Comparison of scanning laser polarimetry and optical coherence tomography in quantitative retinal nerve fiber assessment

Quantitative analysis of related parameters of retinal nerve fiber layer and ganglion cell complex thickness in patients with different degrees of Parkinson's disease

OBJECTIVE

A quantitative analysis was performed to evaluate the morphologic changes of the retinal nerve fiber layer (RNFL) and macular ganglion cell complex (GCC) in patients with Parkinson's disease (PD).

METHODS

Thirty PD patients were enrolled, and they were allocated to the mild-to-moderate PD group (n = 15) or severe PD group (n = 15) according to the severity of PD. Twenty healthy volunteers (20 eyes) were included as controls. Optical coherence tomography (OCT) was used to measure the thickness of mean RNFL and each of the sectors: temporal-upper (TU), superior-temporal (ST), superior-nasal (SN), nasal-upper (NU), nasal-lower (NL), inferior-nasal (IN), inferior-temporal (IT), temporal-lower (TL). The thickness of macular GCC, superior GCC, and inferior GCC was also measured.

RESULTS

No difference was found between the three groups with respect to age, sex and disease course (p > 0.05). The mean RNFL thickness was 118.15 ± 10.25 µm in the control group, 96.12 ± 9.45 µm in the mild-to-moderate PD group, and 80.48 ± 10.35 µm in the severe PD group. Significant differences were found in the mean RNFL thickness and thickness of TU, IN, IT and TL sectors among the three groups (p < 0.05). These values, mean RNFL, TU, IN, IT, and TL, were lower in both the PD groups than those in the control, among them the severe PD group had the lowest values. A quantitative analysis of the macula GCC was also performed. Overall, there were significant differences in mean macula, superior, and inferior GCC thickness among the three groups (p < 0.05). The two PD groups had lower values of mean macula, superior, and inferior GCC thickness than that in the controls (p < 0.05); and the severe PD group had lowest values of these parameters.

CONCLUSION

In this study, significant thinning of RNFL and macular GCC was found in PD patients. The more serious the illness, the more the thickness becomes thinner. The OCT measurement was found useful in detecting the structural alterations in the retina of PD. The technique may be useful in follow-up of the disease progression after further validation.

Earlier Detection of Glaucoma Progression Using High-Density 3-Dimensional Spectral-Domain OCT Optic Nerve Volume Scans

PURPOSE

To compare onset times of glaucoma progression among different glaucoma tests: disc photography (DP), visual field (VF) testing, 2-dimensional (2D) retinal nerve fiber layer (RNFL) thickness, and 3-dimensional (3D) spectral-domain (SD) OCT neuroretinal rim measurements.

DESIGN

Prospective, longitudinal cohort study.

PARTICIPANTS

One hundred twenty-four eyes of 124 patients with open-angle glaucoma.

METHODS

Over a 5-year period, 124 patients with open-angle glaucoma underwent yearly DP, VF testing, SD OCT RNFL thickness scans, and optic nerve volume scans (Spectralis; Heidelberg Engineering), all performed on the same day. From high-density optic nerve volume scans, custom-built software calculated the minimum distance band (MDB) thickness, a 3D neuroretinal rim parameter. Patients were classified as glaucoma progressors or nonglaucoma progressors using event-based analysis. Progression by DP and VF testing occurred when 3 masked glaucoma specialists unanimously concurred. Progression by RNFL and MDB thickness occurred if change of more than test-retest variability was observed. Kaplan-Meier curves were constructed to analyze time-to-progression data. Kappa Coefficients were used to measure agreement of progressing eyes among methods.

MAIN OUTCOME MEASURES

Time to glaucoma progression among all 4 methods.

RESULTS

Global MDB thickness detected glaucoma progression in the highest percentage of eyes (52.4%) compared with DP (16.1%; P < 0.001) and global RNFL thickness (15.3%; P < 0.001). Global MDB thickness detected glaucoma progression earlier than either DP (23 months vs. 44 months; P < 0.001) or global RNFL thickness (23 months vs. 33 months; P < 0.001). Among MDB progressing eyes, 46.2% were confirmed simultaneously or later by other conventional methods. Agreement of glaucoma-progressing eyes for all 4 methods in paired fashion were slight to fair (κ = 0.095-0.300).

CONCLUSIONS

High-density 3D SD OCT neuroretinal rim measurements detected glaucoma progression approximately 1 to 2 years earlier compared with current clinically available structural tests (i.e., DP and 2D RNFL thickness measurements).

