Estimating Lead Time Gained by Optical Coherence Tomography in Detecting Glaucoma before Development of Visual Field Defects

Association Analysis between Cognitive Function Score and Inner Macular Thickness/Visual Field Sensitivity in Glaucoma Patients

(1) Background: Previous research has investigated the relationship between cognitive impairment, optical coherence tomography (OCT), visual fields (VF), and VF reliability in smaller patient samples using various cognitive assessment tools. This study analyzed the relationship between cognitive function scores using the Mini-Cog test and inner macular thickness (IMT) and VF sensitivity in glaucoma patients. (2) Methods: A retrospective analysis was conducted on 984 patients with 1897 eyes. Assessments included age, sex, intraocular pressure (IOP), and Mini-Cog test scores. Abnormal Mini-Cog scores were observed in 89 patients (9%). Using a mixed-effects model adjusted for background factors, the association between Mini-Cog scores and IMT, parafoveal (PF)-IMT, mean deviation (MD), pattern standard deviation, fixation losses (FL), false negatives (FN), and false positives (FP) was analyzed. (3) Results: Abnormal Mini-Cog scores (≤2) were associated with thinning of the IMT and PF-IMT, worse MDs, and higher FN and FP rates but not with PSD or FL. (4) Conclusions: Glaucoma patients with low cognitive function scores exhibited more advanced glaucoma-related changes in VF testing and morphological tests. Further longitudinal studies are needed to explore the relationship between glaucoma and cognitive impairment.

Time to Glaucoma Progression Detection by Optical Coherence Tomography and Visual Field in Glaucoma Individuals of African Descent

PURPOSE

To examine the time to glaucoma progression detection by retinal nerve fiber layer thickness (RNFLT) and visual field (VF) among individuals of African descent (AD).

DESIGN

Retrospective cohort study.

METHODS

This multicenter study included eyes with glaucoma from individuals of AD from the Diagnostic Innovations in Glaucoma Study and the African Descent and Glaucoma Evaluation Study with ≥2 years/5 visits of optic nerve head RNFLT and 24-2 VF examinations.

INTERVENTION OR OBSERVATION PROCEDURE

Rates of VF mean deviation (MD) and RNFLT worsening were analyzed using linear mixed-effects models, and longitudinal data were simulated using the variability estimates.

MAIN OUTCOME MEASURE

The simulated time to detect trend-based glaucoma progression was assessed with assumed rates of VF MD and RNFLT change derived from the cohort (25th, 50th, and 75th percentile [as p25, median, and p75] slopes and mean slopes). Severity-stratified analyses were also performed.

RESULTS

We included 184 eyes from 128 subjects of AD (mean baseline age 63.4 years; VF MD -4.2 dB; RNFLT 80.2 µm). The p25, median, mean, and p75 rates of change were -0.43, -1.01, -1.15, and -1.64 µm per year for RNFLT, and 0.00, -0.21, -0.30, and -0.51 dB per year for VF MD, respectively. Compared with VF MD, RNFLT showed an overall shorter mean time to progression detection (time difference 0.4-1.7 years), with the mean rates showing the largest difference (RNFLT 5.2 years vs VF MD 6.9 years). Similarly, we found an overall shorter time to detect RNFLT progression, compared with that of VF MD progression, in eyes with mild glaucoma (≥1 year earlier) and in eyes with moderate to advanced glaucoma (∼0.5 year earlier).

CONCLUSIONS

Computer simulation showed a potentially shorter time to detect RNFLT progression than VF MD progression in eyes from individuals of AD. Our findings support the importance of using RNFLT to detect progressive glaucoma in individuals of AD.

Unveiling Novel Structural Biomarkers for the Diagnosis of Glaucoma

Glaucoma, a leading cause of irreversible blindness, poses a significant global health burden. Early detection is crucial for effective management and prevention of vision loss. This study presents a collection of novel structural biomarkers in glaucoma diagnosis. By employing advanced imaging techniques and data analysis algorithms, we now can recognize indicators of glaucomatous progression. Many research studies have revealed a correlation between the structural changes in the eye or brain, particularly in the optic nerve head and retinal nerve fiber layer, and the progression of glaucoma. These biomarkers demonstrate value in distinguishing glaucomatous eyes from healthy ones, even in the early stages of the disease. By facilitating timely detection and monitoring, they hold the potential to mitigate vision impairment and improve patient outcomes. This study marks an advancement in the field of glaucoma, offering a promising avenue for enhancing the diagnosis and possible management.

Classifying glaucoma exclusively with OCT: comparison of three clustering algorithms derived from machine learning

BACKGROUND/AIMS

To objectively classify eyes as either healthy or glaucoma based exclusively on data provided by peripapillary retinal nerve fiber layer (pRNFL) and ganglion cell-inner plexiform (GCIPL) measurements derived from spectral-domain optical coherence tomography (SD-OCT) using machine learning algorithms.

METHODS

Three clustering methods (k-means, hierarchical cluster analysis -HCA- and model-based clustering-MBC-) were used separately to classify a training sample of 109 eyes as either healthy or glaucomatous using solely 13 SD-OCT parameters: pRNFL average and sector thicknesses and GCIPL average and minimum values together with the six macular wedge-shaped regions. Then, the best-performing algorithm was applied to an independent test sample of 102 eyes to derive close estimates of its actual performance (external validation).

RESULTS

In the training sample, accuracy was 91.7% for MBC, 81.7% for k-means and 78.9% for HCA (p value = 0.02). The best MBC model was that in which subgroups were allowed to have variable volume and shape and equal orientation. The MBC algorithm in the independent test sample correctly classified 98 out of 102 cases for an overall accuracy of 96.1% (95% CI, 92.3-99.8%), with a sensitivity of 94.3 and 100% specificity. The accuracy for pRNFL was 92.2% (95% CI, 86.9-97.4%) and for GCIPL 98.0% (95% CI, 95.3-100%).

CONCLUSIONS

Clustering algorithms in general (and MBC in particular) seem promising methods to help discriminate between healthy and glaucomatous eyes using exclusively SD-OCT-derived parameters. Understanding the relative merits of one method over others may also provide insights into the nature of the disease.

Detection and agreement of event-based OCT and OCTA analysis for glaucoma progression

OBJECTIVE

To examine event-based glaucoma progression using optical coherence tomography (OCT) and OCT angiography (OCTA).

METHODS

In this retrospective study, glaucoma eyes with ≥2-year and 4-visits of OCT/OCTA imaging were included. Peripapillary capillary density (CD) and retinal nerve fibre layer thickness (RNFL) were obtained from 4.5 mm × 4.5 mm optic nerve head (ONH) scans. Event-based OCT/OCTA progression was defined as decreases in ONH measurements exceeding test-retest variability on ≥2 consecutive visits. Visual field (VF) progression was defined as significant VF mean deviation worsening rates on ≥2 consecutive visits. Inter-instrument agreement on progression detection was compared using kappa(κ) statistics.

RESULTS

Among 147 eyes (89 participants), OCTA and OCT identified 33(22%) and 25(17%) progressors, respectively. They showed slight agreement (κ = 0.06), with 7(5%) eyes categorized as progressors by both. When incorporating both instruments, the rate of progressors identified increased to 34%. Similar agreement was observed in diagnosis- and severity-stratified analyses (κ < 0.10). Compared to progressors identified only by OCT, progressors identified only by OCTA tended to have thinner baseline RNFL and worse baseline VF. VF progression was identified in 11(7%) eyes. OCT and VF showed fair agreement (κ = 0.26), with 6(4%) eyes categorized as progressors by both. OCTA and VF showed slight agreement (κ = 0.08), with 4(3%) eyes categorized as progressors by both.

CONCLUSIONS

OCT and OCTA showed limited agreement on event-based progression detection, with OCT showing better agreement with VF. Both OCT and OCTA detected more progressors than VF. OCT and OCTA may provide valuable, yet different and complementary, information about glaucoma progression.

Current Status and Future Perspectives of Optic Nerve Imaging in Glaucoma

Being the primary site of degeneration, the optic nerve has always been the focus of structural glaucoma assessment. The technical advancements, mainly of optical coherence tomography (OCT), now allow for a very precise quantification of the optic nerve head and peripapillary retina morphology. By far the most commonly used structural optic nerve parameter is the thickness of the parapapillary retinal nerve fiber, which has great clinical utility but also suffers from significant limitations, mainly in advanced glaucoma. Emerging novel imaging technologies, such as OCT angiography, polarization-sensitive or visible-light OCT and adaptive optics, offer new biomarkers that have the potential to significantly improve structural glaucoma diagnostics. Another great potential lies in the processing of the data already available. Artificial intelligence does not only help increase the reliability of current biomarkers but can also integrate data from various imaging modalities and other clinical measures to increase diagnostic accuracy. And it can, in a more efficient way, draw information from available datasets, such as an OCT scan, compared to the current concept of biomarkers, which only use a fraction of the whole dataset.

Aging-associated changes of optical coherence tomography-measured ganglion cell-related retinal layer thickness and visual sensitivity in normal Japanese

PURPOSE

To report aging-associated change rates in circumpapillary retinal nerve fiber layer thickness (cpRNFLT) and macular ganglion cell-inner plexiform layer and complex thickness (MGCIPLT, MGCCT) in normal Japanese eyes and to compare the data in linear scaled visual field (VF) sensitivity of central 4 points of Humphrey Field Analyzer (HFA) 24-2 test (VF4TestPoints) to that in MGCIPLT in four 0.6-mm-diameter circles corresponding to the four central points of HFA 24-2 adjusted for retinal ganglion cell displacement (GCIPLT4TestPoints).

STUDY DESIGN

Prospective observational study METHODS: HFA 24-2 tests and spectral-domain optical coherence tomography (SD-OCT) measurements of cpRNFLT, MGCIPLT, MGCCT and GCIPLT4TestPoints were performed every 3 months for 3 years in 73 eyes of 37 healthy Japanese with mean age of 50.4 years. The time changes of SD-OCT-measured parameters and VF4TestPoints were analyzed using a linear mixed model.

