Variable Corneal Compensation Research Articles

Association Between Retinal Nerve Fiber Layer Thickness and Incident Dementia in the European Prospective Investigation into Cancer in Norfolk Cohort.

Retinal nerve fiber layer (RNFL) thickness may reflect cerebral status. This study assessed the relationship between RNFL thickness and incident all-cause dementia in the European Prospective Investigation into Cancer in Norfolk (EPIC-Norfolk) Eye Study. Glaucoma detection with variable corneal compensation (GDx-VCC) and Heidelberg Retinal Tomograph II (HRT II) derived global mean RNFL thickness from dementia-free participants at baseline within the EPIC-Norfolk Eye Study were analyzed. Incident dementia was identified through linkage to electronic medical records. Cox proportional hazard mixed-effects regression models adjusted for key confounders were used to examine the associations between RNFL thickness and incident dementia in four separate models. 6,239 participants were included with 322 cases of incident dementia and mean age of 67.5-years old, with 49.7% women (median follow-up 13.2-years, interquartile range (11.7 to 14.6 years). Greater RNFL thickness (GDx-VCC) was not significantly associated with a lower risk of incident dementia in the full adjusted model [HR per quartile increase 0.95; 95% CI 0.82-1.10]. Similarly, RNFL thickness assessed with HRT II was also not associated with incident dementia in any model (full adjusted model; HR per quartile increase: 1.06; [95% CI 0.93-1.19]. Gender did not modify any associations under study. GDx-VCC and HRT II derived RNFL thickness are unlikely to be useful predictors of incident dementia. Higher resolution optical imaging technologies may clarify whether there are useful relationships between neuro-retinal morphology and brain measures.

Phase I NT-501 Ciliary Neurotrophic Factor Implant Trial for Primary Open-Angle Glaucoma: Safety, Neuroprotection, and Neuroenhancement.

To assess the safety and efficacy of a ciliary neurotrophic factor (CNTF) intraocular implant on neuroprotection and neuroenhancement in glaucoma. Open-label, prospective, phase I clinical trial. A total of 11 participants were diagnosed with primary open-angle glaucoma (POAG). One eye of each patient was assigned as the study (implant) eye. The study eye was implanted with a high-dose CNTF-secreting NT-501 implant, whereas the other eye served as a control. All patients were followed up for 18 months. Analysis was limited to descriptive statistics. Primary outcome was safety through 18 months after implantation assessed by serial eye examinations, structural and functional testing, and adverse events (AEs) recording. Parameters measured included visual acuity (VA), Humphrey visual field (HVF), pattern electroretinogram, scanning laser polarimetry with variable corneal compensation (GDx VCC), and OCT. These parameters were also used for secondary analysis of efficacy outcome. All NT-501 implants were well tolerated with no serious AEs associated with the implant. The majority of AEs were related to the implant placement procedure and were resolved by 12 weeks after surgery. Foreign-body sensation was the most commonly reported AE and was self-limited to the postoperative period. The most common implant-related AE was pupil miosis; no patients underwent explant. Visual acuity and contrast sensitivity decreased more in fellow eyes than in study eyes (VA,-5.82 vs.-0.82 letters; and contrast sensitivity,-1.82 vs.-0.37 letters, for fellow vs. study eyes, respectively). The median HVF visual field index and mean deviation measurements worsened (decreased) in fellow eyes (-13.0%,-3.9 dB) and improved (increased) in study eyes (2.7%, 1.2 dB). Implanted eyes showed an increase in retinal nerve fiber layer thickness measured by OCT and by GDx VCC (OCT, 2.66 μm vs. 10.16 μm; and GDx VCC, 1.58μmvs. 8.36μm in fellow vs. study eyes, respectively). The NT-501 CNTF implant was safe and well tolerated in eyes with POAG. Eyes with the implant demonstrated both structural and functional improvements suggesting biological activity, supporting the premise for a randomized phase II clinical trial of single and dual NT-501 CNTF implants in patients with POAG, which is now underway. Proprietary or commercial disclosure may be found after the references.

