Glaucoma Diagnostic Capability of Global and Regional Measurements of Isolated Ganglion Cell Layer and Inner Plexiform Layer

Diagnostic Performance for Detection of Glaucomatous Structural Damage Using Pixelwise Analysis of Retinal Thickness Measurements

Purpose

To compare the diagnostic accuracy of thickness measurements of individual and combined macular retinal layers to discriminate 188 glaucomatous and 148 glaucoma suspect eyes from 362 healthy control (HC) eyes on a pixel-by-pixel basis.

Methods

For this retrospective study, we manually corrected the segmentations of posterior pole optical coherence tomography (OCT) scans to determine the thickness of the nerve fiber layer (NFL), ganglion cell layer (GCL), inner plexiform layer (IPL), the ganglion cell complex (GCC), and the total neural retina (TR). For each eye, the total number of pixels with thickness values less than the fifth percentile of the HC distribution was used to create a receiver operating characteristic (ROC) curve for each layer and for layer combinations.

Results

Using total abnormal pixel count criteria to discriminate glaucoma from HC eyes, the individual layers with the highest area under the ROC curve (AUC) were the NFL and GCL; IPL performance was significantly lower (P < 0.05). GCC had a significant higher AUC (94.3%) than individual the AUC of the NFL (92.3%) (P = 0.0231) but not higher than AUC of the GCL (93.4%) (P = 0.3487). The highest AUC (95.4%) and sensitivity (85.1%) at 95% specificity was found for the Boolean combination of NFL or GCL. The highest AUC is not significantly higher (P = 0.0882) than the AUC of the GCC but the highest sensitivity is significantly higher than the sensitivity of the GCC. This pattern was similar for discriminating between suspect and HC eyes (P = 0.0356).

Conclusions

Using pixel-based methods, the diagnostic accuracy of NFL and GCL exceeded that of IPL and TR. GCC had equivalent performance as NFL and GCL. The specific spatial locations within the posterior pole that exhibit best performance vary depending on which layer is being assessed. Recognizing this dependency highlights the importance of considering multiple layers independently, as they offer complementary information for effective and comprehensive diagnosis.

Association of Long-Term Intraocular Pressure Variability and Rate of Ganglion Complex Thinning in Patients With Glaucoma

PURPOSE

To evaluate the association of mean intraocular pressure (IOP) and IOP variability (IOP fluctuation [SD of IOP] and the IOP range) with the rate of ganglion cell complex (GCC) layer thinning over time in patients with glaucoma.

DESIGN

Prospective cohort study.

METHODS

Participants with at least 4 visits and 2 years of follow-up of optical coherence tomography tests were included. A linear mixed-effect model was used to investigate the association of IOP parameters with the rates of GCC thinning. Subgroup analyses were conducted for eyes with early (MD ≥ -6 dB), and moderate to advanced stage (MD < -6 dB) at baseline.

RESULTS

The cohort consisted of 369 eyes of 249 glaucoma patients (282 early glaucoma and 87 moderate to advanced glaucoma) with mean (standard deviation [SD]) age of 68.2 (10.7) years over 5.1 years of follow-up. The mean rate of GCC change was -0.59 (95% confidence interval [CI], -0.67 to -0.52) µm per year. In multivariable models, faster annual rate of GCC thinning was associated with a higher IOP fluctuation (-0.17 [95% CI, -0.23 to -0.11] µm per 1-mmHg higher, P < .001) or higher IOP range (-0.07 [95% CI, -0.09 to -0.05] µm per 1-mmHg higher, P < .001) after adjustment for mean IOP and other confounding factors. Similar results were found for early and moderate to advanced stages of glaucoma.

CONCLUSIONS

IOP variability showed an independent association with macular change in patients with glaucoma regardless of severity at baseline, even after adjustment for mean IOP, supporting its potential value as a therapeutic target for clinical decision-making.

Stage specific glaucomatous changes of the macula recorded using spectral domain optical coherence tomography

BACKGROUND

This study aimed to compare the thickness of different macular retinal layers in glaucomatous eyes and healthy controls, and evaluate the diagnostic performance of spectral domain optical coherence tomography (SD-OCT) parameters.

METHODS

In this cross-sectional comparative study, 48 glaucomatous eyes and 44 healthy controls were included. The thickness of the total retina and all retinal layers were obtained using the Early Treatment Diagnostic Retinopathy Study (ETDRS) grid. The minimal and average values of outer and inner ETDRS-rings were calculated. The diagnostic performance for detection of glaucoma was evaluated using the area under the receiver operating characteristic curve (AUC).