Retinal nerve fibre layer thickness measurements in childhood glaucoma: the role of scanning laser polarimetry and optical coherence tomography

Purpose

A central diagnostic tool in adult glaucoma is the peripapillary retinal nerve fibre layer (pRNFL) thickness. It can be assessed by scanning laser polarimetry (SLP) or optical coherence tomography (OCT). However, studies investigating the relevance of pRNFL measurements in children are rare. This study aims to compare the glaucoma diagnosing ability of SLP and OCT pRNFL thickness measurements in a paediatric population.

Methods

This retrospective study included 105 children (glaucoma: 22 (21.0%); healthy glaucoma suspects: 83 (79.0%)) aged 4–18 years, examined with SLP (GDxPro/ECC, Carl Zeiss Meditec) and spectral-domain OCT (SPECTRALIS®, Heidelberg Engineering). The thickness of pRNFL sectors was compared between diseased and healthy participants. Areas under the receiver-operating characteristic curves (AUC) and logistic regression results were used to compare the glaucoma discriminative capacity between SLP and OCT measurements.

Results

Using OCT, pRNFL thickness was decreased in the superior, nasal, and inferior quadrants of glaucoma patients compared to healthy controls (P < 0.001, each). With SLP, such a difference was only observed in the inferior quadrant (P = 0.011). A correlation between glaucoma diagnosis and OCT-measured pRNFL thickness was found in all quadrants (P < 0.001) other than the temporal. With SLP, a correlation was found for the total average thickness (P = 0.037) and inferior quadrant (P = 0.0019). Finally, the AUCs of OCT measurements were markedly higher than those of SLP (e.g., inferior quadrant: OCT 0.83, SLP 0.68).

Conclusion

pRNFL thickness measurements using both OCT and SLP, correlate notably with the presence of glaucoma. In general, the diagnostic performance of pRNFL thickness measurements seems higher for OCT than for SLP. Thus, pRNFL thickness measurements could provide important information, complementing conventional clinical and functional parameters in the diagnostic process of paediatric glaucoma.

Optical coherence tomography for glaucoma diagnosis: An evidence based meta-analysis

Purpose

Early detection, monitoring and understanding of changes in the retina are central to the diagnosis of glaucomatous optic neuropathy, and vital to reduce visual loss from this progressive condition. The main objective of this investigation was to compare glaucoma diagnostic accuracy of commercially available optical coherence tomography (OCT) devices (Zeiss Stratus, Zeiss Cirrus, Heidelberg Spectralis and Optovue RTVue, and Topcon 3D-OCT).

Patients

16,104 glaucomatous and 11,543 normal eyes reported in 150 studies.

Methods

Between Jan. 2017 and Feb 2017, MEDLINE^®, EMBASE^®, CINAHL^®, Cochrane Library^®, Web of Science^®, and BIOSIS^® were searched for studies assessing glaucoma diagnostic accuracy of the aforementioned OCT devices. Meta-analysis was performed pooling area under the receiver operating characteristic curve (AUROC) estimates for all devices, stratified by OCT type (RNFL, macula), and area imaged.

Results

150 studies with 16,104 glaucomatous and 11,543 normal control eyes were included. Key findings: AUROC of glaucoma diagnosis for RNFL average for all glaucoma patients was 0.897 (0.887–0.906, n = 16,782 patient eyes), for macula ganglion cell complex (GCC) was 0.885 (0.869–0.901, n = 4841 eyes), for macula ganglion cell inner plexiform layer (GCIPL) was 0.858 (0.835–0.880, n = 4211 eyes), and for total macular thickness was 0.795 (0.754–0.834, n = 1063 eyes).

Conclusion

The classification capability was similar across all 5 OCT devices. More diagnostically favorable AUROCs were demonstrated in patients with increased glaucoma severity. Diagnostic accuracy of RNFL and segmented macular regions (GCIPL, GCC) scans were similar and higher than total macular thickness. This study provides a synthesis of contemporary evidence with features of robust inclusion criteria and large sample size. These findings may provide guidance to clinicians when navigating this rapidly evolving diagnostic area characterized by numerous options.

Assessment of the retinal nerve fiber layer in individuals with obstructive sleep apnea

Background

The effect of obstructive sleep apnea (OSA) syndrome in the peripapillary retinal nerve fiber layer (RNFL) thicknesses remains unclear. The purpose of this study was to assess RNFL measurements acquired using scanning laser polarimetry (SLP) and optical coherence tomography (OCT) in patients with OSA.