Foveal Phase Retardation Correlates With Optically Measured Henle Fiber Layer Thickness.

This study quantified and compared phase retardation distribution in the central macula with the thickness of the Henle fiber layer (HFL). A scanning laser polarimeter (SLP) was used to acquire 20° × 40° macular-centered images, either with fixed corneal compensation or with variable corneal compensation, in two cohorts of clinically normal subjects (N = 36). Phase retardation maps from SLP imaging were used to generate a macular cross pattern (fixed compensation) or an annulus pattern (variable compensation) centered on the macula. Intensity profiles in the phase retardation maps were produced using annular regions of interest at eccentricities from 0.25° to 3°. Pixel intensity was averaged at each eccentricity, acting as a surrogate for macular phase retardation. Directional OCT images were acquired in the horizontal and vertical meridians in all subjects, allowing visualization of the HFL thickness. HFL thickness was manually segmented in each meridian and averaged. In both cohorts, phase retardation and HFL thickness were highly correlated in the central 3° assessed, providing further evidence that the source of the phase retardation signal in the central macula is dominated by the HFL and that the center of the macula on cross sectional imaging corresponds closely with the center of the macular cross on SLP imaging.

Evaluation of Corneal and Retinal Toxicity in Rheumatoid Arthritis Patients Treated with Hydroxychloroquine

Introduction: The study aimed to assess the ocular toxicity of hydroxychloroquine (HCQ) by confocal microscopy, multifocal electroretinography (mfERG), and scanning laser polarimetry with variable corneal compensation (GDxVCC) in patients with rheumatoid arthritis (RA). Methods: A cross-sectional, comparative case series study was retrospectively conducted on 61 patients under HCQ treatment for RA without fundoscopic anomalies (group 1), 65 RA patients with no HCQ treatment (group 2), and 27 normal subjects (group 3). A comprehensive ophthalmological examination, including confocal microscopy, mfERG, and GDxVCC, was performed in the three groups. Results: In group 1, the duration of treatment ranged from 19 to 96 months (54.9 ± 15.2 months). The mean cumulative dose of HCQ was 446.1 ± 164.0 g (range 114–864 g). Confocal microscopy revealed hyper-reflective abnormal particles in 45 patients (73.8%) and beaded, tortuous fibers in 34 patients (55.7%) in group 1. No corneal change was observed in the other two groups. The mfERG responses in the 6 concentric rings (R1–R6) among the three groups differed except at R3 (all p < 0.05), and data from R1–R6 were not significantly different between groups 2 and 3. The retinal nerve fiber layer thicknesses were statistically thinner in group 1 than in groups 2 and 3 (all p < 0.05). Conclusions: Early signs of corneal and neural retina structure changes were detected in patients with RA treated with HCQ. Whether these findings should be a mark of drug recession still needs further study and more evidence.

Effect of panretinal photocoagulation on the peripapillary retinal nerve fiber layer in diabetic retinopathy patients

OBJECTIVES:To determine the effect of panretinal photocoagulation (PRP) on the peripapillary retinal nerve fiber layer (RNFL) in nonglaucomatous patients with proliferative diabetic retinopathy (PDR).METHODS:This is a prospective, single center, observational study. Thirty-eight eyes of 26 diabetic patients underwent PRP for proliferative diabetic retinopathy. Peripapillary RNFL thickness was measured using scanning laser polarimetry (SLP) with variable corneal compensation (GDx VCC; by Carl Zeiss Meditec, Dublin, CA) and spectral-domain optical coherence tomography (OCT) (Heidelberg Spectralis, Carlsbad, USA) at baseline and 12 months after PRP was performed.RESULTS:Thirty-eight eyes of 26 patients (15 female) with a mean age of 53.7 years (range 26 to 74 years) were recruited. No significant difference was found among all RNFL thickness parameters tested by GDx VCC software (p=0.952, 0.464 and 0.541 for temporal-superior-nasal-inferior-temporal (TSNIT) average, superior average, inferior average, respectively). The nerve fiber indicator (NFI) had a nonsignificant increase (p=0.354). The OCT results showed that the average RNFL thickness (360° measurement) decreased nonsignificantly from 97.2 mm to 96.0 mm at 1 year post-PRP (p=0.469). There was no significant difference when separately analyzing all the peripapillary sectors (nasal superior, temporal superior, temporal, temporal inferior, nasal inferior and nasal thickness).CONCLUSION:Our results suggest that PRP, as performed in our study, does not cause significant changes in peripapillary RNFL in diabetic PDR patients after one year of follow-up.

