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

Determining relative thickness of inner retinal layers on single-line foveal optical coherence tomography (OCT) in healthy pediatric eyes-normative data for handheld OCT

BACKGROUND

Handheld optical coherence tomography (HH-OCT) lacks integrated segmentation/analysis software. Optic neuropathies cause ganglion cell layer (GCL) thinning, with normal to thickened inner nuclear layer (INL), suggesting the potential value of estimating the GCL/INL ratio on single-line foveal HH-OCT scans. This study determines this ratio in macular scans from healthy eyes of young children using HH-OCT and overhead-mounted OCT.

METHODS

Macular OCT scans were obtained using either HH-OCT or overhead-mounted Spectralis FLEX-OCT in children ages 0-5 years undergoing clinically indicated anesthesia/sedation. Exclusion criteria included gestational age <37 weeks, neurologic disease, amblyopia, ocular disease, or large refractive error (spherical equivalent beyond -3.00 D to +8.00 D). For HH-OCT, the GCL and INL were manually measured in pixels from single-line macular scans at the thickest point nasal and temporal to the fovea. For FLEX-OCT images, measurements were aided by automated software.

RESULTS

HH-OCT was obtained on 38 eyes (38 children, mean age 2.4 ± 1.8 years) and FLEX-OCT on 56 eyes (56 children, mean age 2.3 ± 1.5 years). Mean nasal GCL/INL was 1.24 ± 0.18 (min/max = 0.92/1.75) for HH-OCT and 1.29 ± 0.18 (min/max = 0.96/1.66) for FLEX-OCT (P = 0.11). Mean temporal GCL/INL was 1.22 ± 0.24 (min/max = 0.66/1.70) for HH-OCT and 1.19 ± 0.16 (min/max = 0.86/1.47) for FLEX-OCT (P = 0.47).

CONCLUSIONS

Mean normative GCL/INL ratios were approximately 1.2 at the thickest macular areas both nasal and temporal to the fovea, with either HH-OCT or FLEX-OCT in young children's eyes. These values may prove useful when HH-OCT is used to assess optic neuropathies, in which the GCL/INL ratio is expected to be decreased.

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.

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.

Modelling normal age-related changes in individual retinal layers using location-specific OCT analysis

Current descriptions of retinal thickness across normal age cohorts are mostly limited to global analyses, thus overlooking spatial variation across the retina and limiting spatial analyses of retinal and optic nerve disease. This retrospective cross-sectional study uses location-specific cluster analysis of 8 × 8 macular average grid-wise thicknesses to quantify topographical patterns and rates of normal, age-related changes in all individual retinal layers of 253 eyes of 253 participants across various age cohorts (n = 23-69 eyes per decade). Most retinal layers had concentric spatial cluster patterns except the retinal nerve fibre layer (RNFL) which displayed a nasal, asymmetric radial pattern. Age-related thickness decline mostly occurred after the late 4th decade, described by quadratic regression models. The ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), and outer nuclear layer + Henle's fibre layer (ONL_+HFL) were significantly associated with age (p < 0.0001 to < 0.05), demonstrating similar rates of thickness decline (mean pooled slope =  - 0.07 µm/year), while the IS/OS had lesser mean pooled thickness slopes for all clusters (- 0.04 µm/year). The RNFL, OPL, and RPE exhibited no significant age-related thickness change, and the RNFL were significantly associated with sex. Analysis using spatial clusters compared to the ETDRS sectors revealed more extensive spatial definition and less variability in the former method. These spatially defined, clustered normative data and age-correction functions provide an accessible method of retinal thickness analysis with more spatial detail and less variability than the ETDRS sectors, potentially aiding the diagnosis and monitoring of retinal and optic nerve disease.