Methods

The sample of this cross-sectional study included 40 OSA patients and 45 age-matched controls, consecutively and prospectively selected. All participants underwent at least one reliable standard automated perimetry (SAP) test, while RNFL measurements were obtained using the SLP and OCT. The OSA group was divided into 3 sub-groups based on the apnea/hypopnea index (AHI): mild, moderate, or severe OSA. SAP, SLP, and OCT outcomes were compared between the control and OSA groups. The relationship between AHI and RNFL parameters was also evaluated.

Results

Age was not different between both groups. Mean deviation of SAP was −0.47 ± 0.9 dB and −1.43 ± 2.3 dB in the control and OSA groups, respectively (p = 0.01). RNFL thickness measured with OCT was similar between groups. OSA patients showed increased nerve fiber indicator (NFI; 20.9 ± 7.9 versus 16.42 ± 7.82; p = 0.01) and decreased superior average (59.74 ± 10.35 versus 63.73 ± 6.58; p = 0.03) obtained with SLP compared with healthy individuals. In the total sample, NFI and AHI were moderately correlated (r = 0.358; p = 0.001). In severe OSA subjects (n = 22), NFI and AHI had a Spearman correlation coefficient of 0.44 (p = 0.04).

Conclusion

RNFL thickness measured with OCT did not differ significantly between groups. Severe OSA was related to a reduction of the RNFL thickness assessed by SLP.

Optic nerve head and fibre layer imaging for diagnosing glaucoma

BACKGROUND

The diagnosis of glaucoma is traditionally based on the finding of optic nerve head (ONH) damage assessed subjectively by ophthalmoscopy or photography or by corresponding damage to the visual field assessed by automated perimetry, or both. Diagnostic assessments are usually required when ophthalmologists or primary eye care professionals find elevated intraocular pressure (IOP) or a suspect appearance of the ONH. Imaging tests such as confocal scanning laser ophthalmoscopy (HRT), optical coherence tomography (OCT) and scanning laser polarimetry (SLP, as used by the GDx instrument), provide an objective measure of the structural changes of retinal nerve fibre layer (RNFL) thickness and ONH parameters occurring in glaucoma.

OBJECTIVES

To determine the diagnostic accuracy of HRT, OCT and GDx for diagnosing manifest glaucoma by detecting ONH and RNFL damage.

SEARCH METHODS

We searched several databases for this review. The most recent searches were on 19 February 2015.

SELECTION CRITERIA

We included prospective and retrospective cohort studies and case-control studies that evaluated the accuracy of OCT, HRT or the GDx for diagnosing glaucoma. We excluded population-based screening studies, since we planned to consider studies on self-referred people or participants in whom a risk factor for glaucoma had already been identified in primary care, such as elevated IOP or a family history of glaucoma. We only considered recent commercial versions of the tests: spectral domain OCT, HRT III and GDx VCC or ECC.

DATA COLLECTION AND ANALYSIS

We adopted standard Cochrane methods. We fitted a hierarchical summary ROC (HSROC) model using the METADAS macro in SAS software. After studies were selected, we decided to use 2 x 2 data at 0.95 specificity or closer in meta-analyses, since this was the most commonly-reported level.

MAIN RESULTS

We included 106 studies in this review, which analysed 16,260 eyes (8353 cases, 7907 controls) in total. Forty studies (5574 participants) assessed GDx, 18 studies (3550 participants) HRT, and 63 (9390 participants) OCT, with 12 of these studies comparing two or three tests. Regarding study quality, a case-control design in 103 studies raised concerns as it can overestimate accuracy and reduce the applicability of the results to daily practice. Twenty-four studies were sponsored by the manufacturer, and in 15 the potential conflict of interest was unclear.Comparisons made within each test were more reliable than those between tests, as they were mostly based on direct comparisons within each study.The Nerve Fibre Indicator yielded the highest accuracy (estimate, 95% confidence interval (CI)) among GDx parameters (sensitivity: 0.67, 0.55 to 0.77; specificity: 0.94, 0.92 to 0.95). For HRT measures, the Vertical Cup/Disc (C/D) ratio (sensitivity: 0.72, 0.60 to 0.68; specificity: 0.94, 0.92 to 0.95) was no different from other parameters. With OCT, the accuracy of average RNFL retinal thickness was similar to the inferior sector (0.72, 0.65 to 0.77; specificity: 0.93, 0.92 to 0.95) and, in different studies, to the vertical C/D ratio.Comparing the parameters with the highest diagnostic odds ratio (DOR) for each device in a single HSROC model, the performance of GDx, HRT and OCT was remarkably similar. At a sensitivity of 0.70 and a high specificity close to 0.95 as in most of these studies, in 1000 people referred by primary eye care, of whom 200 have manifest glaucoma, such as in those who have already undergone some functional or anatomic testing by optometrists, the best measures of GDx, HRT and OCT would miss about 60 cases out of the 200 patients with glaucoma, and would incorrectly refer 50 out of 800 patients without glaucoma. If prevalence were 5%, e.g. such as in people referred only because of family history of glaucoma, the corresponding figures would be 15 patients missed out of 50 with manifest glaucoma, avoiding referral of about 890 out of 950 non-glaucomatous people.Heterogeneity investigations found that sensitivity estimate was higher for studies with more severe glaucoma, expressed as worse average mean deviation (MD): 0.79 (0.74 to 0.83) for MD < -6 db versus 0.64 (0.60 to 0.69) for MD ≥ -6 db, at a similar summary specificity (0.93, 95% CI 0.92 to 0.94 and, respectively, 0.94; 95% CI 0.93 to 0.95; P < 0.0001 for the difference in relative DOR).

