI measurements included the length of T2 lesions, measurement of optic nerve atrophy, magnetization transfer ratio (MTR) and diffusion tensor imaging (DTI) measures. Optic nerve atrophy was measured by a novel method with high reproducibility. Brain MRI measurements included T1 and T2 lesion volumes (LVs) and their relative MTRs, and tissue class specific atrophy, MTR and DTI measures. Measures of RNFL were evaluated with OCT and GDx. We also evaluated both high and low contrast letter acuities (LCLA) in order to determine the relationship between vision, MRI metrics, and retinal structural architecture. Results LCLA, RNFL-OCT and optic nerve radius measures showed more robust differences between NC and MS patients, and between MS patients with affected and unaffected eyes. T2-LV and T1-LV, as well as gray matter atrophy, DTI and MTR measures were related to LCLA and RNFL thickness. Unique additive variance regression models showed that both brain and optic nerve MRI measures independently accounted for about 50% of the variance in LCLA and RNFL thickness. In reverse models, about 20% of the additional independent variance was explained by optic nerve or brain MRI metrics. Conclusions Measurement of RNFL thickness and radius of the optic nerve should be preferred to the other optic nerve MRI measures in clinical studies. Whole brain lesion and GM measures are predictive of impaired visual function with corresponding structural concomitants.

Predictors of atypical birefringence pattern in scanning laser polarimetry

Aim:To evaluate predictors of atypical birefringence patterns (ABP) observed in scanning laser polarimetry.Methods:A total of 179 eyes from 82 normal subjects and 97 glaucoma patients were included. The retinal nerve...

Impact of Atypical Retardation Patterns on Detection of Glaucoma Progression using the GDx with Variable Corneal Compensation

To evaluate the impact of atypical retardation patterns (ARP) on detection of progressive retinal nerve fiber layer (RNFL) loss using scanning laser polarimetry with variable corneal compensation (VCC). Observational cohort study. The study included 377 eyes of 221 patients with a median follow-up of 4.0 years. Images were obtained annually with the GDx VCC (Carl Zeiss Meditec Inc, Dublin, California, USA), along with optic disc stereophotographs and standard automated perimetry (SAP) visual fields. Progression was determined by the Guided Progression Analysis software for SAP and by masked assessment of stereophotographs by expert graders. The typical scan score (TSS) was used to quantify the presence of ARPs on GDx VCC images. Random coefficients models were used to evaluate the relationship between ARP and RNFL thickness measurements over time. Thirty-eight eyes (10%) showed progression over time on visual fields, stereophotographs, or both. Changes in TSS scores from baseline were significantly associated with changes in RNFL thickness measurements in both progressing and nonprogressing eyes. Each 1-unit increase in TSS score was associated with a 0.19-microm decrease in RNFL thickness measurement (P < .001) over time. ARPs had a significant effect on detection of progressive RNFL loss with the GDx VCC. Eyes with large amounts of atypical patterns, great fluctuations on these patterns over time, or both may show changes in measurements that can appear falsely as glaucomatous progression or can mask true changes in the RNFL.

Scanning Laser Polarimetry with Variable Corneal Compensation to Detect Preperimetric Glaucoma Using Logistic Regression Analysis

Background/Aims: To define if a new function improves the capability of the scanning laser polarimetry with variable corneal compensation (GDx-VCC) nerve fiber analyzer in detecting preperimetric glaucoma using 12 retinal nerve fiber layer (RNFL) peripapillary sectors. Methods: Data were obtained in a cross-sectional, hospital-clinic-based study in which 478 eyes from 478 glaucoma suspects were enrolled. All of them underwent ophthalmological examination, static automated perimetry (Humphrey 24-2 Swedish interactive threshold algorithm), optic nerve stereoscopic photography, red-free digital RNFL photography and GDx-VCC examination. The overall intake included 391 normal eyes and 60 preperimetric glaucoma eyes with defects in the fiber layer photographs. Results: The mean values of inferior average, temporal-superior-nasal-inferior temporal average, superior average and the number (nerve fiber indicator) were significantly lower in the eyes with RNFL defects than in the control group, when compared with the obtained linear discriminating function. The area under the curve values for receiver-operating characteristics analysis of the new parameter were 5% better than the best GDx-VCC standard values. Conclusions: Our results confirm that the new function has a better diagnostic reliability in preperimetric glaucoma and confirms the usefulness of morphological diagnosis between normal and early damaged RNFLs.

