The structure and function relationship in glaucoma: implications for detection of progression and measurement of rates of change

Prediction of visual field progression with serial optic disc photographs using deep learning

AIM

We tested the hypothesis that visual field (VF) progression can be predicted with a deep learning model based on longitudinal pairs of optic disc photographs (ODP) acquired at earlier time points during follow-up.

METHODS

3919 eyes (2259 patients) with ≥2 ODPs at least 2 years apart, and ≥5 24-2 VF exams spanning ≥3 years of follow-up were included. Serial VF mean deviation (MD) rates of change were estimated starting at the fifth visit and subsequently by adding visits until final visit. VF progression was defined as a statistically significant negative slope at two consecutive visits and final visit. We built a twin-neural network with ResNet50-backbone. A pair of ODPs acquired up to a year before the VF progression date or the last VF in non-progressing eyes were included as input. Primary outcome measures were area under the receiver operating characteristic curve (AUC) and model accuracy.

RESULTS

The average (SD) follow-up time and baseline VF MD were 8.1 (4.8) years and -3.3 (4.9) dB, respectively. VF progression was identified in 761 eyes (19%). The median (IQR) time to progression in progressing eyes was 7.3 (4.5-11.1) years. The AUC and accuracy for predicting VF progression were 0.862 (0.812-0.913) and 80.0% (73.9%-84.6%). When only fast-progressing eyes were considered (MD rate < -1.0 dB/year), AUC increased to 0.926 (0.857-0.994).

CONCLUSIONS

A deep learning model can predict subsequent glaucoma progression from longitudinal ODPs with clinically relevant accuracy. This model may be implemented, after validation, for predicting glaucoma progression in the clinical setting.

Rates of retinal nerve fiber layer loss in early-stage pseudoexfoliation and primary open-angle glaucoma patients using optical coherence tomography

PURPOSE

To characterize glaucoma progression in early-stage patients with retinal nerve fiber layer (RNFL) using the change analysis software (CAS), which was utilized to track RNFL thinning.

METHODS

We retrospectively analyzed 92 eyes of 92 patients with early-stage glaucoma. Patients were divided into two subgroups based on their diagnosis of pseudoexfoliation glaucoma (PEG) and primary open-angle glaucoma (POAG). A complete ophthalmologic examination was performed on all patients. Additionally, automated perimetry was conducted on each patient. Furthermore, Fourier-domain optical coherence tomography (OCT) was employed to measure RNFL and central corneal thickness. Using the OCT device's CAS, we computed the annual rate of total and glaucomatous RNFL thinning for each patient.

RESULTS

A total of 44 PEG and 48 POAG patients were included in the study. The right eye measurements of these patients were analyzed and compared. The two groups were not significantly different in age, gender, and the number of visits per year (p > 0.05, for each). However, the difference between the mean RNFL thickness at baseline (91.39 ± 10.71 and 96.9 ± 8.6 µm) and at the last visit (85.2 ± 15.76 µm and 91.56 ± 9.58 µm) was statistically significant between the two groups (p = 0.043, p = 0.039, respectively). Additionally, the difference in annual RNFL thinning rates (1.43 ± 0.81 µm and 1.07 ± 0.32 µm) between the two groups was statistically significant (p = 0.009).

CONCLUSION

The annual rate of glaucomatous RNFL loss in early-stage PEG patients (1.23 µm) was higher than in POAG patients (0.87 µm). However, despite these loss rates, scotoma was not detected in the visual field tests of these patients. Therefore, using CAS in the follow-up of early-stage glaucoma patients is a useful alternative for monitoring glaucomatous progression. Furthermore, this method can be utilized in future research for the diagnosis and follow-up of glaucoma in special populations (e.g., those with pathological myopia or high hyperopia) that are not included in normative databases.

The Impact of Achieving Target Intraocular Pressure on Glaucomatous Retinal Nerve Fiber Layer Thinning in a Treated Clinical Population

PURPOSE

To estimate the effect of being below and above the clinician-set target intraocular pressure (IOP) on rates of glaucomatous retinal nerve fiber layer (RNFL) thinning in a treated real-world clinical population.