RESULTS

The aging-associated change rates were -0.064 μm/year for MGCIPLT and and -0.095 for MGCCT (P=0.020 and 0.017), but could not be detected for cpRNFLT. They accelerated with aging at -0.009μm/year/year of age for MGCIPLT (P<0.001), at 0.011 for MGCCT (P<0.001) and at 0.013 for cpRNFLT(0.031). The aging-associated decline of -82.1 [1/Lambert]/year of VF4TestPoints corresponded to -0.095 μm/year of GCIPLT4TestPoints.

CONCLUSION

We report that aging-associated change rates of cpRNFLT, MGCIPLT and MGCCT in normal Japanese eyes were found to be significantly accelerated along with aging. Relationship between VF sensitivity decline rates and SD-OCT measured GCIPLT decline rates during physiological aging in the corresponding parafoveal retinal areas are also documented.

Associations between Chronic Kidney Disease and Thinning of Neuroretinal Layers in Multiethnic Asian and White Populations

Purpose

To evaluate the relationships between chronic kidney disease (CKD) with retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) thickness profiles of eyes in Asian and White populations.

Design

Cross-sectional analysis.

Participants

A total of 5066 Asian participants (1367 Malays, 1772 Indians, and 1927 Chinese) from the Singapore Epidemiology of Eye Diseases Study (SEED) were included, consisting of 9594 eyes for peripapillary RNFL analysis and 8661 eyes for GCIPL analysis. Additionally, 45 064 White participants (87 649 eyes) from the United Kingdom Biobank (UKBB) were included for both macular RNFL analysis and GCIPL analysis.

Methods

Nonglaucoma participants aged ≥ 40 years with complete data for estimated glomerular filtration rate (eGFR) were included from both SEED and UKBB. In SEED, peripapillary RNFL and GCIPL thickness were measured by Cirrus HD-OCT 4000. In UKBB, macular RNFL and GCIPL were measured by Topcon 3D-OCT 1000 Mark II. Chronic kidney disease was defined as eGFR < 60 ml/min/1.73 m2 in both data sets. To evaluate the associations between kidney function status with RNFL and GCIPL thickness profiles, multivariable linear regression with generalized estimating equation models were performed in SEED and UKBB data sets separately.

Main Outcome Measures

Average peripapillary and macular RNFL thickness and macular GCIPL thickness.

Results

In SEED, after adjusting for age, gender, ethnicity, systolic blood pressure, antihypertensive medication, diabetes, hyperlipidemia, body mass index, smoking status, and intraocular pressure, presence of CKD (β = -1.31; 95% confidence interval [CI], -2.37 to -0.26; P = 0.015) and reduced eGFR (per 10 ml/min/1.73 m2; β = -0.32; 95% CI, -0.50 to -0.13; P = 0.001) were associated with thinner average peripapillary RNFL. Presence of CKD (β = -1.63; 95% CI, -2.42 to -0.84) and reduced eGFR (per 10 ml/min/1.73 m2; β = -0.30; 95% CI, -0.44 to -0.16) were consistently associated with thinner GCIPL in SEED (all P < 0.001). In UKBB, after adjusting for the above-mentioned covariates (except ethnicity), reduced eGFR (per 10 ml/min/1.73 m2; β = -0.06; 95% CI, -0.10 to -0.01; P = 0.008) was associated with thinner macular RNFL and CKD (β = -0.62; 95% CI, -1.16 to -0.08; P = 0.024) was associated with thinner average GCIPL.

Conclusion

We consistently observed associations between CKD and thinning of RNFL and GCIPL across Asian and White populations' eyes. These findings further suggest that compromised kidney function is associated with RNFL and GCIPL thinning.

Financial Disclosures

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Smoking and progressive retinal nerve fibre layer thinning in glaucoma

BACKGROUND/AIMS

To investigate the relationship between smoking and smoking intensity, and the rate of retinal nerve fibre layer (RNFL) thinning in patients with primary open angle glaucoma (POAG).

METHODS

In this longitudinal study, patients with POAG who had at least 3 years of follow-up with a minimum of 5 visits of optical coherence tomography (OCT) were enrolled. The smoking intensity was calculated as the pack-year at the baseline OCT. Univariable and multivariable linear mixed models were used to determine the effect of each parameter on the rates of RNFL thinning over time. Non-linear least-squares estimation with piecewise regression model was used to investigate the cut-off point for the relationship between circumpapillary RNFL thinning and smoking intensity.

RESULTS

A total of 466 eyes of 314 patients were included over the mean (95% CI) follow-up of 6.6 (6.4 to 6.7) years. Of the 314 patients, 121 (39%) had reported any history of smoking. Greater smoking intensity was associated with faster RNFL thinning (-0.06 (95% CI -0.11 to 0.00) µm/year per 10 pack-year higher; p=0.031) after adjusted for confounding factors. RNFL thinning became significantly faster when smoking intensity was >8 pack-year.

CONCLUSIONS

Smoking intensity is associated with faster rates of RNFL thinning. Evaluation of smoking intensity might add information to the assessment of risk of glaucoma progression. Future studies are required to explore if withdrawing smoking as a modifiable risk factor can decrease progression in patients with glaucoma.

Optical Coherence Tomography Angiography (OCTA) Differences in Vessel Perfusion Density and Flux Index of the Optic Nerve and Peri-Papillary Area in Healthy, Glaucoma Suspect and Glaucomatous Eyes

Purpose

To assess the ability of vascular perfusion parameters determined by optical coherence tomography angiography (OCTA) to detect and monitor glaucoma.

Methods

This prospective study included healthy, glaucoma suspect and glaucomatous eyes. All eyes underwent comprehensive glaucoma examination, including visual field tests and ocular imaging scans by OCTA. Parameters measured included retinal nerve fiber layer (RNFL) thickness, ganglion cell analysis (GCA), vascular perfusion density (VPD) and flux index (FI) of the optic nerve and peri-papillary area. Ocular parameters in healthy, glaucoma suspect, and glaucomatous eyes were compared by generalized estimating equations (GEE) with adjustments for age, with their relationships analyzed by Pearson's correlation coefficient. Rates of change per year were compared in glaucomatous eyes with and without glaucoma progression.

Results

This study enrolled 238 eyes, including 56 healthy, 79 glaucoma suspect, and 103 glaucomatous eyes. After adjustments for age, the average VPD (45.40 ± 0.19% vs 45.05 ± 0.22% vs 42.89 ± 0.32%, p < 0.001) and FI (0.4210 ± 0.0055 vs 0.4105 ± 0.0039 vs 0.3801 ± 0.0048, p < 0.001) in these three groups differed significantly. Average VPD in the glaucoma group was inversely associated with the severity of glaucoma, being 43.99 ± 0.32%, 42.63 ± 0.43% and 39.27 ± 0.48% in eyes with early, moderate and severe glaucoma, respectively (p < 0.001). Average VPD, as well as VPD in the superior and inferior quadrants correlated well with both OCT determined RNFL and visual field parameters. The decreases per year in both superior (-0.012 vs -0.001, p = 0.002) and inferior (-0.008 vs -0.003, p = 0.007) FI were significantly greater in glaucomatous eyes with than without glaucoma progression.

Conclusion

Both VPD and FI as measured by OCTA are promising ocular parameters that can distinguish between normal and glaucomatous eyes. VPD is sensitive in comparing eyes at different glaucoma stages, whereas FI can detect rates of glaucoma progression.

Trial Registration

Thai Clinical Trial Registry, TCTR20181031002.

Retinal Ganglion Cell Functional Recovery after Intraocular Pressure Lowering Treatment Using Prostaglandin Analogs in Glaucoma Suspects: A Prospective Pilot Study

Aim and background

To evaluate the ability of pattern electroretinogram (PERG) to detect improvement of retinal ganglion cell (RGC) function in glaucoma suspects (GS) after medically reducing intraocular pressure (IOP) using prostaglandin analog drops.

Materials and methods

Six subjects (eight eyes) received topical IOP lowering treatment based on their clinical examination and were observed at Manhattan Eye, Ear & Throat Hospital over an average of 3.1 ± 2.2 months. During this time, participants underwent a full ophthalmologic exam and were evaluated with a Humphrey visual field analyzer (HFA) 24-2 [24-2 mean deviation (MD), 24-2 pattern standard deviation (PSD), and 24-2 visual field indices (VFI)], Diopsys NOVA PERG optimized for glaucoma [magnitude (Mag), magnitudeD (MagD), and magnitudeD/magnitude ratio (MagD/Mag ratio)] and optical coherence tomography (OCT)-derived average retinal nerve fiber layer thickness (avRNFLT) and average ganglion cell layer + inner plexiform layer (avGCL + IPL) thicknesses at baseline visit (pretreatment) and 3 months later (posttreatment). Goldman applanation tonometry was used to measure IOP at each visit. Paired sample t-tests were conducted to determine the statistical significance of the change in IOP, HFA indices, PERG parameters, and OCT thickness measurements between the two visits.

Results

Lowering IOP by 22.29% resulted in a significant increase (32.98 and 15.49%) in MagD [t (7) = -3.174, 95% confidence interval (CI) = -0.53, -0.08, p = 0.016] and MagD/Mag ratio [t (7) = -3.233, 95% CI = -0.20, -0.03, p = 0.014], respectively. There was a positive percentage change for all variables of interest, however, 24-2 MD, Mag, avRNFLT, and GCL+ IPLT did not reach statistical significance.

Conclusion

After reducing IOP by 22.29% for a duration of 3.1 months, the PERG parameters, MagD and MagD/Mag ratio, significantly improved by 32.98 and 15.49%, respectively.