RESULTS

The thickness of the total retina, ganglion cell layer (GCL), and inner-plexiform layer (IPL) was significantly thinner in glaucomatous eyes in all sectors except the center (all p<0.05). The thickness of retinal nerve fiber layer (RNFL) was significantly thinner in the glaucoma group except in the center, nasal inner, and temporal outer sectors (all p<0.05). Layer thinning advanced with glaucoma severity. The minimal outer GCL thickness showed the highest AUC value for discrimination between glaucomatous eyes and healthy controls(0.955). The minimal outer IPL showed the highest AUC value for discriminating early-stage glaucomatous eyes from healthy controls (0.938).

CONCLUSIONS

Glaucomatous eyes were found to have significant thinning in the macular region. GCL and IPL showed high ability to discriminate glaucomatous and early-stage glaucomatous eyes from controls. Applying the minimal value to the ETDRS grid has the potential to provide good diagnostic abilities in glaucoma screening.

Association Between Rate of Ganglion Cell Complex Thinning and Rate of Central Visual Field Loss

Importance

Whether rapid ganglion cell complex (GCC) thinning during an initial follow-up period is associated with rates of central visual field loss over time is unclear but important to understand because risk of glaucoma progression can help guide treatment intensity.

Objective

To investigate the association between the rate of GCC thinning during initial follow-up and the rate of central visual field loss.

Design, Setting, and Participants

This retrospective cohort study assessed patients older than 18 years with glaucoma at a tertiary glaucoma center who were followed up from June 18, 2014, to January 11, 2019. Data analysis for the current study was undertaken in March 2022.

Main Outcomes and Measures

Initial rates of GCC thinning were obtained from global GCC thickness values of the first 3 optical coherence tomography (OCT) scans. Rates of central visual field loss were assessed as the change in central (10-2) visual field mean deviation during the 4.7-year follow-up period by univariable and multivariable linear mixed-effects models. Eyes were categorized as slow (>-1 μm/y) or fast (≤-1 μm/y) progressors based on rates of GCC thinning.

Results

The cohort consisted of 202 eyes of 139 patients (mean [SD] age, 68.7 [10.0] years; 72 male [51.8%]); 44 African American patients (31.7%), 13 Asian patients (9.4%), 80 White patients (57.6%), and 2 patients who identified as other race and ethnicity (1.4%) were analyzed. The rate of GCC change was -0.56 μm/y (95% CI, -0.66 to -0.46 μm/y) during a mean initial follow-up of 1.8 years (95% CI, 1.7-2.0 years). A total of 163 eyes (80.7%) were slow OCT progressors, and 39 (19.3%) were fast OCT progressors, with rates of GCC thinning of -0.3 μm/y (95% CI, -0.4 to -0.2 μm/y) and -1.6 μm/y (-1.8 to -1.3 μm/y), respectively. The rates of 10-2 visual field mean deviation worsening among slow and fast OCT progressors were -0.10 dB/y (95% CI, -0.16 to 0.00 dB/y) and -0.34 dB/y (95% CI, -0.51 to -0.16 dB/y), respectively (difference, -0.26 dB/y; 95% CI, -0.45 to -0.07 dB/y; P = .008).

Conclusions and Relevance

In this cohort study, rapid GCC thinning during an initial follow-up period was associated with faster rates of central visual field decline. These findings support use of longitudinal macular OCT scans assisting clinical decision-making for glaucoma and also may guide possible intensification of therapy in high-risk patients.

Comparison of Ganglion Cell Layer and Ganglion Cell/Inner Plexiform Layer Measures for Detection of Early Glaucoma

PURPOSE

To test the hypothesis that macular ganglion cell layer (GCL) measurements detect early glaucoma with higher accuracy than ganglion cell/inner plexiform layer (GCIPL) thickness measurements.

DESIGN

Cross-sectional study.

PARTICIPANTS

The first cohort included 58 glaucomatous eyes with visual field mean deviation (MD) ≥ -6 dB and 125 normal eyes. The second cohort included 72 glaucomatous and 73 normal/glaucoma suspect (GS) eyes with scans able to create GCL/GCIPL deviation maps.