DESIGN

Retrospective cohort study.

METHODS

A total of 3256 eyes (1923 patients) with ≥5 reliable optical coherence tomography scans and 1 baseline visual field test were included. Linear mixed-effects modeling estimated the effects of the primary independent variables (mean target difference [measured IOP - target IOP] and mean IOP, mm Hg) on the primary dependent variable (RNFL slope, µm/y) while accounting for additional confounding variables (age, biological sex, race, baseline RNFL, baseline pachymetry, and disease severity). A spline term accounted for differential effects when above (target difference >0 mm Hg) and below (target difference ≤0 mm Hg) target pressure.

RESULTS

Eyes below and above target had significantly different mean RNFL slopes (-0.44 vs -0.71 µm/y, P < .001). Each 1 mm Hg increase above target had a 0.143 µm/y faster rate of RNFL thinning (P < .001). Separating by disease severity, suspect, mild, moderate, and advanced glaucoma had 0.135 (P = .002), 0.116 (P = .009), 0.203 (P = .02), and 0.65 (P = .22) µm/y faster rates of RNFL thinning per 1 mm Hg increase, respectively.

CONCLUSIONS

Being above the clinician-set target pressure is associated with more rapid RNFL thinning in suspect, mild, and moderate glaucoma. Faster rates of thinning were also present in advanced glaucoma, but statistical significance was limited by the lower sample size of eyes above target and the optical coherence tomography floor effect.

Short-term Detection of Fast Progressors in Glaucoma: The Fast Progression Assessment through Clustered Evaluation (Fast-PACE) Study

PURPOSE

To evaluate the performance of an intensive, clustered testing approach in identifying eyes with rapid glaucoma progression over 6 months in the Fast Progression Assessment through Clustered Evaluation (Fast-PACE) Study.

DESIGN

Prospective cohort study.

PARTICIPANTS

A total of 125 eyes from 65 primary open-angle glaucoma (POAG) subjects.

METHODS

Subjects underwent 2 sets of 5 weekly visits (clusters) separated by an average of 6 months and then were followed with single visits every 6 months for an overall mean follow-up of 25 months (mean of 17 tests). Each visit consisted of testing with standard automated perimetry (SAP) 24-2 and 10-2, and spectral-domain OCT (SD-OCT). Progression was assessed using trend analyses of SAP mean deviation (MD) and retinal nerve fiber layer (RNFL) thickness. Generalized estimating equations were applied to adjust for correlations between eyes for confidence interval (CI) estimation and hypothesis testing.

MAIN OUTCOME MEASURES

Diagnostic accuracy of the 6-month clustering period to identify progression detected during the overall follow-up.

RESULTS

A total of 19 of 125 eyes (15%, CI, 9%-24%) progressed based on SAP 24-2 MD over the 6-month clustering period. A total of 14 eyes (11%, CI, 6%-20%) progressed on SAP 10-2 MD, and 16 eyes (13%, CI, 8%-21%) progressed by RNFL thickness, with 30 of 125 eyes (24%, CI, 16%-34%) progressing by function, structure, or both. Of the 35 eyes progressing during the overall follow-up, 25 had progressed during the 6-month clustering period, for a sensitivity of 71% (CI, 53%-85%). Of the 90 eyes that did not progress during the overall follow-up, 85 also did not progress during the 6-month period, for a specificity of 94% (CI, 88%-98%). Of the 14 eyes considered fast progressors by SAP 24-2, SAP 10-2, or SD-OCT during the overall follow-up, 13 were identified as progressing during the 6-month cluster period, for a sensitivity of 93% (CI, 66%-100%) for identifying fast progression with a specificity of 85% (CI, 77%-90%).

CONCLUSIONS

Clustered testing in the Fast-PACE Study detected fast-progressing glaucoma eyes over 6 months. The methodology could be applied in clinical trials investigating interventions to slow glaucoma progression and may be of value for short-term assessment of high-risk subjects.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references in the Footnotes and Disclosures at the end of this article.