Clinical significance

Pattern electroretinogram (PERG) may be a crucial tool for clinicians to locate a window of opportunity in which degenerating yet viable RGCs could be rescued from irreversible damage. We suggest consideration of PERG as a tool in early retinal ganglion cell (RGC) dysfunction detection as well as for monitoring IOP lowering treatment.

How to cite this article

Tirsi A, Gliagias V, Sheha H, et al. Retinal Ganglion Cell Functional Recovery after Intraocular Pressure Lowering Treatment Using Prostaglandin Analogs in Glaucoma Suspects: A Prospective Pilot Study. J Curr Glaucoma Pract 2023;17(4):178-190.

Retinal OCT speckle as a biomarker for glaucoma diagnosis and staging

This paper presents a novel image analysis strategy that increases the potential of macular Optical Coherence Tomography (OCT) by using speckle features as biomarkers in different stages of glaucoma. A large pool of features (480) were computed for a subset of macular OCT volumes of the Leuven eye study cohort. The dataset contained 258 subjects that were divided into four groups based on their glaucoma severity: Healthy (56), Mild (94), Moderate (48), and Severe (60). The OCT speckle features were categorized as statistical properties, statistical distributions, contrast, spatial gray-level dependence matrices, and frequency domain features. The averaged thicknesses of ten retinal layers were also collected. Kruskal-Wallis H test and multivariable regression models were used to infer the most significant features related to glaucoma severity classification and to the correlation with visual field mean deviation. Four features were selected as being the most relevant: the ganglion cell layer (GCL) and the inner plexiform layer (IPL) thicknesses, and two OCT speckle features, the data skewness computed on the retinal nerve fiber layer (RNFL) and the scale parameter (a) of the generalized gamma distribution fitted to the GCL data. Based on a significance level of 0.05, the regression models revealed that RNFL skewness exhibited the highest significance among the features considered for glaucoma severity staging (p-values of 8.6×10-6 for the logistic model and 2.8×10-7 for the linear model). Furthermore, it demonstrated a strong negative correlation with the visual field mean deviation (ρ=-0.64). The post hoc analysis revealed that, when distinguishing healthy controls from glaucoma subjects, GCL thickness is the most relevant feature (p-value of 8.7×10-5). Conversely, when comparing the Mild versus Moderate stages of glaucoma, RNFL skewness emerged as the only feature exhibiting statistical significance (p-value = 0.001). This work shows that macular OCT speckle contains information that is currently not used in clinical practice, and not only complements structural measurements (thickness) but also has a potential for glaucoma staging.

Sector-Based Regression Strategies to Reduce Refractive Error-Associated Glaucoma Diagnostic Bias When Using OCT and OCT Angiography

Purpose

This cross-sectional study aimed to investigate the sectoral variance of optical coherence tomography (OCT) and OCT angiography (OCTA) glaucoma diagnostic parameters across eyes with varying degrees of refractive error.

Methods

Healthy participants, including individuals with axial ametropia, enrolled in the Hong Kong FAMILY cohort were imaged using the Avanti/AngioVue OCT/OCTA system. The OCT and OCTA parameters obtained include peripapillary nerve fiber layer thickness (NFLT), peripapillary nerve fiber layer plexus capillary density (NFLP-CD), and macular ganglion cell complex thickness (GCCT). Sectoral measurements of NFLT, NFLP-CD, and GCCT were based on sectors and hemispheres.

Results

A total of 1339 eyes from 791 participants were stratified based on spherical equivalent refraction: high myopia (<-6 D), low myopia (-6 D to -1 D), emmetropia (-1 D to 1 D), and hyperopia (>1 D). Multivariable broken stick regression models, accounting for age, sex, and signal strength, showed that all NFLT sectors except temporally, the inferior GCCT hemisphere, and half of the NFLP-CD sectors were more affected by ametropia-related covariates than the corresponding global parameters. As expected, the false-positive rates in those sectors were elevated. Finally, sector-specific axial length (AL) and spherical equivalent (SE) adjustments helped reduce the elevated false-positive rates.

Conclusions

The effect of optical magnification is even more prominent among sectors than the global parameters. AL- and SE-based adjustments should be individualized to each sector to mitigate this magnification bias effectively.

Translational Relevance

Identifying sectoral differences among diagnostic parameters and adopting these sector-based adjustments into commercial OCT systems will hopefully reduce false-positive rates related to refractive error.

Optical Coherence Tomography and Optical Coherence Tomography Angiography: Essential Tools for Detecting Glaucoma and Disease Progression

Early diagnosis and detection of disease progression are critical to successful therapeutic intervention in glaucoma, the leading cause of irreversible blindness worldwide. Optical coherence tomography (OCT) is a non-invasive imaging technique that allows objective quantification in vivo of key glaucomatous structural changes in the retina and the optic nerve head (ONH). Advances in OCT technology have increased the scan speed and enhanced image quality, contributing to early glaucoma diagnosis and monitoring, as well as the visualization of critically important structures deep within the ONH, such as the lamina cribrosa. OCT angiography (OCTA) is a dye-free technique for noninvasively assessing ocular microvasculature, including capillaries within each plexus serving the macula, peripapillary retina and ONH regions, as well as the deeper vessels of the choroid. This layer-specific assessment of the microvasculature has provided evidence that retinal and choroidal vascular impairments can occur during early stages of glaucoma, suggesting that OCTA-derived measurements could be used as biomarkers for enhancing detection of glaucoma and its progression, as well as to reveal novel insights about pathophysiology. Moreover, these innovations have demonstrated that damage to the macula, a critical region for the vision-related quality of life, can be observed in the early stages of glaucomatous eyes, leading to a paradigm shift in glaucoma monitoring. Other advances in software and hardware, such as artificial intelligence-based algorithms, adaptive optics, and visible-light OCT, may further benefit clinical management of glaucoma in the future. This article reviews the utility of OCT and OCTA for glaucoma diagnosis and disease progression detection, emphasizes the importance of detecting macula damage in glaucoma, and highlights the future perspective of OCT and OCTA. We conclude that the OCT and OCTA are essential glaucoma detection and monitoring tools, leading to clinical and economic benefits for patients and society.

Association of Rates of Ganglion Cell and Inner Plexiform Thinning With Development of Glaucoma in Eyes With Suspected Glaucoma

Importance

In eyes with suspected glaucoma, it is clinically relevant to find diagnostic tests for the risk of development of perimetric glaucoma.

Objective

To investigate the association between rates of ganglion cell/inner plexiform layer (GCIPL) and circumpapillary retinal nerve fiber layer (cpRNFL) thinning and the development of perimetric glaucoma in eyes with suspected glaucoma.

Design, Setting, and Participants

This observational cohort study used data collected in December 2021 from a tertiary center study and a multicenter study. Participants with suspected glaucoma were followed up for 3.1 years. The study was designed in December 2021 and finalized in August 2022.

Exposures

Development of perimetric glaucoma was defined as having 3 consecutive results showing abnormal visual fields. Using linear mixed-effect models, rates of GCIPL were compared between eyes with suspected glaucoma that did and did not develop perimetric glaucoma. A joint longitudinal multivariable survival model was used to investigate the performance of rates of GCIPL and cpRNFL thinning in predicting the risk of developing perimetric glaucoma.

Main Outcomes and Measures

Rates of GCIPL thinning and hazard ratio (HR) of developing perimetric glaucoma.

Results

Among a total of 462 participants, the mean (SD) age was 63.3 (11.1) years, and 275 patients (60%) were female. Of 658 eyes, 153 eyes (23%) developed perimetric glaucoma. The mean rates of GCIPL thinning were faster in eyes that developed perimetric glaucoma (-1.28 vs -0.66 μm/y for minimum GCIPL thinning; difference, -0.62; 95% CI, -1.07 to -0.16; P = .02). Based on the joint longitudinal survival model, every 1-μm/y faster rate of minimum GCIPL and rate of global cpRNFL thinning were associated with a 2.4 and 1.9 higher risk of developing perimetric glaucoma, respectively (HR, 2.4; 95% CI, 1.8 to 3.2, and HR, 1.99; 95% CI, 1.76 to 2.22, respectively; P < .001). Among the predictive factors, African American race (HR, 1.56; 95% CI, 1.05 to 2.34; P = .02), male sex (HR, 1.47; 95% CI, 1.02 to 2.15; P = .03), 1-dB higher baseline visual field pattern standard deviation (HR, 1.73; 95% CI, 1.56 to 1.91; P < .001), and 1-mm Hg higher mean intraocular pressure during follow-up (HR, 1.11; 95% CI, 1.05 to 1.17; P < .001) were associated with higher risk of developing perimetric glaucoma.

Conclusions and Relevance

This study found that faster rates of GCIPL and cpRNFL thinning were associated with higher risks of developing perimetric glaucoma. Rates of cpRNFL thinning and specifically GCIPL thinning may be useful measures for monitoring eyes with suspected glaucoma.

Agreement of Diagnostic Classification Between Structural Parameters in Pre-Perimetric and Early Perimetric Glaucoma

PRCIS

In both pre-perimetric and early perimetric glaucoma, the diagnostic agreements between optic disk, retinal nerve fiber layer, and ganglion cell-inner plexiform layer parameters based on Cirrus HD-OCT normative database classification were mostly fair, suggesting that abnormal classification in 1 anatomic area may suffice for the diagnosis of glaucoma in early stages.

PURPOSE

To evaluate the agreement of normative database diagnostic classification between optic disk, retinal nerve fiber layer (RNFL), and ganglion cell-inner plexiform layer (GCIPL) in patients with early glaucoma.

METHODS

Retrospective cross-sectional study involving 66 eyes (66 patients) with pre-perimetric and 97 eyes (97 patients) with early perimetric glaucoma. Normative database diagnostic classifications were retrieved from Cirrus HD-OCT scans of 1 eye per participant. An eye was considered abnormal if any of the optic disk, RNFL, or GCIPL was abnormal (yellow or red color-coded classification). For combined parameters, the eye had to be flagged as abnormal by both classifications, regardless of the parameters that were abnormal (global or sectorial). The agreement was assessed with Cohen's Kappa statistics.