Thickness of the Retinal Nerve Fibre Layer Estimated With the Scanning Laser Polarimeter in Healthy Children

The scanning laser polarimeter [GDx variable corneal compensation (VCC)] measures the thickness of the retinal nerve fibre layer (RNFL) and has, therefore, a possible potential for the diagnosis and follow-up of glaucoma in children. The aim of the present study is to establish reference values of the RNFL thickness in children. The RNFL thickness was measured with a GDx VCC in 72 children aged 4 to 15 years without ocular diseases. The difference in the temporal-superior-nasal-inferior-temporal (TSNIT) average (TA), superior average (SA), and inferior average (IA) between the boys and the girls was estimated with a t test. A 95% confidence interval (CI) of the TA, SA, and IA was calculated for the whole group and compared with those of 4 previous studies. The reproducibility of the examination was estimated in 10 consecutive children and was expressed as 95% CI of the differences between the repeated measurements. There were no statistically significant differences in the TA, SA, and IA between the boys and girls. The 95% CI for the TA, SA, and IA was 61.1+/-1.5, 73.5+/-2.3, and 73.5+/-2.0 microm, respectively. These values did not overlap with those reported previously in the adult groups, confirming a statistically significant age-related thinning of the RNFL. The 95% CI of the differences between the repeated measurements was -0.4+/-1.4 microm for TA, -1.5+/-3.6 microm for SA, and 1.6+/-3.9 microm for IA, suggesting that the examination was reproducible. The GDx VCC examination is reproducible in children. The present RNFL results should represent useful reference values in the evaluation of pediatric glaucoma.

Twenty-Four Hour Blood Pressure Pattern in Patients With Normal Tension Glaucoma in the Habitual Position

PurposeTo investigate the relationship between blood pressure (BP) parameters in the habitual position and glaucomatous damage at initial presentation in patients with untreated normal tension glaucoma (NTG).MethodsFifty-four eyes from 54 subjects diagnosed with NTG were consecutively enrolled. BP was measured with an automated ambulatory monitoring device in the habitual position during 24-hour in-hospitalization. Patients were classified into three groups: non-dippers, dippers, and over-dippers. corresponded to the degree of reduction in their nocturnal mean arterial pressure (MAP) compared with their diurnal MAP. Regression models were used to evaluate potential risk factors, including: age, pre-admission office intraocular pressure (IOP), central corneal thickness (CCT), and BP parameters. Functional outcome variables for glaucomatous damage included mean deviation (MD) and pattern standard deviation (PSD) on a Humphrey field analyzer (HFA). Anatomic outcome variables were TSNIT score (temporal, superior, nasal, inferior, and temporal) average, superior average, inferior average, and nerve fiber indicator (NFI) score on scanning laser polarimetry with variable corneal compensation (SLP-VCC; GDx-VCC).ResultsMarked systolic blood pressure (SBP), diastolic blood pressure (DBP), and MAP fluctuation were noted in the over-dipper group (p<0.05). A linear regression analysis model revealed that nocturnal trough DBP and MAP, average nocturnal SBP, and MAP were all significantly associated with a decreased average TSNIT score and an increased NFI score.ConclusionsNocturnal BP reduction estimated in the habitual position was associated with structural damage in eyes with NTG. This finding may suggest systemic vascular etiology of NTG development associated with nocturnal BP reduction.