AUTHORS' CONCLUSIONS

The accuracy of imaging tests for detecting manifest glaucoma was variable across studies, but overall similar for different devices. Accuracy may have been overestimated due to the case-control design, which is a serious limitation of the current evidence base.We recommend that further diagnostic accuracy studies are carried out on patients selected consecutively at a defined step of the clinical pathway, providing a description of risk factors leading to referral and bearing in mind the consequences of false positives and false negatives in the setting in which the diagnostic question is made. Future research should report accuracy for each threshold of these continuous measures, or publish raw data.

Morphological characteristics of the optic nerve evaluated by confocal laser tomography (HRT3) and laser polarimetry (GDx-VCC) in a normal population from the city of Barcelona

OBJECTIVE

To evaluate morphological parameters of optic disc and retinal nerve fiber layer (RNFL) examined with confocal laser tomography (HRT3) and laser polarimetry (GDx-VCC) in a normal population, and analyze correlations of these parameters with demographic variables.

PATIENTS AND METHODS

Cross-sectional study in the context of a glaucoma screening campaign in the primary care center of Barcelona. The individuals selected were non-hypertensive Mediterranean Caucasians with risk for glaucoma development (individuals≥60 years old or≥40 years old with family history of glaucoma or intraocular pressure or myopia>3diopter). All subjects underwent a complete ophthalmic examination, confocal laser tomography (HRT3) and scanning laser polarimetry (GDX-VCC), subjects with results within normal limits only being included. Structural parameters were analyzed along with age, refraction, and pachymetry based on the Spearman rank correlation test.

RESULTS

A total of 224 subjects included, with a mean age of 63.4±11.1 years. Disc areas, excavation and ring area were 2.14±0.52mm(2), 0.44±0.34mm (2) and 1.69±0.38mm(2), respectively. The mean RNFL (GDX) was 55.9±6.9μm. Age was correlated with lower ring volume, highest rate of cup shape measure, largest mean and maximum cup depth, lower nerve fiber index (NFI) and RNFL (all p-values below .05).

CONCLUSION

The mean values and distribution of several parameters of the papilla and the RNFL in normal Mediterranean Caucasians population are presented. A loss of thickness of the RNFL, ring thinning, and enlarged cup was observed with increased age.

Comparative study of the retinal nerve fibre layer thickness performed with optical coherence tomography and GDx scanning laser polarimetry in patients with primary open-angle glaucoma

Background

We compared the parameters of retinal nerve fibre layer in patients with advanced glaucoma with the use of different OCT (Optical Coherence Tomograph) devices in relation to analogical measurements performed with GDx VCC (Nerve Fiber Analyzer with Variable Corneal Compensation) scanning laser polarimetry.

Material/Methods

Study subjects had advanced primary open-angle glaucoma, previously treated conservatively, diagnosed and confirmed by additional examinations (visual field, ophthalmoscopy of optic nerve, gonioscopy), A total of 10 patients were enrolled (9 women and 1 man), aged 18–70 years of age. Nineteen eyes with advanced glaucomatous neuropathy were examined. 1) Performing a threshold perimetry Octopus, G2 strategy and ophthalmoscopy of optic nerve to confirm the presence of advanced primary open-angle glaucoma; 2) performing a GDx VCC scanning laser polarimetry of retinal nerve fibre layer; 3) measuring the retinal nerve fibre layer thickness with 3 different optical coherence tomographs.