RESULTS

The agreement between RNFL and GCIPL was fair in both pre-perimetric (κ=0.25) and perimetric glaucoma (κ=0.21). Agreements between RNFL or GCIPL and optic nerve head parameters (rim area and vertical cup-to-disk ratio; VCDR) were inconclusive due to insufficient data ( P >0.05). Combining GCIPL and rim area agreed fairly with RNFL both in pre-perimetric (κ=0.21) and perimetric glaucoma (κ=0.33). The best classification agreement (moderate) was achieved with the comparison of RNFL-rim area versus VCDR (κ=0.48 in pre-perimetric, 0.45 in perimetric glaucoma). There were no significant differences between pre-perimetric and perimetric glaucoma coefficients of classification agreement.

CONCLUSIONS

The normative database diagnostic agreements between optic disk, RNFL, and GCIPL were mostly fair in both pre-perimetric and early perimetric glaucoma. Clinicians should not wait for multiple structures to show abnormality on OCT to diagnose early glaucoma.

Rates of Choroidal and Neurodegenerative Changes Over Time in Diabetic Patients Without Retinopathy: A 3-Year Prospective Study

PURPOSE

To evaluate the longitudinal changes of retinal neurodegeneration and choroidal thickness in diabetic patients with and without diabetic retinopathy (DR).

DESIGN

Prospective observational cohort study.

METHODS

This prospective observational cohort study recruited type 2 diabetic patients from a community registry in Guangzhou. All participants underwent annual ocular examinations via swept-source optical coherence tomography that obtained choroid thickness (CT), retinal thickness (RT), and ganglion cell-inner plexiform layer (GC-IPL) thickness. The changes in GC-IPL, CT, and RT between patients who developed incident DR (IDR) or remained non-DR (NDR) were compared during a 3-year follow-up.

RESULTS

Among 924 patients, 159 (17.2%) patients developed IDR within the 3-year follow-up. A reduction in GC-IPL, RT, and CT was observed in NDR and IDR; however, CT thinning in patients with IDR was significantly accelerated, with an average CT reduction of -6.98 (95% CI: -8.26, -5.71) μm/y in patients with IDR and -3.98 (95% CI: -4.60, -3.36) μm/y in NDR patients (P < .001). Reductions in average GC-IPL thickness over 3 years were -0.97 (95% CI: -1.24, -0.70) μm/y in patients with IDR and -0.76 (95% CI: -0.82, -0.70) μm/y in NDR patients (P = .025). After adjusting for confounding factors, the average CT and GC-IPL thinning were significantly faster in patients with IDR compared with those who remained NDR by 2.09 μm/y (95% CI: 1.01, 3.16; P = .004) and -0.29 μm/y (95% CI: -0.49, -0.09; P = .004), respectively. The RT in the IDR group increased, whereas the RT in the NDR group decreased over time, with the adjusted difference of 2.09 μm/y (95% CI: 1.01, 3.16; P < .001) for central field RT.

CONCLUSIONS

The rate of retinal neurodegeneration and CT thinning were significantly different between the eyes that developed IDR and remained NDR during the 3-year follow-up, but both groups observed thickness reduction. This indicates that GC-IPL and CTs may decrease before the clinical manifestations of DR.

Structural and vascular changes in glaucoma with single-hemifield defect: predictors of opposite hemifield visual field progression

PURPOSE

To investigate longitudinal changes in optic nerve head (ONH) superficial vessel density (VD), macular VD, circumpapillary retinal nerve fiber layer (RNFL) thickness, and macular ganglion cell-inner plexiform layer (GCIPL) thickness, and their associations with future VF defects in unaffected hemifields of primary open angle glaucoma (POAG) eyes with baseline VF defect confined to a single hemifield.

METHODS

This retrospective observational study included 61 POAG eyes with VF defect confined to a single hemifield monitored over a mean follow-up time of 2.7 years. Development of VF defect in opposite hemifield was defined based the Early Manifest Glaucoma Trail criteria. Each eye was classified into either "conversion" or "no conversion" groups according to development of VF defect in the unaffected hemifield. The rates of longitudinal changes in VD and structure parameters in each hemiretina were compared between the two groups. A Cox proportional hazard model was used to identify potential risk factors for VF conversion in the unaffected hemifield.

RESULTS

Among 61 eyes, 17 eyes (27.9%) were classified as "conversion" and 44 eyes (72.1%) were classified as "non-conversion" groups. The conversion group exhibited significantly greater rates of both VD and structural changes in both hemiretinas. In Cox proportional hazard model, greater rate of change in GCIPL thickness, ONH superficial VD, and macular VD of both hemiretinas and greater rate of change in RNFL thickness of the unaffected hemiretina were identified as risk factors for VF conversion in the unaffected hemifield.

CONCLUSIONS

Monitoring progressive changes in VD and structural parameters effectively predict future VF defect in the opposite hemifields of POAG eyes with single-hemifield defects.

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.

Glaucoma Detection in Myopic Eyes: Structural and Vascular Assessment by Optic Coherence Tomography Methods

PRCIS

Retinal nerve fiber layer (RNFL) thickness is helpful in the diagnosis of glaucoma in myopic eyes but neuroretinal rim (NRR) thickness is the most valuable measure. However, changes in optical coherence tomography angiography (OCT-A) parameters are insufficient for the diagnosis of mild to moderate glaucoma in myopia.

PURPOSE

To detect how a multimodal evaluation, which includes RNFL, NRR thickness, and optic nerve head (ONH) OCT-A, affects glaucoma diagnosis in myopic patients.

MATERIALS AND METHODS

Parameters of healthy myopic and myopic glaucoma eyes with an axial length of ≥24 mm were compared. The ONH structural features and peripapillary RNFL thickness were determined with Cirrus 5000 HD-OCT (Cirrus HD-OCT; Carl Zeiss Meditec, Dublin, CA). The Cirrus 5000 HD-OCT with AngioPlex was utilized to perform OCT-A imaging. The sensitivity and specificity levels were calculated by the best cut-off values with area under curve (AUC).

RESULTS

One hundred healthy myopic and 54 myopic glaucoma eyes were evaluated. In all areas, myopic glaucoma patients exhibited lower RNFL and NRR thickness than healthy myopic individuals ( P <0.05), with the exception of nasal quadrant RNFL thickness ( P =0.152). The mean entire and 4 quadrants of global radial peripapillary capillary (RPC)-perfusion and global RPC flux index (FI) were significantly lower in the group of myopic glaucoma patients except for the nasal quadrant mean RPC perfusion ( P =0.224). The average RNFL and NRR thickness had a significant difference in AUC for the diagnosis of glaucoma in myopic individuals ( P =0.001, for each). The average NRR showed excellent diagnostic performance, whereas the average RNFL showed good diagnostic performance. Average RPC perfusion and average RPC FI showed poor diagnostic ability. The average NRR AUC was more significant than average RPC perfusion and average RPC FI AUC ( P <0.001).

CONCLUSIONS

Although RNFL thickness was helpful to diagnose glaucoma in patients with myopia, the diagnostic power of NRR thickness performed best. OCT-A parameters showed poor diagnostic accuracy for glaucoma and the observed perfusion decrease in myopic glaucoma eyes was not sufficiently discriminative compared with NRR and RNFL thickness measurements.

Deep learning and optical coherence tomography in glaucoma: Bridging the diagnostic gap on structural imaging

Glaucoma is a leading cause of progressive blindness and visual impairment worldwide. Microstructural evidence of glaucomatous damage to the optic nerve head and associated tissues can be visualized using optical coherence tomography (OCT). In recent years, development of novel deep learning (DL) algorithms has led to innovative advances and improvements in automated detection of glaucomatous damage and progression on OCT imaging. DL algorithms have also been trained utilizing OCT data to improve detection of glaucomatous damage on fundus photography, thus improving the potential utility of color photos which can be more easily collected in a wider range of clinical and screening settings. This review highlights ten years of contributions to glaucoma detection through advances in deep learning models trained utilizing OCT structural data and posits future directions for translation of these discoveries into the field of aging and the basic sciences.

Corneal Hysteresis and Rates of Neuroretinal Rim Change in Glaucoma

PURPOSE

To evaluate the impact of corneal hysteresis (CH) as a risk factor for progressive neuroretinal rim loss in glaucoma, as measured by spectral-domain OCT of the Bruch's membrane opening minimum rim width (MRW).

DESIGN

Prospective, observational cohort study.

PARTICIPANTS

The study group included 118 eyes of 70 subjects with glaucoma. The average follow-up time for the cohort was 3.9 ± 1.3 years, with an average of 6.4 ± 2.0 spectral-domain OCT tests, ranging from 4 to 12.

METHODS

Corneal hysteresis measurements were acquired at baseline using the Ocular Response Analyzer (Reichert Instruments). Linear mixed models were used to investigate the relationship between the rates of MRW loss and baseline CH. Multivariable analyses adjusted for other putative predictive factors for progression, including mean intraocular pressure (IOP), central corneal thickness (CCT), age, race, and baseline disease severity.

MAIN OUTCOME MEASURES

Effects of CH on the rate of MRW change over time.

RESULTS

Corneal hysteresis had a significant effect on rates of MRW progression over time. Each 1-mmHg lower CH was associated with -0.38 μm/year faster MRW loss (95% confidence interval [CI], -0.70 to -0.06; P = 0.019), after adjustment for other predictive factors. The mean IOP was also significantly associated with progression, with -0.35 μm/year (95% CI, -0.47 to -0.23 μm/year) faster MRW change for each 1-mmHg higher pressure (P < 0.001). In the analysis of predictive strength, the mean IOP was the strongest predictive factor (R2 = 23%), followed by CH (R2 = 14%) and baseline disease severity (R2 = 6%). Central corneal thickness explained only 3% of the variability in slopes of change in global MRW.