Follow-up of the retinal nerve fiber layer thickness of diabetic patients type 2, as a predisposing factor for glaucoma compared to normal subjects.

PurposeTo evaluate and follow-up the retinal nerve fiber layer (RNFL) thickness in patients with diabetes mellitus type 2 compared to a group of healthy individuals with similar demographic characteristics.Patients and methodsThis is a prospective, noninvasive, observational case series study. For the purposes of the study, 27 eyes of diabetic patients without diabetic retinopathy, 24 eyes of patients with mild retinopathy, and 25 normal age-matched subjects (control group [CG]) were examined. All participants underwent complete ophthalmological examination and imaging with GDx variable corneal compensation scanning laser polarimetry. Follow-up was 2 years for all three groups.ResultsThe mean inferior average was statistically significantly lower in both diabetic groups compared to CG at baseline examination and during follow-up. The nerve fiber indicator (NFI) was higher in both diabetic groups compared to CG, both at baseline examination and during follow-up. The NFI was 21.7±11.9 and 22.0±11.8 for the diabetic group without retinopathy, 20.8±9.6 and 21.9±9.8 for the group with mild retinopathy, and 15.3±5.4 and 15.9±5.5 for the normal subjects, at baseline and 24 months, respectively. There was no statistically significant reduction of the RNFL thickness in all three groups compared to baseline examination.ConclusionThis is the first long-term study documenting the RNFL thickness in diabetic patients in comparison with normal controls. Although the lower RNFL was found thinner in diabetics, the 2-year follow-up showed no significant reduction of RNFL thickness in all groups, indicating that RNFL damage may occur early in diabetic patients.

Correlation in retinal nerve fibre layer thickness in uveitis and healthy eyes using scanning laser polarimetry and optical coherence tomography.

To evaluate the correlation of retinal nerve fibre layer (RNFL) thickness measured using spectral domain optical coherence tomography (SD-OCT) and scanning laser polarimetry (SLP) in uveitic eyes compared with healthy eyes. A descriptive, observational, prospective, consecutive, cross-sectional, controlled, monocentre case series was conducted from May to October 2015. Clinical characteristics, best-corrected visual acuity, intraocular pressure, RNFL thickness measurement with SD-OCT and SLP using GDx variable corneal compensation (GDx VCC) were performed for each patient. An evaluation of anterior chamber inflammation with laser flare-cell meter was also carried out. Correlations between SD-OCT and GDx VCC RNFL measurement were evaluated by linear regression analysis. Fifty-four patients were included and divided into two groups: 50 healthy eyes in 29 patients and 42 uveitic eyes in 25 patients. The mean RNFL thickness was 98.08(±8.42) and 113.21(±20.53) μm in the healthy group and the uveitic group, respectively, when measured with SD-OCT (p<0.001); and 56.43(±5.24) and 58.77(±6.67) μm, respectively, when measured with GDx VCC (p=0.078). There was a strong correlation between total average RNFL thickness measured using SD-OCT and GDX (r=0.48, p<0.001) in healthy eyes but there was no correlation in the uveitic eyes (r=0.2, p=0.19). RNFL thickness was significantly greater when measured using SD-OCT in active uveitis as compared with GDx. There was no correlation between the RNFL thickness measurements obtained using the two techniques in uveitic eyes. The discrepancies between the results suggest that for these patients both techniques should be used in conjunction to obtain an accurate measurement of RNFL. IRB 00008855 Société Française d'Ophtalmologie IRB#1.

Combining Frequency Doubling Technology Perimetry and Scanning Laser Polarimetry for Glaucoma Detection.