METHODS

In the first cohort, 8 × 8 GCL and GCIPL grids were exported and 5 superior and inferior sectors were defined. Global and sectoral GCL and GCIPL measures were used to predict glaucoma. In the second cohort, proportions of scan areas with abnormal (< 5% and < 1% cutoffs) and supernormal (> 95% and > 99% cutoffs) thicknesses on deviation maps were calculated. The extents of GCL and GCIPL abnormal areas were used to predict glaucoma.

MAIN OUTCOME MEASURES

Extents of abnormal GCL/GCIPL regions and areas under receiver operating characteristic curves (AUROC) for prediction of glaucoma were compared between GCL or GCIPL measures.

RESULTS

The average ± standard deviation MDs were -3.7 ± 1.6 dB and -2.7 ± 1.8 dB in glaucomatous eyes in the first and second cohorts, respectively. Global GCIPL thickness measures (central 18° × 18° macular region) performed better than GCL for early detection of glaucoma (AUROC, 0.928 vs. 0.884, respectively; P = 0.004). Superior and inferior sector 3 thickness measures provided the best discrimination with both GCL and GCIPL (inferior GCL AUROC, 0.860 vs. GCIPL AUROC, 0.916 [P = 0.001]; superior GCL AUROC, 0.916 vs. GCIPL AUROC, 0.900 [P = 0.24]). The extents of abnormal GCL regions at a 1% cutoff in the central elliptical area were 17.5 ± 22.2% and 6.4 ± 10.8% in glaucomatous and normal/GS eyes, respectively, versus 17.0 ± 22.2% and 5.7 ± 10.5%, respectively, for GCIPL (P = 0.06 for GCL and 0.002 for GCIPL). The extents of GCL and GCIPL supernormal regions were mostly similar in glaucomatous and normal eyes. The best performance for prediction of glaucoma in the second cohort was detected at a P value of < 1% within the entire scan for both GCL and GCIPL (AUC, 0.681 vs. 0.668, respectively; P = 0.29).

CONCLUSIONS

Macular GCL and GCIPL thicknesses are equivalent for identifying early glaucoma with current OCT technology. This is likely explained by limitations of inner macular layer segmentation and concurrent changes within the inner plexiform layer in early glaucoma.

Comparison of Ganglion Cell Layer and Inner Plexiform Layer Rates of Change in Suspected and Established Glaucoma

PURPOSE

We compared ganglion cell layer (GCL) and inner plexiform layer (IPL) rates of change (RoC) in patients with glaucoma suspect (GS) and established glaucoma (EG) to test the hypothesis that IPL thickness changes would occur earlier than GCL changes in eyes with early damage.

DESIGN

Prospective, cohort study.

METHODS

A total of 64 GS eyes (46 patients) and 112 EG eyes (112 patients) with ≥2 years of follow-up and ≥3 macular optical coherence tomography scans were included. GCL and IPL superpixel thickness measurements were exported. A Bayesian hierarchical model with random intercepts/slopes and random residual variances was fitted to estimate RoC in individual superpixels. Normalized RoC and proportions of superpixels with significantly negative and positive GCL and IPL RoC were compared within the groups.

RESULTS

The average (SD) follow-up time and number of scans were 3.5 (0.7) years and 4.2 (1.0), respectively, in the GS group and 3.6 (0.4) years and 7.3 (1.1) in the EG group. Mean (SD) normalized RoC was faster for GCL than IPL (-0.69 [0.05] vs -0.33 [0.04]) in the GS group, whereas it was faster for IPL (-0.47 [0.03] vs -0.28 [0.02]) in EG eyes. GCL RoC were significantly negative in 24 of 36 superpixels compared with 8 of 36 for IPL (P < .001) in GS eyes. In the EG group, 23 of 36 superpixels had significant negative IPL RoC compared with 13 of 36 superpixels for GCL (P = .006).

CONCLUSIONS

GCL thickness is more likely to demonstrate change over time compared with IPL in glaucoma suspects. There is no evidence of preferential IPL thinning in eyes with suspected early glaucoma damage.

Multivariate Longitudinal Modeling of Macular Ganglion Cell Complex: Spatiotemporal Correlations and Patterns of Longitudinal Change

Purpose

To investigate spatiotemporal correlations among ganglion cell complex (GCC) superpixel thickness measurements and explore underlying patterns of longitudinal change across the macular region.

Design

Longitudinal cohort study.