Automated Classification of Physiologic, Glaucomatous, and Glaucoma-Suspected Optic Discs Using Machine Learning

In order to generate a machine learning algorithm (MLA) that can support ophthalmologists with the diagnosis of glaucoma, a carefully selected dataset that is based on clinically confirmed glaucoma patients as well as borderline cases (e.g., patients with suspected glaucoma) is required. The clinical annotation of datasets is usually performed at the expense of the data volume, which results in poorer algorithm performance. This study aimed to evaluate the application of an MLA for the automated classification of physiological optic discs (PODs), glaucomatous optic discs (GODs), and glaucoma-suspected optic discs (GSODs). Annotation of the data to the three groups was based on the diagnosis made in clinical practice by a glaucoma specialist. Color fundus photographs and 14 types of metadata (including visual field testing, retinal nerve fiber layer thickness, and cup-disc ratio) of 1168 eyes from 584 patients (POD = 321, GOD = 336, GSOD = 310) were used for the study. Machine learning (ML) was performed in the first step with the color fundus photographs only and in the second step with the images and metadata. Sensitivity, specificity, and accuracy of the classification of GSOD vs. GOD and POD vs. GOD were evaluated. Classification of GOD vs. GSOD and GOD vs. POD performed in the first step had AUCs of 0.84 and 0.88, respectively. By combining the images and metadata, the AUCs increased to 0.92 and 0.99, respectively. By combining images and metadata, excellent performance of the MLA can be achieved despite having only a small amount of data, thus supporting ophthalmologists with glaucoma diagnosis.

Performance of Linear Mixed Models in Estimating Structural Rates of Glaucoma Progression Using Varied Random Effect Distributions

Purpose

To compare how linear mixed models (LMMs) using Gaussian, Student t, and log-gamma (LG) random effect distributions estimate rates of structural loss in a glaucomatous population using OCT and to compare model performance to ordinary least squares (OLS) regression.

Design

Retrospective cohort study.

Subjects

Patients in the Bascom Palmer Glaucoma Repository (BPGR).

Methods

Eyes with ≥ 5 reliable peripapillary retinal nerve fiber layer (RNFL) OCT tests over ≥ 2 years were identified from the BPGR. Retinal nerve fiber layer thickness values from each reliable test (signal strength ≥ 7/10) and associated time points were collected. Data were modeled using OLS regression as well as LMMs using different random effect distributions. Predictive modeling involved constructing LMMs with (n - 1) tests to predict the RNFL thickness of subsequent tests. A total of 1200 simulated eyes of different baseline RNFL thickness values and progression rates were developed to evaluate the likelihood of declared progression and predicted rates.

Main Outcome Measures

Model fit assessed by Watanabe-Akaike information criterion (WAIC) and mean absolute error (MAE) when predicting future RNFL thickness values; log-rank test and median time to progression with simulated eyes.

Results

A total of 35 862 OCT scans from 5766 eyes of 3491 subjects were included. The mean follow-up period was 7.0 ± 2.3 years, with an average of 6.2 ± 1.4 tests per eye. The Student t model produced the lowest WAIC. In predictive models, all LMMs demonstrated a significant reduction in MAE when estimating future RNFL thickness values compared with OLS (P < 0.001). Gaussian and Student t models were similar and significantly better than the LG model in estimating future RNFL thickness values (P < 0.001). Simulated eyes confirmed LMM performance in declaring progression sooner than OLS regression among moderate and fast progressors (P < 0.01).

Conclusions

LMMs outperformed conventional approaches for estimating rates of OCT RNFL thickness loss in a glaucomatous population. The Student t model provides the best model fit for estimating rates of change in RNFL thickness, although the use of the Gaussian or Student t distribution in models led to similar improvements in accurately estimating RNFL loss.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

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.