Segmenting OCT for detecting drug efficacy in CRAO

PURPOSE

Thinning of the inner layers of the retina occurs in patients with central retinal artery occlusion (CRAO). The mechanism for such thinning may be partially due to proteolysis by a calcium-activated protease called calpain. Calpain inhibitor SNJ-1945 ameliorated the proteolysis in a past series of model experiments. The purposes of the present retrospective study were to: 1) use segmentation analysis of optical coherence tomography (OCT) images to mathematically model the loss of specific retinal layers in CRAO patients, and 2) predict the number of patients and days of observation needed for clinical trials of inhibitors against CRAO.

METHODS

A retrospective case control study was conducted by computer-aided search for CRAO (ICD10 H43.1) with at least one OCT procedure (CPT: 92134) in the OHSU Epic patient data base.

RESULTS

After initial swelling, thinning of the inner retinal layers, especially the ganglion cell (GCL) layer followed exponential decay curves. Using sample size statistics and GCL thickness as a marker in a 30-day clinical trial, 19 eyes/group could theoretically detect a 20% beneficial effect of an inhibitor against CRAO. Other markers, such as the whole retinal thickness and combined inner layers could also be used as less-specific markers.

CONCLUSIONS

Using thickness changes in the GCL layer to monitor the efficacy of potential inhibitors against CRAO is practical in human trials requiring a reasonable number of patients and relatively short trial period.

TRANSLATIONAL RELEVANCE

Measurement of GCL thickness would be a useful indicator of CRAO progression in a clinical trial of putative inhibitors.

Retinal biomarkers for Alzheimer's disease and vascular cognitive impairment and dementia (VCID): implication for early diagnosis and prognosis

Cognitive impairment and dementia are major medical, social, and economic public health issues worldwide with significant implications for life quality in older adults. The leading causes are Alzheimer's disease (AD) and vascular cognitive impairment/dementia (VCID). In both conditions, pathological alterations of the cerebral microcirculation play a critical pathogenic role. Currently, the main pathological biomarkers of AD-β-amyloid peptide and hyperphosphorylated tau proteins-are detected either through cerebrospinal fluid (CSF) or PET examination. Nevertheless, given that they are invasive and expensive procedures, their availability is limited. Being part of the central nervous system, the retina offers a unique and easy method to study both neurodegenerative disorders and cerebral small vessel diseases in vivo. Over the past few decades, a number of novel approaches in retinal imaging have been developed that may allow physicians and researchers to gain insights into the genesis and progression of cerebromicrovascular pathologies. Optical coherence tomography (OCT), OCT angiography, fundus photography, and dynamic vessel analyzer (DVA) are new imaging methods providing quantitative assessment of retinal structural and vascular indicators-such as thickness of the inner retinal layers, retinal vessel density, foveal avascular zone area, tortuosity and fractal dimension of retinal vessels, and microvascular dysfunction-for cognitive impairment and dementia. Should further studies need to be conducted, these retinal alterations may prove to be useful biomarkers for screening and monitoring dementia progression in clinical routine. In this review, we seek to highlight recent findings and current knowledge regarding the application of retinal biomarkers in dementia assessment.

Interdigitation and Ellipsoid Zones Disruption Correlate with Visual Outcomes among Treatment-Naive Patients with Diabetic Macular Edema

INTRODUCTION

We have recently shown that defects in interdigitation and ellipsoid zones (IZ and EZ) can predict response to anti-VEGF therapy in a small group of treatment-naive diabetic macular edema (DME) patients. The aim of the current study is to further evaluate this association in a larger study group of patients over a longer follow-up time.

METHODS

Thirty eyes of 30 treatment-naive DME patients were analyzed in this retrospective study. The integrity of foveal IZ and EZ was evaluated using optical coherence tomography at the diagnosis of DME and following anti-VEGF injections. The defect size was correlated with best-corrected visual acuity (BCVA) and central macular thickness (CMT).