Subjects

One hundred eleven eyes from 111 subjects from the Advanced Glaucoma Progression Study with ≥ 4 visits and ≥ 2 years of follow-up.

Methods

We further developed our proposed Bayesian hierarchical model for studying longitudinal GCC thickness changes across macular superpixels in a cohort of glaucoma patients. Global priors were introduced for macular superpixel parameters to combine data across superpixels and better estimate population slopes and intercepts.

Main Outcome Measures

Bayesian residual analysis to inspect cross-superpixel correlations for subject random effects and residuals. Principal component analysis (PCA) to explore underlying patterns of longitudinal macular change.

Results

Average (standard deviation [SD]) follow-up and baseline 10-2 visual field mean deviation were 3.6 (0.4) years and -8.9 (5.9) dB, respectively. Superpixel-level random effects and residuals had the greatest correlations with nearest neighbors; correlations were higher in the superior than in the inferior region and strongest among random intercepts, followed by random slopes, residuals, and residual SDs. PCA of random intercepts showed a first large principal component (PC) across superpixels that approximated a global intercept, a second PC that contrasted the superior and inferior macula, and a third PC, contrasting inner and nasal superpixels with temporal and peripheral superpixels. PCs for slopes, residual SDs, and residuals were remarkably similar to those of random intercepts.

Conclusions

Introduction of cross-superpixel random intercepts and slopes is expected to improve estimation of population and subject parameters. Further model enhancement may be possible by including cross-superpixel random effects and correlations to address spatiotemporal relationships in longitudinal data sets.

Ganglion Cell Complex: The Optimal Measure for Detection of Structural Progression in the Macula

PURPOSE

To test the hypothesis that macular ganglion cell complex (GCC) thickness from optical coherence tomography (OCT) provides a stronger change signal regardless of glaucoma severity compared with other macular measures.

DESIGN

Prospective cohort study.

METHODS

Eyes were from 112 patients with moderate to severe glaucoma at baseline from a tertiary glaucoma center. In each 3° × 3° macular superpixel, a hierarchical Bayesian random intercept and slope model with random residual variance was fit to longitudinal full macular thickness (FMT), outer retina layers, GCC, ganglion cell-inner plexiform layer (GCIPL), and ganglion cell layer (GCL) measurements. We estimated population- and individual-level slopes and intercepts. Proportions of substantial worsening and improving superpixel slopes were compared between layers and in superpixels with mild to moderate vs severe damage (total deviation of corresponding visual field location ≥ -8 vs < -8 dB).

RESULTS

Mean (SD) follow-up time and baseline 10-2 visual field mean deviation were 3.6 (0.4) years and -8.9 (5.9) dB, respectively. FMT displayed the highest proportion of significant negative slopes (1932/3519 [54.9%]), followed by GCC (1286/3519 [36.5%]), outer retina layers (1254/3519 [35.6%]), (GCIPL) (1075/3518 [30.6%]), and (GCL) (698/3518 [19.8%]). Inner macular measures detected less worsening in the severe glaucoma group; yet GCC (223/985 [22.6%]) identified the highest proportion (GCIPL: 183/985 [18.6%]; GCL: 106/985 [10.8%]). Proportions of positive rates were small and comparable among all measures.

CONCLUSIONS

GCC is the optimal macular measure for detection of structural change in eyes with moderate to severe glaucoma. Although a higher proportion of worsening superpixels was observed for FMT, a large portion of FMT change could be attributed to changes in outer retina layers.

Estimating Ganglion Cell Complex Rates of Change With Bayesian Hierarchical Models

Purpose

Develop a hierarchical longitudinal regression model for estimating local rates of change of macular ganglion cell complex (GCC) measurements with optical coherence tomography (OCT).

Methods

We enrolled 112 eyes with four or more macular OCT images and ≥2 years of follow-up. GCC thickness measurements within central 6 × 6 superpixels were extracted from macular volume scans. We fit data from each superpixel separately with several hierarchical Bayesian random-effects models. Models were compared with the Watanabe–Akaike information criterion. For our preferred model, we estimated population and individual slopes and intercepts (baseline thickness) and their correlation.

Results

Mean (SD) follow-up time and median (interquartile range) baseline 24-2 visual field mean deviation were 3.6 (0.4) years and −6.8 (−12.2 to −4.3) dB, respectively. The random intercepts and slopes model with random residual variance was the preferred model. While more individual and population negative slopes were observed in the paracentral and papillomacular superpixels, superpixels in the superotemporal and inferior regions displayed the highest correlation between baseline thickness and rates of change (r = –0.43 to –0.50 for the top five correlations).