CONCLUSIONS

Lower CH measurements were associated with faster loss of the neuroretinal rim in glaucoma, as measured by MRW. The predictive ability of CH was superior to that of CCT. These findings suggest that CH is an important parameter to be considered in assessing the risk of glaucoma progression.

Cognitive Performance on the Montreal Cognitive Assessment Test and Retinal Structural and Functional Measures in Glaucoma

Background: Glaucoma, the leading cause of irreversible blindness, is classified as a neurodegenerative disease, and its incidence increases with age. Pathophysiological changes, such as the deposition of amyloid-beta plaques in the retinal ganglion cell layer, as well as neuropsychological changes, including cognitive decline, have been reported in glaucoma. However, the association between cognitive ability and retinal functional and structural measures in glaucoma, particularly glaucoma subtypes, has not been studied. We studied the association between cognitive ability and the visual field reliability indices as well as the retinal ganglion cell (RGC) count estimates in a cohort of glaucoma patients. Methods: A total of 95 eyes from 61 glaucoma patients were included. From these, 20 were normal-tension glaucoma (NTG), 25 were primary open-angle glaucoma (POAG), and 16 were glaucoma suspects. All the participants had a computerised Humphrey visual field (HVF) assessment and optical coherence tomography (OCT) scan and were administered the written Montreal Cognitive Assessment (MoCA) test. RGC count estimates were derived based on established formulas using the HVF and OCT results. A MoCA cut-off score of 25 and less was designated as cognitive impairment. Student’s t-test was used to assess differences between the groups. The Pearson correlation coefficient was used to assess the association between MoCA scores and retinal structural and functional measures. Results: Significant associations were found between MoCA scores and the false-negative and pattern standard deviation indices recorded on the HVF (r = −0.19, r = −0.22, p < 0.05). The mean IOP was significantly lower in the cognitively impaired group (i.e., MOCA ≤ 25) (13.7 ± 3.6 vs. 15.7 ± 4.5, p < 0.05). No significant association was found between RGC count estimates and MoCA scores. Analysis of these parameters in individual glaucoma subtypes did not reveal any group-specific significant associations either.

Impact of Glaucoma Severity on Rates of Neuroretinal Rim, Retinal Nerve Fiber Layer, and Macular Ganglion Cell Layer Thickness Change

PURPOSE

To determine the impact of glaucoma severity on rates of change of minimum rim width (MRW), peripapillary retinal nerve fiber layer (RNFL), and macular ganglion cell layer (GCL) thickness.

DESIGN

Prospective, cohort study.

METHODS

Glaucoma patients and healthy subjects had optical coherence tomography scans at 6-month intervals. Individual rates of change for MRW, RNFL, and GCL thickness were estimated with ordinary least-squares regression. Linear mixed-effect models were used to estimate the rate of change of each parameter and evaluate the impact of glaucoma severity (expressed by visual field mean deviation, MD) and age on these rates.

RESULTS

A total of 132 glaucoma patients and 57 healthy subjects were followed for a median of 4.3 years and 3.7 years, respectively. Healthy subjects had a statistically significant deterioration in MRW (-1.66 µm/year), RNFL (-0.46 µm/year), and GCL thickness (-0.22 µm/year). While glaucoma patients had a faster rate of change in each parameter compared with healthy subjects, only GCL thickness showed a statistically significant group difference (mean difference: -0.17 µm/year; P = .03). Older baseline age was associated with faster GCL thickness change (-0.07 µm/year; P = .03), but not other parameters. Baseline MD had no impact on the subsequent rates of change in any of the parameters.

CONCLUSIONS

The rates of MRW, RNFL, and GCL thickness change were not significantly influenced by glaucoma severity at baseline; however, GCL thickness was able to statistically contrast the rate of change between healthy subjects and glaucoma patients throughout the disease spectrum.

Intraocular Pressure Control Predicts Retinal Nerve Fiber Layer Thinning in Primary Angle Closure Disease: The CUPAL Study

PURPOSE

To determine the relationship of intraocular pressure (IOP) control with subsequent retinal nerve fiber layer (RNFL) thinning in patients with primary angle closure disease (PACD).

DESIGN

Prospective cohort study.

METHODS

The study monitored 517 treated PACD eyes from 280 Chinese patients at least 24 months. IOP was measured every 3 months using Goldmann applanation tonometry, and RNFLs were measured by spectral-domain optical coherence tomography (Spectralis, Heidelberg Engineering) every 6 months. IOP mean and fluctuation were calculated as the average and the coefficient of variation of IOP measurements during the first 18 months of the study period. The relationship between IOP and subsequent RNFL changes over time were examined using multivariable linear mixed models. Intraclass correlations at the patient and eye levels were also controlled using nested random intercepts in the models.

RESULTS

IOP mean (β = -1.20 µm/y per 1 mm Hg, P < .001) and IOP fluctuation (β = -3.10 µm/y per 10% unit change in the coefficient of variation, P < .001) were independently negatively associated with subsequent progressive global RNFL changes, after adjustment for age, sex, and baseline RNFL thickness. In the sectoral analysis, both higher mean IOP and IOP fluctuation predicted progressive RNFL thinning in the inferotemporal, superotemporal, superonasal, and temporal sectors in the order of strength of association. In the subgroup analysis by disease category, IOP fluctuation showed greater association with global RNFL thinning in eyes with primary angle closure glaucoma (P = .010) than in eyes without glaucomatous changes (P = .07).

CONCLUSIONS

In treated PACD eyes, large IOP fluctuation is an independent predictor for subsequent progressive RNFL thinning in addition to high mean IOP during follow-up.

Pattern Electroretinogram Parameters Are Associated with Optic Nerve Morphology in Preperimetric Glaucoma after Adjusting for Disc Area

Purpose

We examined the relationships between pattern electroretinogram and optical coherence tomography derived optic nerve head measurements, after controlling for disc area.

Methods

Thirty-two eyes from 20 subjects with preperimetric glaucoma underwent pattern electroretinogram and optical coherence tomography. Pattern electroretinogram parameters (Magnitude, MagnitudeD, and MagnitudeD/Magnitude ratio) and optic nerve head measurements (rim area, average cup to disc ratio, vertical cup to disc ratio, cup volume, retinal nerve fiber layer thickness sectors, and Bruch's membrane opening-minimum rim width thickness sectors) were analyzed after controlling for disc area.

Results

Magnitude and MagnitudeD were significantly associated with rim area (r ≥ 0.503, p ≤ 0.004). All pattern electroretinogram parameters significantly correlated with Bruch's membrane opening-minimum rim width sectors—temporal superior and nasal inferior (r = 0.400, p=0.039)—and retinal nerve fiber layer sectors—superior, nasal superior, and inferior (r ≥ 0.428, p ≤ 0.026). Magnitude and MagnitudeD explained an additional 26.8% and 25.2% of variance in rim area (B = 0.174 (95% CI: 0.065, 0.283), p=0.003, and B = 0.160 (95% CI: 0.056, 0.265), p=0.004), respectively. MagnitudeD and MagnitudeD/Magnitude ratio explained an additional 13.4% and 12.8% of the variance in Bruch's membrane opening-minimum rim width global (B = 38.921 [95% CI: 3.872, 73.970], p=0.031, and B = 129.024 (95% CI: 9.589, 248.460), p=0.035), respectively. All Bruch's membrane opening-minimum rim width sectors and retinal nerve fiber layer sectors (nasal superior, nasal inferior, and inferior) were significantly correlated with rim area (r ≥ 0.389, p ≤ 0.045).

Conclusion

PERG abnormalities can predict rim area loss in preperimetric glaucoma after controlling for disc area. We recommend controlling for disc area to increase diagnostic accuracy in early glaucoma.

Retinal Nerve Fiber Layer Thickness and Rim Area Profiles in Asians: Pooled Analysis from the Asian Eye Epidemiology Consortium

PURPOSE

To evaluate ethnic variations, ocular and systemic determinants of retinal nerve fibre layer (RNFL) thickness and neuroretinal rim area among Asians, using a large consortium of population-based eye studies.

DESIGN

Cross-sectional pooled-analysis.

PARTICIPANTS

22436 participants (22436 eyes) from 10 population-based studies (China, Hong Kong, India, Japan, Russia and Singapore) of the Asian Eye Epidemiology Consortium.

METHODS

Participants aged ≥40 years without glaucoma were included. All participants underwent spectral domain optical coherence tomography (OCT) imaging, systemic and ocular examinations. Data were pooled from each study. Multivariable regression analysis was performed to evaluate inter-ethnic, inter-machine variations, ocular and systemic factors associated with RNFL thickness and rim area, adjusting for age, gender, diabetes, intraocular pressure (IOP), spherical equivalent (SE), ethnicity, OCT model, and study group. When evaluating body mass index, smoking, and hypertension as exposures, these factors were additionally adjusted in the model.

MAIN OUTCOME MEASURE

Average RNFL thickness (μm) and rim area (mm²) RESULTS: Indian and Japanese eyes showed thinner RNFL, compared to other Asian ethnicities (β values ranging 7.31-12.76μm, P<0.001 for all pair-wise comparisons). Compared to measurements by Cirrus HD-OCT, RNFL was on average 7.29μm thicker when measured by Spectralis, 12.85μm thicker by Nidek, and 17.48μm thicker by Optovue (all P<0.001). Additionally, older age (per decade, β=-2.70; 95% confidence interval [CI], -2.85 to -2.55), diabetes (β=-0.72; 95%CI, -1.20 to -0.24), ), higher IOP (per mmHg, β=-0.07; 95% CI, -0.10 to -0.04), more myopic SE (per dioptre, β=-1.13; 95% CI, -1.19 to -1.07), cardiovascular disease (CVD, β=-0.94; 95% CI, -1.49 to -0.40), and hypertension (β=-0.68; 95% CI, -1.04 to -0.32), were associated with thinner RNFL (all P≤0.003). Similarly, older age (β=-0.019; 95% CI, -0.028 to -0.009), higher IOP (β=-0.010; 95% CI, -0.013 to -0.008) and more myopic SE (β=-0.025; 95% CI, -0.029 to -0.021) were associated with smaller rim area (all P<0.001).