To determine the ability of frequency doubling technology (FDT) and scanning laser polarimetry with variable corneal compensation (GDx-VCC) to detect glaucoma when used individually and in combination. One hundred ten normal and 114 glaucomatous subjects were tested with FDT C-20-5 screening protocol and the GDx-VCC. The discriminating ability was tested for each device individually and for both devices combined using GDx-NFI, GDx-TSNIT, number of missed points of FDT, and normal or abnormal FDT. Measures of discrimination included sensitivity, specificity, area under the curve (AUC), Akaike's information criterion (AIC), and prediction confidence interval lengths. For detecting glaucoma regardless of severity, the multivariable model resulting from the combination of GDx-TSNIT, number of abnormal points on FDT (NAP-FDT), and the interaction GDx-TSNIT×NAP-FDT (AIC: 88.28, AUC: 0.959, sensitivity: 94.6%, specificity: 89.5%) outperformed the best single-variable model provided by GDx-NFI (AIC: 120.88, AUC: 0.914, sensitivity: 87.8%, specificity: 84.2%). The multivariable model combining GDx-TSNIT, NAP-FDT, and interaction GDx-TSNIT×NAP-FDT consistently provided better discriminating abilities for detecting early, moderate, and severe glaucoma than the best single-variable models. The multivariable model including GDx-TSNIT, NAP-FDT, and the interaction GDx-TSNIT×NAP-FDT provides the best glaucoma prediction compared with all other multivariable and univariable models. Combining the FDT C-20-5 screening protocol and GDx-VCC improves glaucoma detection compared with using GDx or FDT alone.

Retinal Blood Vessel Distribution Correlates With the Peripapillary Retinal Nerve Fiber Layer Thickness Profile as Measured With GDx VCC and ECC.

Purpose:Aim of the present study was to evaluate whether there is a correlation between retinal blood vessel density (RVD) and the peripapillary retinal nerve fiber layer (RNFL) thickness profile.Methods:RNFL thickness of 106 healthy subjects was measured using scanning laser polarimetry, GDx variable corneal compensation (VCC), and GDx enhanced corneal compensation (ECC). A proprietary software was developed in MATLAB to measure the peripapillary retinal vessels using scanning laser ophthalmoscopy fundus images, centered on the optic disc measured by Cirrus spectral domain optical coherence tomography. The individual retinal vessel positions and thickness values were integrated in a 64-sector RVD profile and intrasubject and intersubject correlations were calculated.Results:The mean R value±SD for intrasubject correlation between RVD and RNFL thickness measured with GDx VCC and GDx ECC was 0.714±0.157 and 0.629±0.140, with 105 of 106 subjects presenting significant correlations. In the intersubject linear regression analysis for GDx VCC, 33 of 64 (52%) sectors presented a significant Pearson correlation coefficient between RNFL thickness and RVD values, with a mean R value of 0.187±0.135 (P<0.05).Conclusions:Peripapillary RNFL thickness profiles correlate with the RVD over 50% of the sectors and might explain up to 26% of the interindividual variance of the peripapillary RNFL thickness values as measured with GDx VCC. To our opinion, taking into account RVD might reduce interindividual variation in peripapillary RNFL thickness profiles measured with scanning laser polarimetry.

Concentric macular rings sign in patients with foveal hypoplasia.