Results

The parameters of the retinal nerve fibre layer thickness are highly correlated between the GDx and OCT Stratus and 3D OCT-1000 devices in mean retinal nerve fibre layer thickness, retinal nerve fibre layer thickness in the upper sector, and correlation of NFI (GDx) with mean retinal nerve fibre layer thickness in OCT examinations. Absolute values of the retinal nerve fibre layer thickness (measured in μm) differ significantly between GDx and all OCT devices.

Conclusions

Examination with OCT devices is a sensitive diagnostic method of glaucoma, with good correlation with the results of GDx scanning laser polarimetry of the patients.

Diagnostic accuracy of nerve fibre layer, macular thickness and optic disc measurements made with the RTVue-100 optical coherence tomograph to detect glaucoma

PURPOSE

To evaluate the diagnostic accuracy of retinal nerve fibre layer thickness (RNFLT), ganglion cell complex (GCC), and optic disc measurements made with the RTVue-100 Fourier-domain optical coherence tomography (OCT) to detect glaucoma in a Caucasian referral population.

METHODS

One randomly selected eye of 286 Caucasian patients (93 healthy, 36 ocular hypertensive, 46 preperimetric glaucoma, and 111 perimetric glaucoma eyes) was evaluated.

RESULTS

Using the software-provided classification, for the total population sensitivity did not exceed 73.6% for the optic nerve head parameters, and 62.7% for the other parameters. Specificity was high (94.6-100%) for most RNFLT and GCC parameters, but low (72.0-76.3%) for the optic disc parameters. Positive predictive value varied between 98.1 and 100% for the main RNFLT parameters, 92.6 and 100% for the 16 RNFLT sectors, 92.4 and 99.0% for the GCC parameters, but did not exceed 86.3% for any of the optic disc parameters. Positive likelihood ratio (PLR) was higher than 10 for average, inferior and superior RNFLT (25.5 to infinite), 12 of the 16 RNFLT sectors (12.6 to infinite), and three of the four GCC parameters (40.0 to 48.6). No optic disc parameter had a PLR higher than 3.0.

CONCLUSIONS

RNFLT and GCC parameters of the RTVue-100 Fourier-domain OCT showed moderate sensitive but high specificity, positive predictive value and PLR for detection of glaucoma. The optic disc parameters had lower diagnostic accuracy than the RNFLT and GCC parameters.

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

Purpose

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.

Methods

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.

Results

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).

Conclusions

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.

Comparison of optical coherence tomography and scanning laser polarimetry measurements in patients with multiple sclerosis

PURPOSE

To compare optical coherence tomography (OCT) and scanning laser polarimetry (GDx) measurements of the retinal nerve fiber layer (RNFL) in multiple sclerosis (MS) patients with and without optic neuritis (ON).

METHODS

OCT and GDx were performed on 68 MS patients. Qualifying eyes were divided into two groups: 51 eyes with an ON history > or =6 months before (ON eyes) and 65 eyes with no history of ON (non-ON eyes). Several GDx and OCT parameters and criteria were used to define an eye as abnormal, for example, GDx nerve fiber indicator (NFI) >20 or 30, OCT average RNFL thickness, and GDx temporal-superior-nasal-inferior-temporal average (TSNIT) below 5 or 1% of the normative database of the instruments. Agreement between OCT and GDx parameters was reported as percent of observed agreement, along with the AC1 statistic. Linear regression analyses were used to examine the relationship between OCT average RNFL thickness and GDx NFI and TSNIT.

RESULTS

All OCT and GDx measurements showed significantly more RNFL damage in ON than in non-ON eyes. Agreement between OCT and GDx parameters ranged from 69 to 90% (AC1 0.37 to 0.81) in ON eyes and 52 to 91% (AC1 = 0.21 to 0.90) in non-ON eyes. Best agreement was observed between OCT average RNFL thickness (p < 0.01) and NFI (>30) in ON eyes (90%, AC1 = 0.81) and between OCT average RNFL thickness (p < 0.01) and GDx TSNIT average (p < 0.01) in non-ON eyes (91%, AC1 = 0.90). In ON eyes, the OCT average RNFL thickness showed good linear correlation with NFI (R = 0.69, p < 0.0001) and TSNIT (R = 0.55, p < 0.0001).

CONCLUSIONS

OCT and GDx show good agreement and can be useful in detecting RNFL loss in MS/ON eyes.