Conclusions

A Bayesian linear hierarchical model with random intercepts/slopes and random variances is an optimal initial model for estimating GCC slopes at population and individual levels. This novel model is an efficient method for estimating macular rates of change and probability of glaucoma progression locally.

Translational Relevance

The proposed Bayesian hierarchical model can be applied to various macular outcomes from different OCT devices and to superpixels of variable sizes to estimate local rates of change and progression probability.

Early localized alterations of the retinal inner plexiform layer in association with visual field worsening in glaucoma patients

Glaucoma is a chronic neurodegenerative disease of the optic nerve and a leading cause of irreversible blindness, worldwide. While the experimental research using animal models provides growing information about cellular and molecular processes, parallel analysis of the clinical presentation of glaucoma accelerates the translational progress towards improved understanding, treatment, and clinical testing of glaucoma. Optic nerve axon injury triggers early alterations of retinal ganglion cell (RGC) synapses with function deficits prior to manifest RGC loss in animal models of glaucoma. For testing the clinical relevance of experimental observations, this study analyzed the functional correlation of localized alterations in the inner plexiform layer (IPL), where RGCs establish synaptic connections with retinal bipolar and amacrine cells. Participants of the study included a retrospective cohort of 36 eyes with glaucoma and a control group of 18 non-glaucomatous subjects followed for two-years. The IPL was analyzed on consecutively collected macular SD-OCT scans, and functional correlations with corresponding 10–2 visual field scores were tested using generalized estimating equations (GEE) models. The GEE-estimated rate of decrease in IPL thickness (R = 0.36, P<0.001) and IPL density (R = 0.36, P<0.001), as opposed to unchanged or increased IPL thickness or density, was significantly associated with visual field worsening at corresponding analysis locations. Based on multivariate logistic regression analysis, this association was independent from the patients’ age, the baseline visual field scores, or the baseline thickness or alterations of retinal nerve fiber or RGC layers (P>0.05). These findings support early localized IPL alterations in correlation with progressing visual field defects in glaucomatous eyes. Considering the experimental data, glaucoma-related increase in IPL thickness/density might reflect dendritic remodeling, mitochondrial redistribution, and glial responses for synapse maintenance, but decreased IPL thickness/density might correspond to dendrite atrophy. The bridging of experimental data with clinical findings encourages further research along the translational path.

Macular imaging with optical coherence tomography in glaucoma

With the advent of spectral-domain optical coherence tomography, imaging of the posterior segment of the eye can be carried out rapidly at multiple anatomical locations, including the optic nerve head, circumpapillary retinal nerve fiber layer, and macula. There is now ample evidence to support the role of spectral-domain optical coherence tomography imaging of the macula for detection of early glaucoma. Macular spectral-domain optical coherence tomography measurements demonstrate high reproducibility, and evidence on its utility for detection of glaucoma progression is accumulating. We present a comprehensive review of macular spectral-domain optical coherence tomography imaging emerging as an essential diagnostic tool in glaucoma.

Discovery and clinical translation of novel glaucoma biomarkers

Glaucoma and other optic neuropathies are characterized by progressive dysfunction and loss of retinal ganglion cells and their axons. Given the high prevalence of glaucoma-related blindness and the availability of treatment options, improving the diagnosis and precise monitoring of progression in these conditions is paramount. Here we review recent progress in the development of novel biomarkers for glaucoma in the context of disease pathophysiology and we propose future steps for the field, including integration of exploratory biomarker outcomes into prospective therapeutic trials. We anticipate that, when validated, some of the novel glaucoma biomarkers discussed here will prove useful for clinical diagnosis and prediction of progression, as well as monitoring of clinical responses to standard and investigational therapies.

Comparison of Rates of Progression of Macular OCT Measures in Glaucoma

Purpose

The purpose of this study was to compare rates of change of various macular thickness measures and evaluate the influence of baseline damage on macular rates of change.

Methods

One hundred twelve eyes (112 patients) with ≥ 2 years of follow-up and ≥ 5 macular optical coherence tomography (OCT) images and 10-2 visual field (VF) tests were included. OCT measures of interests were full macular thickness (FMT), ganglion cell complex (GCC), ganglion cell/inner plexiform layer (GCIPL), ganglion cell layer (GCL), and outer retinal layer (ORL) thickness in 3° × 3° superpixels. Rates of change were estimated with linear regression and normalized by dividing rates by the average normative superpixel thickness. We compared rates of change and proportion of significantly worsening superpixels (detection rate) and improving superpixels (false discovery rate [FDR]) among macular measures as a function of baseline thickness and 10-2 VF status.