Prediction and Detection of Glaucomatous Visual Field Progression Using Deep Learning on Macular Optical Coherence Tomography

PRCIS

A deep learning model trained on macular OCT imaging studies detected clinically significant functional glaucoma progression and was also able to predict future progression.

OBJECTIVE

To use macular optical coherence tomography (OCT) imaging to predict the future and detect concurrent visual field progression, respectively, using deep learning.

DESIGN

A retrospective cohort study.

SUBJECTS

A pretraining data set was comprised of 7,702,201 B-scan images from 151,389 macular OCT studies. The progression detection task included 3902 macular OCT imaging studies from 1534 eyes of 828 patients with glaucoma, and the progression prediction task included 1346 macular OCT studies from 1205 eyes of 784.

METHODS

A novel deep learning method was developed to detect glaucoma progression and predict future progression using macular OCT, based on self-supervised pretraining of a vision transformer (ViT) model on a large, unlabeled data set of OCT images. Glaucoma progression was defined as a mean deviation (MD) rate of change of ≤ -0.5 dB/year over 5 consecutive Humphrey visual field tests, and rapid progression was defined as MD change ≤ -1 dB/year.

MAIN OUTCOME MEASURES

Diagnostic performance of the ViT model for prediction of future visual field progression and detection of concurrent visual field progression using area under the receiver operating characteristic curve (AUC), sensitivity, and specificity.

RESULTS

The model distinguished stable eyes from progressing eyes, achieving an AUC of 0.90 (95% CI, 0.88-0.91). Rapid progression was detected with an AUC of 0.92 (95% CI, 0.91-0.93). The model also demonstrated high predictive ability for forecasting future glaucoma progression, with an AUC of 0.85 (95% CI 0.83-0.87). Rapid progression was predicted with an AUC of 0.84 (95% CI 0.81-0.86).

CONCLUSIONS

A deep learning model detected clinically significant functional glaucoma progression using macular OCT imaging studies and was also able to predict future progression. Early identification of patients undergoing glaucoma progression or at high risk for future progression may aid in clinical decision-making.

Using Fused Data from Perimetry and Optical Coherence Tomography to Improve the Detection of Visual Field Progression in Glaucoma

Perimetry and optical coherence tomography (OCT) are both used to monitor glaucoma progression. However, combining these modalities can be a challenge due to differences in data types. To overcome this, we have developed an autoencoder data fusion (AEDF) model to learn compact encoding (AE-fused data) from both perimetry and OCT. The AEDF model, optimized specifically for visual field (VF) progression detection, incorporates an encoding loss to ensure the interpretation of the AE-fused data is similar to VF data while capturing key features from OCT measurements. For model training and evaluation, our study included 2504 longitudinal VF and OCT tests from 140 glaucoma patients. VF progression was determined from linear regression slopes of longitudinal mean deviations. Progression detection with AE-fused data was compared to VF-only data (standard clinical method) as well as data from a Bayesian linear regression (BLR) model. In the initial 2-year follow-up period, AE-fused data achieved a detection F1 score of 0.60 (95% CI: 0.57 to 0.62), significantly outperforming (p < 0.001) the clinical method (0.45, 95% CI: 0.43 to 0.47) and the BLR model (0.48, 95% CI: 0.45 to 0.51). The capacity of the AEDF model to generate clinically interpretable fused data that improves VF progression detection makes it a promising data integration tool in glaucoma management.

Hemifield-based analysis of pattern electroretinography in normal subjects and patients with preperimetric glaucoma