We describe a sign that can be used as a rapid and noninvasive adjunct to aid in the diagnosis of foveal hypoplasia. To describe a concentric macular rings sign found on infrared reflectance (IRR) images in patients with foveal hypoplasia. We studied 13 patients with foveal hypoplasia (7 with ocular albinism [OA], 5 with oculocutaneous albinism [OCA], and 1 with aniridia) at a tertiary ophthalmology center with access to electrodiagnostic services from February 18, 2009, through April 9, 2013. All patients and an age-matched control participant underwent a complete clinical examination, electroretinography (full field and pattern), visual evoked potentials, fundus autofluorescence IRR, and optical coherence tomography (OCT). One patient with OA and the control participant also underwent scanning laser polarimetry with variable corneal compensation (GDx VCC). Thirteen patients (6 girls and 7 boys), with a mean age of 5.8 years (range, 3-11 years), were included in the study. Seven patients were diagnosed as having OA and had minimal clinical signs (fine nystagmus in 2 patients and subtle iris transillumination in 5 patients). Five patients with OCA and 1 with aniridia were also included. In 12 patients, OA and OCA were confirmed with 5-channel visual evoked potentials (optic nerve misrouting). Whenever OCT was performed, foveal hypoplasia was indicated by the lack of foveal dip. The macula lacked the foveal attenuation normally seen with fundus autofluorescence, and a concentric macular rings reflex was seen with IRR in all 13 patients and with GDx VCC in 1 patient. A normal bowtie reflex was seen with IRR and GDx VCC in the age-matched control participant. Our findings suggest that concentric macular rings seen on IRR or GDx VCC can occur in patients with foveal hypoplasia and can therefore aid in the diagnosis, especially in patients with minimal clinical signs (mild OA) or in cases in which OCT cannot be performed (young patients or patients with high-amplitude nystagmus).

Corneal Biomechanical Properties and Glaucoma-Related Quantitative Traits in the EPIC-Norfolk Eye Study

We examined the association of corneal hysteresis (CH) with Heidelberg retina tomograph (HRT)- and Glaucoma Detection with Variable Corneal Compensation scanning laser polarimeter (GDxVCC)-derived measures in a British population. The EPIC-Norfolk Eye Study is nested within a multicenter cohort study--the European Prospective Investigation of Cancer. Ocular response analyzer (ORA), HRT3, and GDxVCC measurements were taken at the research clinic. Three ORA measurements were taken per eye, and the single best value used. Participants meeting predefined criteria were referred for a second examination, including Goldmann applanation tonometry (GAT) and central corneal thickness (CCT) measurement. Generalized estimating equation models were used to examine the associations of CH with HRT and GDxVCC parameters, adjusted for disc area. The GDxVCC analyses were adjusted further for typical scan score to handle atypical retardation. There were complete research clinic data from 5134 participants. Corneal hysteresis was associated positively with HRT rim area (P < 0.001), and GDxVCC retinal nerve fiber layer (RNFL) average thickness (P = 0.006) and modulation (P = 0.003), and associated negatively with HRT linear cup-to-disc ratio (LCDR, P < 0.001), after adjustment for Goldmann-correlated IOP and other possible confounders. In the 602 participants undergoing the second examination, CH was associated negatively with LCDR (P = 0.008) after adjustment for GAT, CCT, and other possible confounders. Lower CH was associated with HRT and GDxVCC parameters in a direction that is seen in glaucoma and with ageing. Further research is required to establish if this is a causal relationship, or due to residual confounding by age, IOP, or CCT.

Visual Evoked Potential and Magnetic Resonance Imaging are More Effective Markers of Multiple Sclerosis Progression than Laser Polarimetry with Variable Corneal Compensation

Background: The aim of our study was to assess the role of laser polarimetry and visual evoked potentials (VEP) as potential biomarkers of disease progression in multiple sclerosis (MS).Participants: A total of 41 patients with MS (82 eyes) and 22 age-related healthy volunteers (44 eyes) completed the study. MS patients were divided into two groups, one (ON) with a history of optic neuritis (17 patients, 34 eyes) and another group (NON) without it (24 patients, 48 eyes). The MS patients and controls underwent laser polarimetry (GDx) examination of the retinal nerve fiber layer (RNFL). In the MS group, we also examined: Kurtzke “expanded disability status scale” (EDSS), the duration of the disorder, VEP – latency and amplitude, and conventional brain magnetic resonance imaging (MRI). Our results were statistically analyzed using ANOVA, Mann–Whitney, and Spearman correlation analyses.Results: In the MS group, brain atrophy and new T2 brain lesions in MRI correlated with both VEP latencies and amplitudes. Separate comparisons revealed VEP latency testing to be less sensitive in ON than in NON-patients. In ON patients, VEP amplitudes correlated mildly with brain atrophy (r = −0.15) and strongly with brain new MRI lesions (r = −0.8). In NON-patients, highly significant correlation of new MRI brain lesions with VEP latencies (r = 0.63, r = 0.6) and amplitudes (r = −0.3, r = −4.2) was found. EDSS also correlated with brain atrophy in this group (r = 0.5). Our study did not find a correlation of GDx measures with MRI tests. The GDx method was not able to detect whole brain demyelinization and the degeneration process, but was only able to reveal the involvement of optic nerves in ON and NON-patients.Conclusion: In our study, we found that both methods (VEP and GDx) can be used for the detection of optic nerve damage, but VEP was found to be superior in evaluating whole brain demyelinization and axonal degeneration. Both VEP and MRI, but not GDx, have an important role in monitoring disease progression in MS patients, independent of the ON history.