Results

Median (interquartile range [IQR]) baseline VF mean deviation, follow-up time, and number of VFs/OCTs were -7.6 dB (-11.8 to -3.8 dB), 4.5 years (4.0-5.0 years), and 9 (8-10), respectively. Normalized FMT and GCC rates of change were faster and detection rates were higher than GCIPL and GCL (P < 0.001), but FMT had lower FDR than GCC (P = 0.02); faster FMT rates were partially explained by ORL rates of change. GCC detection rates were less likely than GCIPL and GCL rates to decrease with diminishing baseline thickness or worse VF damage. In eyes with 10-2 VF worsening, GCC and GCL demonstrated the fastest rates of change.

Conclusions

GCC measurements are most likely to detect structural worsening along the spectrum of glaucoma severity. Although FMT rates of change are least influenced by baseline thickness, they partially reflect likely age-related ORL changes.

Translational Relevance

GCC thickness measurements seem to be the optimal macular outcome measure for detection of glaucoma deterioration.

Relationship of the Macular Ganglion Cell and Inner Plexiform Layers in Healthy and Glaucoma Eyes

Purpose

To explore factors influencing the inner plexiform layer (IPL) in healthy subjects and to test the hypothesis that IPL thickness is preferentially decreased in glaucoma as compared with ganglion cell layer (GCL) thickness.

Methods

Ninety-nine glaucomatous eyes and 66 healthy eyes (165 subjects) underwent macular spectral-domain optical coherence tomography (SD-OCT) imaging and GCL and IPL were segmented creating 8 × 8 arrays of 3° × 3° superpixels. The central 24 superpixels were categorized into three levels of eccentricity (∼1.5°, 4.5°, and 7.5° from the foveal center). Linear mixed models were used to determine predictive parameters for IPL thickness in healthy subjects and to explore the influence of diagnosis of glaucoma on IPL thickness taking into account the effect of GCL thickness and other covariates.

Results

Being located at 4.5° eccentricity predicted thicker IPL compared with 1.5° eccentricity (P < 0.001) in multivariable models in healthy subjects, whereas older age (P = 0.001) and Asian ethnicity (P = 0.021) were associated with thinner IPL. Diagnosis of glaucoma was not associated with thinner IPL regardless of eccentricity after accounting for age and ethnicity. The results were similar when only eyes with mean deviation greater than –6 dB were analyzed.

Conclusions

Ethnicity and distance from the fovea are the main determinants of IPL thickness in the central macula. Preferential thinning of the macular IPL, compared with GCL, could not be detected in this study regardless of glaucoma stage.

Translational Relevance

There is no evidence for preferential thinning of the macular IPL in glaucoma compared with GCL based on currently available SD-OCT–imaging technology.

Comparison of Associations with Different Macular Inner Retinal Thickness Parameters in a Large Cohort: The UK Biobank

PURPOSE

To describe and compare associations with macular retinal nerve fiber layer (mRNFL), ganglion cell complex (GCC), and ganglion cell-inner plexiform layer (GCIPL) thicknesses in a large cohort.

DESIGN

Cross-sectional study.

PARTICIPANTS

We included 42 044 participants in the UK Biobank. The mean age was 56 years.

METHODS

Spectral-domain OCT macular images were segmented and analyzed. Corneal-compensated intraocular pressure (IOPcc) was measured with the Ocular Response Analyzer (Reichert, Corp., Buffalo, NY). Multivariable linear regression was used to examine associations with mean mRNFL, GCC, and GCIPL thicknesses. Factors examined were age, sex, ethnicity, height, body mass index (BMI), smoking status, alcohol intake, Townsend deprivation index, education level, diabetes status, spherical equivalent, and IOPcc.

MAIN OUTCOME MEASURES

Thicknesses of mRNFL, GCC, and GCIPL.