This prospective cross-sectional study investigated the visual function of preperimetric glaucoma (PPG) patients based on hemifield (HF) pattern electroretinogram (PERG) amplitudes. Thirty-two (32) normal subjects and 33 PPG patients were enrolled in control and PPG groups, respectively. All of the participants had undergone full ophthalmic examinations, including spectral-domain optical coherence tomography (SD-OCT), visual field (VF) examination and pattern electroretinography (PERG). The PERG parameters along with the HF ratios of SD-OCT and PERG were compared between the control and PPG groups. Pairwise Pearson's correlation coefficients and linear regression models were fitted to investigate the correlations. The PERG N95 amplitudes were significantly lower in the PPG group (P < 0.001). The smaller/larger HF N95 amplitude ratio of the PPG group was found to be smaller than that of the control group (0.73 ± 0.20 vs. 0.86 ± 0.12; P = 0.003) and showed positive correlations with affected HF average ganglion cell-inner plexiform layer (GCIPL) thickness (r = 0.377, P = 0.034) and with average GCIPL thickness (r = 0.341, P = 0.005). The smaller/larger HF N95 amplitude ratio did not significantly change with age (β =  - 0.005, P = 0.195), whereas the full-field N95 amplitude showed a negative correlation with age (β =  - 0.081, P < 0.001). HF analysis of PERG N95 amplitudes might be particularly useful for patients with early glaucoma.

Genetic risk of glaucoma is associated with vascular and retinal nerve fibre wedge defects

PURPOSE

To evaluate the association between localised vascular and retinal nerve fibre layer (RNFL) loss and genetic risk for glaucoma and cardiovascular disease using polygenic risk scores (PRS).

METHODS

858 eyes were included from 455 individuals with suspect and early manifest primary open angle glaucoma. Eyes were characterised as having localised vascular and/or RNFL wedge-shaped defects by scrutiny of optical coherence tomography angiography (OCTA) and OCT images, respectively. Investigations included associations with pre-established scores for genetic risk of glaucoma and cardiovascular disease in the context of glaucoma risk factors and systemic vascular disease outcomes.

RESULTS

Higher genetic risk for glaucoma was associated with both vascular wedge defects and RNFL defects (p < 0.001 and p = 0.020, respectively). A greater genetic risk of glaucoma was associated with the presence of multiple vascular wedges per eye (p = 0.005). Glaucoma progression based on global RNFL loss was associated with vascular and RNFL wedge defects (p ≤ 0.001 and p = 0.008, respectively). The glaucoma PRS was significantly associated with vascular, but not RNFL, wedge defects after controlling for disc haemorrhage (p = 0.007 and p = 0.070, respectively). Vascular wedge defects were not related to the cardiovascular PRS.

CONCLUSION

Individuals with a higher genetic risk of glaucoma based on the PRS were more likely to have retinal vascular defects, as well as structural glaucomatous loss, but this did not relate to systemic cardiovascular risk. This possibly implies a local pathophysiology for the vascular defects in some cases, which may have clinical relevance in the early stages of glaucoma and in individuals at high genetic risk.

Differentiating stages of functional vision loss from glaucoma using the Disc Damage Likelihood Scale and cup:disc ratio

BACKGROUND

Glaucoma staging is critical for treatment planning but has rarely been tested in severe/end-stage disease. We compared the performance of the Disc Damage Likelihood Scale (DDLS) and cup:disc ratio (CDR) using a functional glaucoma staging system (GSS) as the reference standard.

METHODS

Post hoc analysis of a randomised controlled trial at the Eye Department of Kilimanjaro Christian Medical Centre, Tanzania. Eligible participants (aged ≥18 years) with open-angle glaucoma, intraocular pressure (IOP) of >21 mm Hg, were randomised to timolol 0.5% eye drops or selective laser trabeculoplasty. Fundoscopy established vertical and horizontal CDRs and DDLS. Visual acuity and static visual fields were graded (GSS). The study used area under the receiver operating characteristic (AROC) curves and Spearman's rank correlation coefficients to compare staging systems. Logistic regression with generalised estimating equations determined risk factors of functional severe/end-stage glaucoma.

RESULTS

382 eyes (201 participants) were evaluated; 195 (51%) had severe or end-stage glaucoma; mean IOP was 26.7 (SD 6.9) mm Hg. DDLS yielded an AROC of 0.90 (95% CI 0.87 to 0.93), vertical cup:disc ratio (vCDR) of 0.88 (95% CI 0.85 to 0.91, p=0.048) for identifying severe/end-stage disease. Correlation coefficients comparing GSS to DDLS and vCDRs were 0.73 and 0.71, respectively. Advanced structural stages, vision impairment, higher IOP and less financial resources were risk factors of functional severe/end-stage glaucoma.