Structure-Function Relationship Between the Octopus Perimeter Cluster Mean Sensitivity and Sector Retinal Nerve Fiber Layer Thickness Measured With the RTVue Optical Coherence Tomography and Scanning Laser Polarimetry

To determine structure-function relationship between each of 16 Octopus perimeter G2 program clusters and the corresponding 16 peripapillary sector retinal nerve fiber layer thickness (RNFLT) values measured with the RTVue-100 Fourier-domain optical coherence tomography (RTVue OCT) and scanning laser polarimetry with variable corneal compensation (GDx-VCC) and enhanced corneal compensation (GDx-ECC) corneal compensation. One eye of 110 white patients (15 healthy, 20 ocular hypertensive, and 75 glaucoma eyes) were investigated. The Akaike information criterion and the F test were used to identify the best fitting model. Parabolic relationship with logarithmic cluster mean sensitivity and linear sector RNFLT values provided the best fit. For RTVue OCT, significant (P<0.0001) coefficients of determination (R) were found for all 16 RNFLT sectors. The R values were highest for the temporal, superotemporal, and inferotemporal RNFLT sectors (0.4483 to 0.5186). For GDx-VCC/ECC, significant (P<0.01) parabolic relationship was seen for all but the temporal and nasal RNFLT sectors. The overall highest R value (0.6943) was found for a superotemporal RNFLT sector with GDx-ECC. For some RNFLT sectors, the goodness of fit differed significantly between the imaging methods. Structure-function relationship was similar for the total population and the glaucoma subgroup, whereas no relationship (P>0.05) was found for the control eyes. Mean sensitivity of the Octopus visual field clusters showed significant parabolic relationship with the corresponding peripapillary RNFLT sectors. The relationship was more general with the RTVue OCT than GDx-VCC or GDx-ECC. The results show that visual field clusters of the Octopus G program can be applied for detailed structure-function research.

The glaucoma detection capability of spectral-domain OCT and GDx-VCC deviation maps in early glaucoma patients with localized visual field defects

To evaluate and compare the glaucoma detection capabilities afforded by retinal nerve fiber layer (RNFL) thickness and deviation maps obtained using Cirrus spectral domain optical coherence tomography (Cirrus OCT), and GDx employing variable corneal compensation (GDx-VCC) in glaucoma patients with early, localized visual field (VF) loss. This prospective controlled, comparative study was performed on 42 eyes with localized VF defects, and 42 age/refractive error-matched healthy eyes. All participants were imaged by both imaging devices at the same visit. The area of the RNFL defect in each deviation map, corresponding to a VF defect, was analyzed by direct counting of color-coded superpixels in each device. Receiver operating characteristic (ROC) curves were constructed and compared between Cirrus OCT and GDx-VCC. The areas under the ROCs (AUCs) of RNFL quadrant thicknesses in hemifields with visual field (VF) defects did not differ significantly (Cirrus OCT; 0.961, GDx-VCC; 0.919, P = 0.07). However, Cirrus OCT afforded a better diagnostic ability, by deviation map analysis, than did GDx-VCC (0.972 vs 0.887, P = 0.02). The RNFL thicknesses assessed by either Cirrus OCT or GDx-VCC were comparable in terms of early glaucoma diagnostic capability. However, when areas containing RNFL defects were analyzed via deviation mapping, Cirrus OCT was better than GDx-VCC.