RESULTS

We identified several novel independent associations with thinner inner retinal thickness. Thinner inner retina was associated with alcohol intake (most significant for GCIPL: -0.46 μm for daily or almost daily intake compared with special occasion only or never [95% confidence interval (CI), 0.61-0.30]; P = 1.1×10^-8), greater social deprivation (most significant for GCIPL: -0.28 μm for most deprived quartile compared with least deprived quartile [95% CI, -0.42 to -0.14]; P = 6.6×10^-5), lower educational attainment (most significant for mRNFL: -0.36 μm for less than O level compared with degree level [95% CI, -0.45 to 0.26]; P = 2.3×10^-14), and nonwhite ethnicity (most significant for mRNFL comparing blacks with whites: -1.65 μm [95% CI, -1.86 to -1.43]; P = 2.4×10^-50). Corneal-compensated intraocular pressure was associated most significantly with GCIPL (-0.04 μm/mmHg [95% CI, -0.05 to -0.03]; P = 4.0×10^-10) and was not associated significantly with mRNFL (0.00 μm/mmHg [95% CI, -0.01 to 0.01]; P = 0.77). The variables examined explained a greater proportion of the variance of GCIPL (11%) than GCC (6%) or mRNFL (7%).

CONCLUSIONS

The novel associations we identified may be important to consider when using inner retinal parameters as a diagnostic tool. Associations generally were strongest with GCIPL, particularly for IOP. This suggests that GCIPL may be the superior inner retinal biomarker for macular pathophysiologic processes and especially for glaucoma.

Inner macular layer thickness by spectral domain optical coherence tomography in children and adults: a hospital-based study

Purpose

To establish the normative ranges of macular ganglion cell layer (mGCL) and macular inner plexiform layer (mIPL) thickness using Spectralis spectral domain optical coherence tomography (SD-OCT) (Heidelberg Engineering, Inc., Heidelberg, Germany) in both Korean children and adults, and to determine factors associated with mGCL and mIPL thickness.

Methods

We conducted a retrospective, observational study of 573 healthy subjects (5–70 years old) who underwent comprehensive ophthalmic examinations in a single institution. Each inner retinal layer thickness was measured using SD-OCT and automatic segmentation software. Cross-sectional analysis was used to evaluate the effect of gender, age and ocular parameters on mGCL and mIPL thickness. Normative ranges of mGCL and mIPL thickness according to age, gender and factors associated with mGCL and mIPL thickness were measured.

Results

The mean mGCL and mIPL thickness were 40.6±2.8 and 33.8±2.0 µm, respectively. Determinants of inner sector mGCL thickness were circumpapillary retinal nerve fibre layer (cpRNFL) thickness (β=1.172, p<0.001), age (β=−0.019, p=0.021) and male gender (β=1.452, p<0.001). Determinants of inner sector mIPL thickness were cpRNFL (β=0.952, p<0.001) and male gender (β=1.163, p<0.001). The inner sector mGCL and mIPL thickness increased significantly with age in children (β=0.174, p=0.009 and β=0.115, p=0.013), and then decreased in adults (β=−0.070, p<0.001 and β=−0.024, p=0.032). In the case of outer sectors, mGCL and mIPL thickness were not significantly related to age and gender.

Conclusions

This study ensured a normative range of the mGCL and mIPL thickness using Spectralis OCT. Gender, age and cpRNFL thickness significantly correlated with mGCL and mIPL thickness. This information should be considered in the interpretation of SD-OCT data.

Analysis of peripapillary retinal nerve fiber layer and inner macular layers by spectral-domain optical coherence tomography for detection of early glaucoma

AIM

To analyze the diagnostic capabilities of peripapillary retinal nerve fiber layer (pRNFL) thickness and segmented inner macular layer (IML) thickness measured by spectral-domain optical coherence tomography for detection of early glaucoma.

METHODS

Fifty-three patients with primary open angle glaucoma (POAG), 60 patients with normal tension glaucoma (NTG) and 32 normal control subjects were enrolled. Thicknesses of pRNFL, total macular layers (TML), and the IML, including macular RNFL (mRNFL) and macular ganglion cell layer (mGCL) were assessed. The areas under the receiver operating characteristic curves (AROC) were calculated to compare the diagnostic power of different parameters.