CONCLUSION

This study indicates that both structural staging systems can differentiate severe/end-stage glaucoma from less severe disease, with a moderate advantage of DDLS over CDR. Clinical examination of the optic disc plays an important role in addition to functional assessment when managing severe/end-stage glaucoma.

Between-eye correlation of ocular parameters

OBJECTIVE

It is accepted that ocular parameters are more correlated with the fellow eye. This poses a challenge in ophthalmic research. There is a relative scarcity of data concerning the extent of correlation. The aim of this study was to analyze and quantify the correlation of different ocular parameters.

DESIGN

Historical registry analysis.

PARTICIPANTS

All patients examined in a 10-year period (2011-2021) in one academic tertiary medical centre in central Israel.

METHODS

Data from optical coherence tomography examinations and biometry of a single examination of both eyes taken at the same time from each patient was included. Pearson's r values were calculated to estimate the extent of correlation.

RESULTS

A total of 17,212 patients were included. Mean age was 73 ± 12.7 years, and 54.5% were female. All examined parameters were highly statistically significantly correlated between eyes (all with p < 0.1 × 10-36), whereas the strength of correlation differed. Very weak correlation was seen in central macular thickness (r = 0.189), and a weak correlation was seen in anterior-chamber depth (r = 0.379) and retinal nerve fibre layer thickness (r = 0.479). A strong correlation was seen in central corneal thickness (r = 0.754), and a very strong correlation was seen in axial length (r = 0.900).

CONCLUSIONS

In a retrospective analysis of optical coherence tomography and biometry measurements of >10,000 patients, all examined parameters were highly statistically significantly correlated. Correlation magnitude varied, with structural characteristics more correlated than functional ones. Including both eyes in an outcome analysis likely will introduce bias. We recommend adjusting for inter-eye correlation in all studies assessing ocular outcome measures.

A Bayesian Hierarchical Spatial Longitudinal Model Improves Estimation of Local Macular Rates of Change in Glaucomatous Eyes

Purpose

Demonstrate that a novel Bayesian hierarchical spatial longitudinal (HSL) model improves estimation of local macular ganglion cell complex (GCC) rates of change compared to simple linear regression (SLR) and a conditional autoregressive (CAR) model.

Methods

We analyzed GCC thickness measurements within 49 macular superpixels in 111 eyes (111 patients) with four or more macular optical coherence tomography scans and two or more years of follow-up. We compared superpixel-patient-specific estimates and their posterior variances derived from the latest version of a recently developed Bayesian HSL model, CAR, and SLR. We performed a simulation study to compare the accuracy of intercept and slope estimates in individual superpixels.

Results

HSL identified a significantly higher proportion of significant negative slopes in 13/49 superpixels and a significantly lower proportion of significant positive slopes in 21/49 superpixels than SLR. In the simulation study, the median (tenth, ninetieth percentile) ratio of mean squared error of SLR [CAR] over HSL for intercepts and slopes were 1.91 (1.23, 2.75) [1.51 (1.05, 2.20)] and 3.25 (1.40, 10.14) [2.36 (1.17, 5.56)], respectively.

Conclusions

A novel Bayesian HSL model improves estimation accuracy of patient-specific local GCC rates of change. The proposed model is more than twice as efficient as SLR for estimating superpixel-patient slopes and identifies a higher proportion of deteriorating superpixels than SLR while minimizing false-positive detection rates.

Translational Relevance

The proposed HSL model can be used to model macular structural measurements to detect individual glaucoma progression earlier and more efficiently in clinical and research settings.

Structure-Function Relationship in Keratoconus: Spatial and Depth Vision

Purpose

The purpose of this study was to determine changes in spatial and depth vision with increasing severity of keratoconus and to model the structure-function relationship to identify distinct phases of loss in visual function with disease severity.