CONCLUSIONS

In this large pooled-analysis of multiple Asian population studies, Indian and Japanese eyes were observed to have thinner RNFL profiles. In addition to previously known determinants, hypertension and CVD were associated with thinner RNFL. These findings further suggest the need of ethnic-specific normative database to improve glaucoma detection.

Microvascular and Structural Alterations of the Macula in Early to Moderate Glaucoma: An Optical Coherence Tomography-Angiography Study

In glaucoma, macular optical coherence tomography (OCT) typically shows a thinning of the three inner segments and OCT-angiography (OCTA) a reduction of the vascular density (VD). It is still unclear if glaucoma directly affects macular VD. This retrospective study included 31 glaucoma patients of early and moderate stage (GS1, GS2, Mills et al.) and 39 healthy individuals. Macular segments' thickness and superficial and deep plexus vascular density (VD) were obtained using spectral-domain OCT and OCTA, respectively. One-way analysis of variance (ANOVA) was used to compare healthy controls and glaucoma patients according to their glaucoma stage. Using correlation analyses, the association between glaucoma and either OCT or OCTA parameters was evaluated. A glaucoma stage-stratified linear regression analysis was then performed. Inner macular segment and whole retinal thickness were reduced in GS1 and GS2 patients compared to healthy controls (e.g., ganglion cell layer GCL: controls: 47.9 ± 7.4, GS1: 45.8 ± 5.1, GS2: 30.6 ± 9.4, ANOVA: p < 0.0001). Regarding OCTA-parameters, the VD of both segmentation levels was reduced in glaucoma patients, particularly when comparing GS2 patients with controls (superficial plexus: p = 0.004) and GS2 with GS1 (p = 0.0008). Linear regression revealed an association between these parameters and the presence of glaucoma (for superior plexus: R2 = 0.059, p = 0.043). Finally, a correlation between macular segment thickness and VD was observed, but with a strength increasing with glaucoma severity (GCL and superior plexus VD: controls: R2 = 0.23, GS1 R2 = 0.40, GS2 R2 = 0.76). Despite the glaucoma-independent correlation between macular segment thickness and VD, disease severity strengthens this correlation. This consideration suggests that glaucoma directly influences OCT and OCTA parameters individually.

Measures of disease activity in glaucoma

Glaucoma is the leading cause of irreversible blindness globally which significantly affects the quality of life and has a substantial economic impact. Effective detective methods are necessary to identify glaucoma as early as possible. Regular eye examinations are important for detecting the disease early and preventing deterioration of vision and quality of life. Current methods of measuring disease activity are powerful in describing the functional and structural changes in glaucomatous eyes. However, there is still a need for a novel tool to detect glaucoma earlier and more accurately. Tear fluid biomarker analysis and new imaging technology provide novel surrogate endpoints of glaucoma. Artificial intelligence is a post-diagnostic tool that can analyse ophthalmic test results. A detail review of currently used clinical tests in glaucoma include intraocular pressure test, visual field test and optical coherence tomography are presented. The advanced technologies for glaucoma measurement which can identify specific disease characteristics, as well as the mechanism, performance and future perspectives of these devices are highlighted. Applications of AI in diagnosis and prediction in glaucoma are mentioned. With the development in imaging tools, sensor technologies and artificial intelligence, diagnostic evaluation of glaucoma must assess more variables to facilitate earlier diagnosis and management in the future.

Non-invasive electrophysiology in glaucoma, structure and function-a review

Glaucoma, its early diagnosis, and monitoring of interventions remain an ongoing challenge. We here review developments in functional assessment and its relation to morphology, evaluating recent insights in electrophysiology in glaucoma and highlighting how glaucoma research and diagnostics benefit from combined approaches of OCT and electrophysiological investigations. After concise overviews of OCT and non-invasive electrophysiology in glaucoma, we evaluate commonalities and complementarities of OCT and electrophysiology for our understanding of glaucoma. As a specific topic, the dynamic range (floor effects) of the various techniques is discussed.

What can visual electrophysiology tell about possible visual-field defects in paediatric patients

Recognising a potential visual-field (VF) defect in paediatric patients might be challenging, especially in children before the age of 5 years and those with developmental delay or intellectual disability. Visual electrophysiological testing is an objective and non-invasive technique for evaluation of visual function in paediatric patients, which can characterise the location of dysfunction and differentiate between disorders of the retina, optic nerve and visual pathway. The recording of electroretinography (ERG) and visual-evoked potentials (VEP) is possible from early days of life and requires no subjective input from the patient. As the origins of ERG and VEP tests are known, the pattern of electrophysiological changes can provide information about the VF of a child unable to perform accurate perimetry. This review summarises previously published electrophysiological findings in several common types of VF defects that can be found in paediatric patients (generalised VF defect, peripheral VF loss, central scotoma, bi-temporal hemianopia, altitudinal VF defect, quadrantanopia and homonymous hemianopia). It also shares experience on using electrophysiological testing as additional functional evidence to other tests in the clinical challenge of diagnosing or excluding VF defects in complex paediatric patients. Each type of VF defect is illustrated with one or two clinical cases.

A Bibliometric and Mapping Analysis of Glaucoma Research between 1900 and 2019

PURPOSE

To explore the relevance of scientific production on glaucoma using bibliometric tools.

DESIGN

Bibliographic study.

PARTICIPANTS

Original articles published from 1900 through 2019.

METHODS

We performed a search in Web of Science for documents published between 1900 and 2019. We used bibliometric indicators to explore documents production, dispersion, distribution, time of duplication, and annual growth, as characterized by Price's law of scientific literature growth, Lotka's law, the transient index, and the Bradford model. We also calculated the participation index of different countries and institutions. Finally, we explored with bibliometric mapping the co-occurrence networks for the most frequently used terms in glaucoma research.

MAIN OUTCOME MEASURES

Bibliometric indicators for individuals, institutions, and countries.

RESULTS

A total of 33 631 original articles were collected from the timeframe 1900 through 2019. Price's law showed an exponential growth. Scientific production was adjusted better to exponential growth (r = 0.967) than linear growth (r = 0.755). Literature on glaucoma research increased its growth in the last 30 years at a rate of 5.1% per year with a production that doubled its size every 13.9 years. The transience index was 60.08%; this indicates that most of the scientific production is the output of very few authors. Bradford's law showed a high concentration of articles published in a small core of specialized journals. Lotka's law indicated that the distribution of authors is concentrated heavily in small producers. The United States and University of London demonstrated the highest production of original articles. Map network visualization showed the generated term map detailing clusters of closely related terms.

CONCLUSIONS

Glaucoma literature has grown exponentially. A very high rate of transience was found that indicates the presence of numerous authors who sporadically publish on this topic. No evidence of a saturation point in the glaucoma literature was observed.

Risk Factors for the Structural Progression of Myopic Glaucomatous Eyes with a History of Laser Refractive Surgery

As laser refractive surgeries (LRS) have been widely performed to correct myopia, ophthalmologists easily encounter patients with glaucoma who have a history of LRS. It is well known that intraocular pressure (IOP) in eyes with glaucoma is not accurate when measured using Goldmann applanation tonometry. However, risk factors for glaucoma progression, particularly those associated with measured IOP, have rarely been studied. We analysed data for 40 patients with a history of LRS and 50 age-matched patients without a history of LRS. Structural progression was defined as significant changes in thickness in the peripapillary retinal nerve fibre layer as identified using optical coherence tomography event-based guided progression analysis. Risk factors were determined via Cox regression analysis. Disc haemorrhage (DH) was associated with glaucoma progression in both the non-LRS group and LRS group (hazard ratio (HR): 4.650, p = 0.012 and HR: 8.666, p = 0.019, respectively). However, IOP fluctuation was associated with glaucoma progression only in the LRS group (HR: 1.452, p = 0.023). Our results show that DH was a significant sign of progression in myopic glaucoma eyes. When treating patients with myopia and glaucoma, IOP fluctuation should be monitored more carefully, even if IOP seems to be well controlled.

Time Lag Between Functional Change and Loss of Retinal Nerve Fiber Layer in Glaucoma

Purpose

It is often suggested that structural change is detectable before functional change in glaucoma. However, this may be related to the lower variability and hence narrower normative limits of structural tests. In this study, we ask whether a time lag exists between the true rates of change in structure and function, regardless of clinical detectability of those changes.

Methods

Structural equation models were used to determine whether the rate of change in function (mean linearized total deviation, AveTDLin) or structure (retinal nerve fiber layer thickness [RNFLT]) was predicted by the concurrent or previous rate for the other modality, after adjusting for its own rate in the previous time interval. Rates were calculated over 1135 pairs of consecutive visits from 318 eyes of 164 participants in the Portland Progression Project, with mean 207 days between visits.

Results

The rate of change of AveTDLin was predicted by its own rate in the previous time interval, but not by rates of RNFLT change in either the concurrent or previous time interval (both P > 0.05). Similarly, the rate of RNFLT change was not predicted by concurrent AveTDLin change after adjusting for its own previous rate. However, the rate of AveTDLin change in the previous time interval did significantly improve prediction of the current rate for RNFLT, with P = 0.005, suggesting a time lag of around six months between changes in AveTDLin and RNFLT.

Conclusions

Although RNFL thinning may be detectable sooner, true functional change appears to predict and precede thinning of the RNFL in glaucoma.