RESULTS

There were no differences in the parameters of pRNFL, TML, and IML between POAG and NTG groups. The thicknesses of superior and inferior mGCL showed significant correlation with mean deviation of visual field (R²=0.071, P=0.004; R²=0.08, P=0.002). The mGCL thickness significantly correlated with the pRNFL thickness in the superior and inferior quadrants (R²=0.156, P<0.001; R²=0.407, P<0.001). The thickness of the inferior-outer sector of macula had greater AROCs than those in the inferior-inner sector of macula. The AROCs for superior (0.894) and inferior (0.879) pRNFL thicknesses were similar with the AROCs for superior (0.839) and inferior mGCL (0.864) thicknesses. Sensitivities at 80% specificity for global pRNFL, inferior-outer mGCL and inferior-outer mRNFL thicknesses were 0.938, 0.867, and 0.725, respectively.

CONCLUSION

The diagnostic capability of the mGCL thickness is comparable to that of the pRNFL thickness in patients with early glaucoma. The inferior-outer sector of IML has a better diagnostic capability than the inferior-inner sector of IML for detection of early glaucoma.

New Normative Database of Inner Macular Layer Thickness Measured by Spectralis OCT Used as Reference Standard for Glaucoma Detection

Purpose

This study examines the capacity to detect glaucoma of inner macular layer thickness measured by spectral-domain optical coherence tomography (SD-OCT) using a new normative database as the reference standard.

Methods

Participants (N = 148) were recruited from Leuven (Belgium) and Zaragoza (Spain): 74 patients with early/moderate glaucoma and 74 age-matched healthy controls. One eye was randomly selected for a macular scan using the Spectralis SD-OCT. The variables measured with the instrument's segmentation software were: macular nerve fiber layer (mRNFL), ganglion cell layer (GCL), and inner plexiform layer (IPL) volume and thickness along with circumpapillary RNFL thickness (cpRNFL). The new normative database of macular variables was used to define the cutoff of normality as the fifth percentile by age group. Sensitivity, specificity, and area under the receiver operating characteristic curve (AUROC) of each macular measurement and of cpRNFL were used to distinguish between patients and controls.

Results

Overall sensitivity and specificity to detect early-moderate glaucoma were 42.2% and 88.9% for mRNFL, 42.4% and 95.6% for GCL, 42.2% and 94.5% for IPL, and 53% and 94.6% for RNFL, respectively. The best macular variable to discriminate between the two groups of subjects was outer temporal GCL thickness as indicated by an AUROC of 0.903. This variable performed similarly to mean cpRNFL thickness (AUROC = 0.845; P = 0.29).

Conclusions

Using our normative database as reference, the diagnostic power of inner macular layer thickness proved comparable to that of peripapillary RNFL thickness.

Translational Relevance

Spectralis SD-OCT, cpRNFL thickness, and individual macular inner layer thicknesses show comparable diagnostic capacity for glaucoma and RNFL, GCL, and IPL thickness may be useful as an alternative diagnostic test when the measure of cpRNFL shows artifacts.

A new strategy to interpret OCT posterior pole asymmetry analysis for glaucoma diagnosis

AIM

To detect early glaucoma by optical coherence tomography (OCT) posterior pole asymmetry analysis.

METHODS

Totally 39 eyes from 39 healthy subjects, 40 eyes from 40 mild glaucoma patients, 33 eyes from 33 moderate glaucoma patients and 41 eyes from severe glaucoma patients were included in this study. All subjects underwent posterior pole asymmetry analysis (PPAA) of OCT and the posterior pole area was divided into three zones. Means, standard deviations and 95% confidence intervals of each zone asymmetry in control group were assessed. Retina thickness asymmetry (RTA) of different stage of glaucoma were compared for each zone, and receiver operating characteristic (ROC) curves were made to test the efficacy of strategies using different zones to discriminate glaucomatous eyes from the healthy ones.

RESULTS

In a healthy population, RTA of the centre zone showed the minimal mean value (3.085 µm), standard deviation (1.756), and the narrowest 95% confidence interval (from 2.360 to 3.810 µm). It was only in the center zone that RTA exhibited significant difference between control and moderate glaucoma group (P<0.01), as well as control and severe glaucoma group (P<0.00001). The strategy utilized in the center zone had the strongest diagnostic capability (zone 3 AUROC=0.816, P=0.0016) in comparison to that of the periphery area (zone 1 AUROC=0.675, P=0.0016; zone 2 AUROC=0.623, P=0.0197), the whole posterior pole involved interpreting strategy showed inferior diagnostic power than the centre zone dependent strategy (z=2.851, P=0.0044).

CONCLUSION

Utilizing the posterior pole centre zone to interpret OCT PPAA results are more effective than making use of the whole posterior pole map.