RESULTS

The mean patients' age at baseline was 63.0 ± 10.0 years. Patients underwent 3.9 ± 2.9 anti-VEGF injections for a mean of 9.1 ± 4.8 months. Following treatment, the mean Snellen visual acuity (VA) improved from 20/52 to 20/44 (p = 0.05), CMT decreased from 432.5 ± 141.4 μm to 375.2 ± 121.4 µm (p = 0.05) and IZ/EZ defect size decreased from 259.83 ± 375.94 µm to 65.34 ± 143.97 µm (p = 0.001). In patients with no IZ/EZ defects at baseline, the mean Snellen VA was better when compared to those with IZ/EZ defects (20/36 vs. 20/70, p = 0.031). The number of eyes with IZ/EZ defects decreased from 17 (57%) at baseline to 6 (20%) at end of follow-up (p < 0.01). BCVA gain correlated with IZ/EZ defect size reduction (r = 0.41, p = 0.02) but not with improvement in CMT (r = 0.28, p = 0.121).

CONCLUSIONS

IZ/EZ defect size correlated not only with baseline BCVA but also predicted the change in BCVA after anti-VEGF treatment. Possible future automatic measurement of IZ/EZ defect size might prove helpful for the evaluation of treatment response.

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.

Macular Ganglion Cell-Inner Plexiform Layer, Ganglion Cell Complex, and Outer Retinal Layer Thicknesses in a Large Cohort of Chinese Children

Purpose

The purpose of this study was to describe the normative values, distribution patterns, and correlated factors of macular ganglion cell-inner plexiform layer (GCIPL), ganglion cell complex (GCC), and outer retinal layer (ORL) thicknesses in Chinese children.

Methods

A sample of 3000 healthy children with different refractive status aged 6 to 19 years was consecutively examined. Demographics were recorded, and a comprehensive ophthalmic examination including refractive error and axial length (AL) was taken from all participants. The GCIPL, GCC, and ORL thicknesses were measured using swept source-optical coherence tomography (OCT), and multiple linear regression was used to determine which factors were associated with the thickness of each layer.

Results

The average thickness was 77.00 ± 4.78 μm (95% confidence interval [CI]: 69.56-84.56 μm) in the GCIPL, 107.68 ± 5.95 μm (95% CI: 98.45-117.21 μm) in the GCC, and 178.57 ± 9.02 μm (95% CI: 164.33-192.56 μm) in the ORL. Multiple regression analysis indicated that GCIPL thickness was associated with sex (β = 0.168, P < 0.001), age (β = 0.126, P < 0.001), axial length (β = -0.181, P < 0.001), and refractive error (β = 0.233, P < 0.001). Age (β = 0.154, P < 0.001), sex (β = 0.102, P < 0.001), and refractive error (β = 0.149, P < 0.001) were associated independently with GCC thickness after adjusting for the other factors. Furthermore, age (β = 0.100, P < 0.001), sex (β = 0.163, P < 0.001), AL (β = -0.283, P < 0.001), and refractive error (β = 0.207, P < 0.001) were the independent factors associated with ORL thickness.

Conclusions

The present study established a normative pediatric database for macular layer thicknesses in healthy Chinese children, advancing the ability of OCT in diseases diagnosis and monitoring among children.

Optical Coherence Tomography Normative Peripapillary Retinal Nerve Fiber Layer and Macular Data in Children 0-5 Years of Age

PURPOSE

To determine reference values for the peripapillary retinal nerve fiber layer (pRNFL) and macula in children 0-5 years of age.

DESIGN

Prospective cross-sectional study.

METHODS

This study was set in a single large academic pediatric ophthalmology practice. Healthy, full-term children 0 to <6 years of age presenting for surgery under general anesthesia were prospectively recruited for participation. Excluded were children with systemic neurologic disease, optic nerve or retinal disease (even if unilateral) or any bilateral ocular disease process, and eyes with amblyopia, ocular disease, or spherical equivalent refractive error outside of -3.00 to +8.00 diopters. Following general anesthesia, OCT scans of the optic nerve and retina were acquired using an HRA+OCT Spectralis with Flex module (Heidelberg Engineering). Automated segmentation of the pRNFL and retinal layers was followed by manual correction.