The Effect of Age on Increasing Susceptibility to Retinal Nerve Fiber Layer Loss in Glaucoma

Purpose

To determine whether aging modifies the effect of intraocular pressure (IOP) on progressive glaucomatous retinal nerve fiber layer (RNFL) thinning over time.

Methods

This was a retrospective cohort study involving patients with glaucoma or suspected of having glaucoma who were followed over time from the Duke Glaucoma Registry. Rates of RNFL loss from spectral-domain optical coherence tomography (SD-OCT) were used to assess disease progression. Generalized estimating equations with robust sandwich variance estimators were used to investigate the effects of the interaction of age at baseline and mean IOP on rates of RNFL loss over time. Models were adjusted for gender, race, diagnosis, central corneal thickness, follow-up time, and baseline disease severity.

Results

The study included 85,475 IOP measurements and 60,026 SD-OCT tests of 14,739 eyes of 7814 patients. Eyes had a mean follow-up time of 3.5 ± 1.9 years. The average rate of change in RNFL thickness was –0.70 µm/year (95% confidence interval, –0.72 to –0.67). There was a significant interaction between age and mean IOP and the rate of RNFL loss (P = 0.001), with older eyes having significantly faster rates of RNFL loss than younger ones for the same level of IOP. The effect of IOP on rates of change was greater in the inferior and superior regions of the optic disc.

Conclusions

Age is a significant modifier of the relationship between IOP and glaucomatous loss in RNFL thickness over time. Older patients may be more susceptible to glaucomatous progression than younger patients at the same level of IOP.

Predicting Glaucoma Development With Longitudinal Deep Learning Predictions From Fundus Photographs

PURPOSE

To assess whether longitudinal changes in a deep learning algorithm's predictions of retinal nerve fiber layer (RNFL) thickness based on fundus photographs can predict future development of glaucomatous visual field defects.

DESIGN

Retrospective cohort study.

METHODS

This study included 1,072 eyes of 827 glaucoma-suspect patients with an average follow-up of 5.9 ± 3.8 years. All eyes had normal standard automated perimetry (SAP) at baseline. Additional SAP and fundus photographs were acquired throughout follow-up. Conversion to glaucoma was defined as repeatable glaucomatous defects on SAP. An OCT-trained deep learning algorithm (machine to machine, M2M) was used to predict RNFL thicknesses from fundus photographs. Joint longitudinal survival models were used to assess whether baseline and longitudinal change in M2M's RNFL thickness estimates could predict development of visual field defects.

RESULTS

A total of 196 eyes (18%) converted to glaucoma during follow-up. The mean rate of change in M2M's predicted RNFL thickness was -1.02 μm/y for converters and -0.67 μm/y for non-converters (P < .001). Baseline and rate of change of predicted RNFL thickness were significantly predictive of conversion to glaucoma, with hazard ratios in the multivariable model of 1.56 per 10 μm lower at baseline (95% CI, 1.33-1.82; P < .001) and 1.99 per 1 μm/y faster loss in thickness during follow-up (95% CI, 1.36-2.93; P < .001).

CONCLUSION

Longitudinal changes in a deep learning algorithm's predictions of RNFL thickness measurements based on fundus photographs can be used to predict risk of glaucoma conversion in eyes suspected of having the disease.

Ageing and glaucoma progression of the retinal nerve fibre layer using spectral-domain optical coherence tomography analysis

PURPOSE

To compare the effects of ageing and glaucoma progression on the thickness of the circumpapillary retinal nerve fibre layer (cpRNFL) and to evaluate the performance of a set of optical coherence tomography (OCT) progression analyses.

METHODS

The cpRNFL was measured twice by OCT at each of two visits made 10 years apart in 69 healthy individuals and 49 glaucoma patients. Both visits also included Humphrey 24-2 SITA standard testing. The change in cpRNFL thickness was analysed by linear regression, and a sub-analysis was performed on glaucoma patients with a perimetric mean deviation better than -10 dB at the first visit. The proportion of individuals whose OCT progression analyses indicated progression was also evaluated for the same groups.

RESULTS

The average cpRNFL thickness deteriorated by a mean of -0.16 μm/year in the healthy cohort, increased by 0.03 μm/year in the glaucoma cohort, and deteriorated by -0.24 μm/year in eyes with less severe glaucoma; there were no statistically significant differences between the groups. For 17 (30%) of 56 healthy individuals, at least one of the three different OCT progression analyses incorrectly indicated progression.

CONCLUSIONS

No significant differences in change of cpRNFL thickness between visits were found when comparing healthy subjects with glaucoma patients. Also, further cpRNFL thinning was not observed in glaucomatous eyes in which at least one-third of the visual field had been lost. The OCT progression analyses generated a relatively high proportion of false positives. Using OCT for glaucoma follow-up may not be entirely straightforward.

Apoptosis in health and diseases of the eye and brain

Apoptosis is a form of programmed cell death (PCD) and enables the immunologically silent disposal of senescent or unwanted cells, causing minimal damage to the surrounding environment. Apoptosis can occur via intrinsic or extrinsic pathways that initiate a series of intracellular and extracellular signaling events. This ultimately leads to the clearance of the cell by phagocytes. This normal physiological mechanism may be accelerated in several diseases including those involving the eyes and brain, leading to loss of structure and function. This review presents the role of PCD in the health of the eyes and brain, and the evidence presented for its aberrant role in disease.

Recent developments in the use of optical coherence tomography for glaucoma

PURPOSE OF REVIEW

The aim of this article is to summarize findings of recent reports highlighting the utility of novel optical coherence tomography (OCT) parameters in the diagnosis and monitoring of glaucomatous optic neuropathy.

RECENT FINDINGS

Optic nerve head (ONH), retinal nerve fiber layer (RNFL), and macular parameters show high levels of diagnostic capability. The Bruch's membrane opening-minimum rim width (BMO-MRW) measurement is a novel ONH parameter obtained using the Spectralis SD-OCT device (Heidelberg Engineering, Inc., Heidelberg, Germany). The inferotemporal BMO-MRW sector shows the highest diagnostic performance for this parameter. Minimum ganglion cell and inner plexiform layer thickness shows the highest diagnostic performance among macular parameters obtained with the Cirrus HD-OCT (Carl Zeiss, Inc., Dublin, CA, USA). Optic nerve head, macular, and retinal nerve fiber layer parameters are not interchangeable across protocols generated by varying OCT manufacturers. Novel machine-learning algorithms show promise with regards to achieving higher levels of diagnostic accuracy using OCT imaging platforms.

SUMMARY

Digital imaging in glaucoma continues to evolve with novel parameters of the optic nerve head, retinal nerve fiber layer, and macula. Diagnostic abilities of these parameters are high and complementary to each other.

A simplified combined index of structure and function for detecting and staging glaucomatous damage

Glaucomatous damage results in characteristics structural and functional changes on optical coherence tomography (OCT) imaging and standard automated perimetry (SAP) testing. The clinical utility of these measures differs based on disease severity, as they are evaluated along different measurement scales. This study therefore sought to examine if a simplified combined structure-function index (sCSFI) could improve the detection and staging of glaucomatous damage, compared to the use of average retinal nerve fiber layer thickness (RNFL) measurements from OCT and mean deviation (MD) values from SAP alone, and also an estimated retinal ganglion cell counts (eRGC) measure derived using empirical formulas described previously. Examining 577 eyes from 354 participants with perimetric glaucoma and 241 normal eyes from 138 healthy participants, we found that the sCSFI performed significantly better than average RNFL, MD and eRGC count for discriminating between glaucoma and healthy eyes (P ≤ 0.008 for all). The sCSFI also performed significantly better than RNFL and eRGC count at discriminating between different levels of visual field damage in glaucoma eyes (P < 0.001 for both). These findings highlight the clinical utility of combining structural and functional information for detecting and staging glaucomatous damage using the simplified index developed in this study.

Risk Factors Associated with Structural Progression in Normal-Tension Glaucoma: Intraocular Pressure, Systemic Blood Pressure, and Myopia

Purpose

To determine risk factors associated with structural progression in medically treated normal-tension glaucoma (NTG).

Methods

This retrospective cohort study included 166 NTG patients (average age, 56.5 years; average mean deviation, −4.2 dB). The structural progression endpoint was determined by optical coherence tomography; significant thickness differences in the peripapillary retinal nerve fiber layer (RNFL) or macular ganglion cell inner plexiform layer (GCIPL) that exceeded baseline test-retest variability were identified with event-based guided-progression analysis. Intraocular pressure and systemic blood pressure (BP) were measured at each visit throughout the follow-up period, and the risk for progression was evaluated with Cox regression. Myopic disc features and antihypertensives were also analyzed. Tree analysis was used to determine the cutoff values and elucidate influential risk factors.

Results

Structural progression, defined as progressive peripapillary RNFL or macular GCIPL thinning, was identified in 62 eyes. Occurrence of disc hemorrhages, presence of diabetes, and lower minimum systolic BP were associated with progression (hazard ratio [HR]: 2.116, P = 0.005; HR: 1.998, P = 0.031; HR: 0.968, P = 0.005; respectively). The cutoff value derived from the tree analysis of minimum systolic BP was 108 mm Hg. The tree analysis revealed systolic and diastolic BP to be the most influential risk factors for progressive peripapillary RFNL thinning and progressive macular GCIPL thinning, respectively.

Conclusions

Low BP measured during follow-up correlated with structural progression in medically treated NTG eyes, indicating that the evaluation of hypotension is required during the management of NTG patients. The tree analysis identified BP target values that may help prevent glaucoma progression.

Ganglion cell layer analysis with deep learning in glaucoma diagnosis

OBJECTIVE

To determine and compare the diagnostic precision in glaucoma of two deep learning models using infrared images of the optic nerve, eye fundus, and the ganglion cell layer (GCL).