Retinal nerve fiber layer in primary open-angle glaucoma with high myopia determined by optical coherence tomography and scanning laser polarimetry

Background Fundus changes associated with high myopia (HM) may mask those associated with primary open-angle glaucoma (POAG). This study aim to determine the characteristics of RNFL thickness changes in patients with both POAG and HM and compare these to changes in patients with only HM. The diagnostic capabilities of both OCT and GDxVCC in this subset of patients are also evaluated. Methods Twenty-two eyes with POAG and HM (spherical equivalent (SE) between −6.0 and −12.0 D) were evaluated, and 22 eyes with HM were used for comparison. Characteristic retinal nerve fiber layer (RNFL) thickness profiles in patients with POAG and HM were examined using optical coherence tomography (OCT) and scanning laser polarimetry with variable corneal compensation (GDxVCC), and the diagnostic capabilities of these imaging modalities were compared. RNFL parameters evaluated included superior average (Savg-GDx), inferior average (Iavg-GDx), temporal-superior-nasal- inferior-temporal (TSNIT) average, and nerve fiber indicator (NFI) on GDxVCC and superior average (Savg-OCT), inferior average (Iavg-OCT), nasal average (Navg-OCT), temporal average (Tavg-OCT), and average thickness (AvgThick-OCT) on OCT (fast RNFL scan). Visual field testing was performed and defects were evaluated using mean defect (MD) and pattern standard deviation (PSD). Results The RNFL parameters (P &lt;0.05) significantly different between groups included Savg-GDx, Iavg-GDx, TSNIT average, NFI, Savg-OCT, Iavg-OCT, Tavg-OCT, and AvgThick-OCT. Significant correlations existed between TSNIT average and AvgThick-OCT (r=0.778), TSNIT average and MD (r=0.749), AvgThick-OCT and MD (r=0.647), TSNIT average and PSD (r=−0.756), and AvgThick-OCT and PSD (r=−0.784). The area under the receiver operating characteristic curve (AUROC) values of TSNIT average, Savg-GDx, Iavg-GDx, NFI, Savg-OCT, Iavg-OCT, Navg-OCT, Tavg-OCT, and AvgThick-OCT were 0.947, 0.962, 0.973, 0.994, 0.909, 0.917, 0.511, 0.906, and 0.913, respectively. The NFI AUROC was the highest value. Conclusions RNFL thickness was significantly lower in all but the nasal quadrant in patients with POAG and HM, compared to patients with only HM. Measurements with OCT and GDxVCC were well-correlated, and both modalities detected RNFL thickness changes. However, GDxVCC was better than OCT in detecting POAG in HM patients.

Evaluation of retinal nerve fiber layer thickness parameters in myopic population using scanning laser polarimetry (GDxVCC)

Myopia presents a significant challenge to the ophthalmologist as myopic discs are often large, tilted, with deep cups and have a thinner neuroretinal rim all of which may mimic glaucomatous optic nerve head changes causing an error in diagnosis. To evaluate the retinal fiber layer (RNFL) thickness in low, moderate and high myopia using scanning laser polarimetry with variable corneal compensation (GDxVCC). One hundred eyes of 100 emmetropes, 30 eyes of low myopes (0 to - 4 D spherical equivalent(SE), 45 eyes with moderate myopia (- 4 to - 8D SE), and 30 eyes with high myopia (- 8 to - 15D SE) were subjected to retinal nerve fiber layer assessment using the scanning laser polarimetry (GDxVCC) in all subjects using the standard protocol. Subjects with IOP > 21 mm Hg, optic nerve head or visual field changes suggestive of glaucoma were excluded from the study. The major outcome parameters were temporal-superior-nasal-inferiortemporal (TSNIT) average, the superior and inferior average and the nerve fibre indicator (NFI). The TSNIT average (p = 0.009), superior (p = 0.001) and inferior average (p = 0.008) were significantly lower; the NFI was higher (P less than 0.001) in moderate myopes as compared to that in emmetropes. In high myopia the RNFL showed supranormal values; the TSNIT average, superior and inferior average was significantly higher(p less than 0.001) as compared to that in emmetropes. The RNFL measurements on scanning laser polarimetry are affected by the myopic refractive error. Moderate myopes show a significant thinning of the RNFL. In high myopia due to peripapillary chorioretinal atrophy and contribution of scleral birefringence, the RNFL values are abnormally high. These findings need to be taken into account while assessing and monitoring glaucoma damage in moderate to high myopes on GDxVCC.