Methods

Best-spectacle corrected, monocular high-contrast visual acuity, contrast sensitivity function (CSF) and stereoacuity of 155 cases (16-31 years) with mild to advanced bilateral keratoconus was determined using standard psychophysical tests. Disease severity was quantified using the multimetric D-index. The structure-function relationship was modeled using linear, positive exponential, negative exponential, and logistic nonlinear regression equations.

Results

The logistic regression model explained the highest proportion of variance for spatial vision, without bias in the residual plots (R2 ≥ 66%, P < 0.001). Visual acuity showed a distinct ceiling phase and a steeper loss rate with increasing D-index (1.8 units/D-index) in this model. The area under the CSF lacked this ceiling phase and had a shallower loss rate (0.28 units/D-index). Stereoacuity loss with D-index was poorly explained by all models tested (P ≤ 0.2). Cases with lower and bilaterally symmetric D-index had better stereoacuity (181.6-376 arc seconds) than those with higher D-index (>400 arc second); both were significantly poorer than controls (approximately 30 arc second).

Conclusions

Vision loss in keratoconus varies with the visual function parameter tested. Contrast sensitivity may be an earlier indicator of spatial vision loss than visual acuity. Depth perception is significantly deteriorated from very early stages of the disease.

Translational Relevance

The study outcomes may be used to forecast longitudinal vision loss in keratoconus and to apply appropriate interventions for timely preservation/enhancement of vulnerable visual functions.

Primary Open Angle Glaucoma Diagnosis Using Pattern Electroretinogram Parameters

Background

Glaucoma is the most typical cause of permanent blindness. POAG, or primary open angle glaucoma, is the most common type. The pattern electroretinogram (PERG) has become a promising technique for detecting glaucoma early-on. The goal of this study was to assess the ability of PERG to diagnose POAG, especially in early, difficult-to-diagnose cases in comparison with other already established diagnostic methods.

Methods

150 participants (300 eyes) were enrolled in a cross-sectional study at ophthalmology department at Menoufia University Hospital in August 2022 to February 2023. All recruited participants underwent comprehensive ophthalmological and PERG exams. The studied eyes were divided into three groups as 100 normal eyes (Group I), 100 eyes with preperimetric glaucoma (Group II), and 100 eyes with established perimetric glaucoma (Group III).

Results

OCT-RNFL average thickness had a significant positive correlation with P50 latency (r=0.289, p=0.041) or P50 amplitude (r=0.302, p=0.018) and N95 amplitude (r=0.640, p=0.001) among group (II). Also, RNFL thickness had negative correlation with P50 amplitude (r= -0.268, p=0.043) among group (III). RNFL thickness and P50 and N95 amplitude showed highest AUC values in detecting preperimetric glaucomatous eyes vs normal eyes (AUC=0.927, 0.952, 904), and for detecting established perimetric glaucomatous eyes vs normal eyes (AUC=1.00, 0.957, 0.983 respectively) compared with VF MD which showed AUC (0.458 and 0.901 respectively).

Conclusion

Glaucoma patients exhibit PERG alterations (comparable to RNFL thickness changes) so, it could be used as an accurate diagnostic method in POAG. Because PERG alterations occur before visual field abnormalities, it could be relied on as an early diagnostic tool in preperimetric glaucoma. We can use both RNFL thickness assessment by OCT with PERG parameters as complementary tests for accurate diagnosis of preperimetric glaucoma which represents the most difficult diagnostic challenge in glaucoma diagnosis.

Endpoints for clinical trials in ophthalmology

With the identification of novel targets, the number of interventional clinical trials in ophthalmology has increased. Visual acuity has for a long time been considered the gold standard endpoint for clinical trials, but in the recent years it became evident that other endpoints are required for many indications including geographic atrophy and inherited retinal disease. In glaucoma the currently available drugs were approved based on their IOP lowering capacity. Some recent findings do, however, indicate that at the same level of IOP reduction, not all drugs have the same effect on visual field progression. For neuroprotection trials in glaucoma, novel surrogate endpoints are required, which may either include functional or structural parameters or a combination of both. A number of potential surrogate endpoints for ophthalmology clinical trials have been identified, but their validation is complicated and requires solid scientific evidence. In this article we summarize candidates for clinical endpoints in ophthalmology with a focus on retinal disease and glaucoma. Functional and structural biomarkers, as well as quality of life measures are discussed, and their potential to serve as endpoints in pivotal trials is critically evaluated.