METHODS

We have selected a sample of normal and glaucoma patients. Three infrared images were registered with a spectral-domain optical coherence tomography (SD-OCT). The first corresponds to the confocal scan image of the fundus, the second is a cut-out of the first centered on the optic nerve, and the third was the SD-OCT image of the GCL. Our deep learning models are developed on the MatLab platform with the ResNet50 and VGG19 pre-trained neural networks.

RESULTS

498 eyes of 298 patients were collected. Of the 498 eyes, 312 are glaucoma and 186 are normal. In the test, the precision of the models was 96% (ResNet50) and 96% (VGG19) for the GCL images, 90% (ResNet50) and 90% (VGG19) for the optic nerve images and 82% (ResNet50) and 84% (VGG19) for the fundus images. The ROC area in the test was 0.96 (ResNet50) and 0.97 (VGG19) for the GCL images, 0.87 (ResNet50) and 0.88 (VGG19) for the optic nerve images, and 0.79 (ResNet50) and 0.81 (VGG19) for the fundus images.

CONCLUSIONS

Both deep learning models, applied to the GCL images, achieve high diagnostic precision, sensitivity and specificity in the diagnosis of glaucoma.

Applications of deep learning in detection of glaucoma: A systematic review

Glaucoma is the leading cause of irreversible blindness and disability worldwide. Nevertheless, the majority of patients do not know they have the disease and detection of glaucoma progression using standard technology remains a challenge in clinical practice. Artificial intelligence (AI) is an expanding field that offers the potential to improve diagnosis and screening for glaucoma with minimal reliance on human input. Deep learning (DL) algorithms have risen to the forefront of AI by providing nearly human-level performance, at times exceeding the performance of humans for detection of glaucoma on structural and functional tests. A succinct summary of present studies and challenges to be addressed in this field is needed. Following PRISMA guidelines, we conducted a systematic review of studies that applied DL methods for detection of glaucoma using color fundus photographs, optical coherence tomography (OCT), or standard automated perimetry (SAP). In this review article we describe recent advances in DL as applied to the diagnosis of glaucoma and glaucoma progression for application in screening and clinical settings, as well as the challenges that remain when applying this novel technique in glaucoma.

Detecting apoptosis as a clinical endpoint for proof of a clinical principle

The transparent eye media represent a window through which to observe changes occurring in the retina during pathological processes. In contrast to visualising the extent of neurodegenerative damage that has already occurred, imaging an active process such as apoptosis has the potential to report on disease progression and therefore the threat of irreversible functional loss in various eye and brain diseases. Early diagnosis in these conditions is an important unmet clinical need to avoid or delay irreversible sight loss. In this setting, apoptosis detection is a promising strategy with which to diagnose, provide prognosis, and monitor therapeutic response. Additionally, monitoring apoptosis in vitro and in vivo has been shown to be valuable for drug development in order to assess the efficacy of novel therapeutic strategies both in the pre-clinical and clinical setting. Detection of Apoptosing Retinal Cells (DARC) technology is to date the only tool of its kind to have been tested in clinical trials, with other new imaging techniques under investigation in the fields of neuroscience, ophthalmology and drug development. We summarize the transitioning of techniques detecting apoptosis from bench to bedside, along with the future possibilities they encase.

Optical coherence tomography indices in the diagnosis and discrimination of stages of primary open-angle glaucoma in an African population

PURPOSE

The objective of this study was to determine the structure-function association of the optical coherence tomography (OCT) indices (retinal nerve fibre layer (RNFL), ganglion cell complex (GCC) and optic nerve head (ONH) parameters) with the visual field sensitivity and their diagnostic ability at different stages of primary open-angle glaucoma (POAG) among a population West-African descent.

METHODS

The study was a clinic-based prospective study which employed purposive sampling in the recruitment of clinically diagnosed POAG and non-glaucoma patients. OCT and visual field test (VFT) results were collated. Classification of the POAG cases was done using the Hodapp-Parrish-Anderson criteria. ROC was used for assessing the diagnostic ability of OCT indices. Pearson's correlation was used to assess the structure-function association. P value < 0.05 was considered statistically significant.

CONCLUSIONS

Of the 497 subjects (497 eyes), 301 (60.6%) were males and 196 (39.4%) were females. The average, superior and inferior RNFL and GCC showed a strong positive correlation with the visual field sensitivity, but the average RNFL had the highest correlation (r = 0.673, p < 0.001). The parameters of the ONH showed a moderate-to-weak correlation with the visual field sensitivity. However, there was no significant correlation between structure and function in early POAG (p > 0.05). Superior GCC showed the highest diagnostic ability for POAG (AUC = 0.655; p < 0.001) comparable to the RNFL. Macula (GCC) and (RNFL) have a comparable ability to diagnose POAG at all the stages of POAG and can be used complimentarily for glaucoma assessment and diagnosis.

A 3D model to evaluate retinal nerve fiber layer thickness deviations caused by the displacement of optical coherence tomography circular scans in cynomolgus monkeys (Macaca fascicularis)

The main objective of the study was to analyze deviations in retinal nerve fiber layer (RNFL) thickness measurements caused by the displacement of circular optic disc optical coherence tomography scans. High-density radial scans of the optic nerve heads of cynomolgus monkeys were acquired. The retinal nerve fiber layer was manually segmented, and a surface plot of the discrete coordinates was generated. From this plot, the RNFL thicknesses were calculated and compared between accurately centered and intentionally displaced circle scans. Circle scan displacement caused circumpapillary retinal nerve fiber layer thickness deviations of increasing magnitude with increasing center offset. As opposed to the human eye, horizontal displacement resulted in larger RNFL thickness deviations than vertical displacement in cynomolgus monkeys. Acquisition of high-density radial scans allowed for the mathematical reconstruction and modelling of the nerve fiber layer and extrapolation of its thickness. Accurate and strictly repeatable circle scan placement is critical to obtain reproducible values, which is essential for longitudinal studies.

Attention-Guided 3D-CNN Framework for Glaucoma Detection and Structural-Functional Association Using Volumetric Images

The direct analysis of 3D Optical Coherence Tomography (OCT) volumes enables deep learning models (DL) to learn spatial structural information and discover new bio-markers that are relevant to glaucoma. Downsampling 3D input volumes is the state-of-art solution to accommodate for the limited number of training volumes as well as the available computing resources. However, this limits the network's ability to learn from small retinal structures in OCT volumes. In this paper, our goal is to improve the performance by providing guidance to DL model during training in order to learn from finer ocular structures in 3D OCT volumes. Therefore, we propose an end-to-end attention guided 3D DL model for glaucoma detection and estimating visual function from retinal structures. The model consists of three pathways with the same network architecture but different inputs. One input is the original 3D-OCT cube and the other two are computed during training guided by the 3D gradient class activation heatmaps. Each pathway outputs the class-label and the whole model is trained concurrently to minimize the sum of losses from three pathways. The final output is obtained by fusing the predictions of the three pathways. Also, to explore the robustness and generalizability of the proposed model, we apply the model on a classification task for glaucoma detection as well as a regression task to estimate visual field index (VFI) (a value between 0 and 100). A 5-fold cross-validation with a total of 3782 and 10,370 OCT scans is used to train and evaluate the classification and regression models, respectively. The glaucoma detection model achieved an area under the curve (AUC) of 93.8% compared with 86.8% for a baseline model without the attention-guided component. The model also outperformed six different feature based machine learning approaches that use scanner computed measurements for training. Further, we also assessed the contribution of different retinal layers that are relevant to glaucoma. The VFI estimation model achieved a Pearson correlation and median absolute error of 0.75 and 3.6%, respectively, for a test set of size 3100 cubes.

Detection of Progressive Glaucomatous Optic Nerve Damage on Fundus Photographs with Deep Learning

Purpose

To investigate whether predictions of retinal nerve fiber layer (RNFL) thickness obtained from a deep learning model applied to fundus photographs can detect progressive glaucomatous changes over time.

Design

Retrospective cohort study.

Participants

Eighty-six thousand one hundred twenty-three pairs of color fundus photographs and spectral-domain (SD) OCT images collected during 21 232 visits from 8831 eyes of 5529 patients with glaucoma or glaucoma suspects.

Methods

A deep learning convolutional neural network was trained to assess fundus photographs and to predict SD OCT global RNFL thickness measurements. The model then was tested on an independent sample of eyes that had longitudinal follow-up with both fundus photography and SD OCT. The ability to detect eyes that had statistically significant slopes of SD OCT change was assessed by receiver operating characteristic (ROC) curves. The repeatability of RNFL thickness predictions was investigated by measurements obtained from multiple photographs that had been acquired during the same day.

Main Outcome Measures

The relationship between change in predicted RNFL thickness from photographs and change in SD OCT RNFL thickness over time.

Results

The test sample consisted of 33 466 pairs of fundus photographs and SD OCT images collected during 7125 visits from 1147 eyes of 717 patients. Eyes in the test sample were followed up for an average of 5.3 ± 3.3 years, with an average of 6.2 ± 3.8 visits. A significant correlation was found between change over time in predicted and observed RNFL thickness (r = 0.76; 95% confidence interval [CI], 0.70–0.80; P < 0.001). Retinal nerve fiber layer predictions showed an ROC curve area of 0.86 (95% CI, 0.83–0.88) to discriminate progressors from nonprogressors. For detecting fast progressors (slope faster than 2 μm/year), the ROC curve area was 0.96 (95% CI, 0.94–0.98), with a sensitivity of 97% for 80% specificity and 85% for 90% specificity. For photographs obtained at the same visit, the intraclass correlation coefficient was 0.946 (95% CI, 0.940–0.952), with a coefficient of variation of 3.2% (95% CI, 3.1%–3.3%).

Conclusions

A deep learning model was able to obtain objective and quantitative estimates of RNFL thickness that correlated well with SD OCT measurements and potentially could be used to monitor for glaucomatous changes over time.