Glaucoma diagnostics

Glaucoma diagnostics

African Descent and Glaucoma Evaluation Study

The purpose of the study is to determine the degree of intereye asymmetry of optic disc topography and retinal nerve fiber layer (RNFL) thickness in healthy individuals of African descent (AD) and European descent (ED). Observational, clinical study. Five hundred nineteen healthy individuals (AD, n=262, mean age=44.9 years; ED, n=257, mean age=47.1 years) from the African Descent and Glaucoma Evaluation Study and Diagnostic Innovations in Glaucoma Study were tested using Heidelberg retina romograph (HRT), GDx variable corneal compensation (GDx-VCC), and standard, automated perimetry within 6 months of one another. HRT-II measurements included cup area, cup volume, rim area, and rim volume. GDx-VCC measurements included average RNFL thickness. Intereye asymmetry was calculated as the absolute value of the differences in measurements between the right and left eye. AD participants showed significantly higher median asymmetry in cup volume and rim volume (P<0.001 and 0.033, respectively) compared with ED participants. The effect of race lost significance after adjustment for mean disc area and disc area asymmetry in multivariable models. Axial length asymmetry was not correlated with increased asymmetry in any of this study's asymmetry parameters. Normal ranges of asymmetry for the HRT-II measurements of cup area (up to 0.39 mm), cup volume (up to 0.15 mm), rim area (up to 0.45 mm), and rim volume (up to 0.22 mm) were derived, as were asymmetry ranges for GDx-VCC-measured average RNFL thickness (up to 6.25 μm). The effect of race was no longer significant after adjustment for mean disc area and disc area asymmetry. Individuals with asymmetries with magnitudes greater than those of the normal ranges could be considered as suspicious for glaucoma.

Advances in technology helps in early detection of vision disorders

Advances in technology helps in early detection of vision disorders

Rates of retinal nerve fibre layer thickness change in glaucoma patients and control subjects

To examine the rates of retinal nerve fibre layer thickness (RNFLT) change in glaucoma patients and healthy, age-similar control subjects with three techniques: scanning laser polarimetry with variable corneal compensation (VCC) and enhanced corneal compensation (ECC), and time-domain optical coherence tomography (OCT). Sixty-one patients and thirty-three controls were examined with each technique and with standard automated perimetry (SAP) every 6 months. Rates of global RNFLT change and SAP mean deviation (MD) change were estimated with linear mixed-effects models. The median (interquartile range) baseline age was 64.4 (58.2, 71.0) years for patients and 62.4 (56.3, 70.1) years for controls (P=0.56). There was a median of seven examinations over 3.1 years for patients and six examinations in 3.0 years for controls. Baseline visual field MD and RNFLT for all imaging modalities were significantly lower (P<0.01) in patients compared with controls. Rates of RNFLT change were not significantly different between patients and controls (P≥0.19). Mean rates of VCC-measured RNFLT change were -0.18 and -0.37 μm per year in patients and controls, whereas the respective figures for ECC and OCT were -0.13 and -0.31 μm per year, and 0.04 and 0.61 μm per year. Mean rates of MD change were -0.20 and 0.03 dB per year in patients and controls, respectively (P=0.01). Rates of RNFLT change in glaucoma patients were not statistically different from control subjects for any modality. A significantly negative rate of MD change in patients suggests a genuine, continued deterioration in these patients not reflected by RNFLT changes.