RESULTS

Data were obtained from normal eyes of 57 participants (mean age 2.28 ± 1.50 years). Mean global pRNFL thickness was 107.6 ± 10.3 μm. Mean global pRNFL thickness was not dependent on age but showed a negative relationship with axial length (P = .01). The mean total macular volume was 8.56 ± 0.259 mm³ (n = 38). No relationship was found between total macular volume and age. Ganglion cell layer, ganglion cell complex, and inner nuclear layer volumes showed an inverse relationship with age while the photoreceptor layers showed a logarithmic increase with age.

CONCLUSIONS

Global pRNFL thickness measurements remain stable over time. Macular volume and thickness values of segmented retinal layers reflect the development of the macula with age.

The Optimal Diameter for Circumpapillary Retinal Nerve Fiber Layer Thickness Measurement by SD-OCT in Glaucoma

PURPOSE

To evaluate the diagnostic power for glaucoma detection using circumpapillary retinal nerve fiber layer (cRNFL) thickness in 3 diameter sizes from the center of the optic nerve head (ONH) by spectral domain optical coherence tomography.

PATIENTS AND METHODS

In this cross-sectional study, case-control, 437 eyes diagnosed with glaucoma and 183 eyes of healthy controls underwent spectral domain optical coherence tomography of the ONH, visual field testing, and a clinical examination. cRNFL was measured by circular scans in 3.5 (C1), 4.1 (C2), and 4.7 mm (C3) distance from the center of the ONH. Receiver-operator characteristic analysis was used to assess diagnostic power to detect glaucoma; furthermore, patient-specific maximum localized damage was analyzed.

RESULTS

In C1, mean global cRNFL was 70.03±18.2 μm in glaucomatous eyes and 93.46±9.9 μm in controls. Respectively, cRNFL in C2 was 61.39±14.9 and 80.43±8.4 μm as well as 55.25±12.8 and 70.70±6.7 μm in C3. Using receiver-operator characteristic analysis, the area under the curve (AUC) for cRNFL was 0.855 in C1, 0.850 in C2, and 0.843 in C3. Mean AUCs in ONH sectors ranged from 0.699 to 0.846 and did not exceed AUC of the best scoring global parameter.

CONCLUSIONS

Comparing 3.5, 4.1, and 4.7 mm diameters for cRNFL measurement, the inner circle at 3.5 mm distance showed the highest AUC to differentiate glaucoma from healthy controls. However, levels of diagnostic power from wider circular scans were not significantly different and were comparable. Moreover, sectorial cRNFL measurements were nonsuperior. The use of the ONH sector with the highest localized damage seems not to increase diagnostic power.

The correlation between the thickness of the inner macular layers and the mean deviation of the visual field in children with primary congenital glaucoma

PURPOSE

To analyse the association between the thickness of the circumpapillary retinal nerve fibre layer (cpRNFL) and the thickness of the inner macular layers with the mean deviation of the visual field (MD) in children with primary congenital glaucoma (PCG).

MATERIAL AND METHODS

A total of 41 children with PGC were included in the study. They all had a complete ophthalmological examination, including visual acuity, intraocular pressure, funduscopy, Octopus™ visual field, as well as circumpapillar and macular spectral domain optical coherence tomography (SD-OCT). SD-OCT with automated segmentation was used to measure the thicknesses and volumes of the macular retinal nerve fibre layer (mRNFL), ganglion cell layer (GCL), and inner plexiform layer.

RESULTS

The mean age was 11.2±3.86 years, and the mean MD was 8.85±6.76dB. The visual field was classified as normal in 46% of the patients, and 20% of the patients had a concentrical restriction of the visual field. A positive correlation was found between between the cup-to-disc ratio and the MD, r=0.51 (P=.004). The correlation between the MD and the cpRNFL was r=-0.63 (P<.001), and r=-0.69 (P<.001) with the GCL.

CONCLUSIONS

Inner macular layers thickness and cpRNFL thickness show a good correlation with the mean deviation of the visual field in children with primary congenital 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.