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.

Clinical risk stratification in glaucoma

Glaucoma is the leading cause of preventable sight loss in the United Kingdom and the provision of timely glaucoma care has been highlighted as a significant challenge in recent years. Following a recent high-profile investigation, The Healthcare Safety Investigation Branch recommended the validation of risk stratification models to safeguard the vision-related quality of life of glaucoma patients. There continues to be no nationally agreed evidence-based risk stratification model for glaucoma care across the United Kingdom. Some models have used simple measures of disease staging such as visual field mean deviation as surrogates for risk, but more refined, individualised risk stratification models should include factors related to both visual impairment and visual disability. Candidate tools should also incorporate both ocular and systemic co-morbidities, rate of disease progression, visual needs and driving status and undergo clinical refinement and validation to justify implementation. The disruption to routine glaucoma care caused by the COVID-19 pandemic has only highlighted the importance of such risk stratification models and has accelerated their development, application and evaluation. This review aims to critically appraise the available evidence underpinning current approaches for glaucoma risk stratification and to discuss how these may be applied to contemporary glaucoma care within the United Kingdom. Further research will be essential to justify and validate the utility of glaucoma risk stratification models in everyday clinical practice.

Three-Dimensional Structural Phenotype of the Optic Nerve Head as a Function of Glaucoma Severity

Importance

The 3-dimensional (3-D) structural phenotype of glaucoma as a function of severity was thoroughly described and analyzed, enhancing understanding of its intricate pathology beyond current clinical knowledge.

Objective

To describe the 3-D structural differences in both connective and neural tissues of the optic nerve head (ONH) between different glaucoma stages using traditional and artificial intelligence-driven approaches.

Design, Setting, and Participants

This cross-sectional, clinic-based study recruited 541 Chinese individuals receiving standard clinical care at Singapore National Eye Centre, Singapore, and 112 White participants of a prospective observational study at Vilnius University Hospital Santaros Klinikos, Vilnius, Lithuania. The study was conducted from May 2022 to January 2023. All participants had their ONH imaged using spectral-domain optical coherence tomography and had their visual field assessed by standard automated perimetry.

Main Outcomes and Measures

(1) Clinician-defined 3-D structural parameters of the ONH and (2) 3-D structural landmarks identified by geometric deep learning that differentiated ONHs among 4 groups: no glaucoma, mild glaucoma (mean deviation [MD], ≥-6.00 dB), moderate glaucoma (MD, -6.01 to -12.00 dB), and advanced glaucoma (MD, <-12.00 dB).

Results

Study participants included 213 individuals without glaucoma (mean age, 63.4 years; 95% CI, 62.5-64.3 years; 126 females [59.2%]; 213 Chinese [100%] and 0 White individuals), 204 with mild glaucoma (mean age, 66.9 years; 95% CI, 66.0-67.8 years; 91 females [44.6%]; 178 Chinese [87.3%] and 26 White [12.7%] individuals), 118 with moderate glaucoma (mean age, 68.1 years; 95% CI, 66.8-69.4 years; 49 females [41.5%]; 97 Chinese [82.2%] and 21 White [17.8%] individuals), and 118 with advanced glaucoma (mean age, 68.5 years; 95% CI, 67.1-69.9 years; 43 females [36.4%]; 53 Chinese [44.9%] and 65 White [55.1%] individuals). The majority of ONH structural differences occurred in the early glaucoma stage, followed by a plateau effect in the later stages. Using a deep neural network, 3-D ONH structural differences were found to be present in both neural and connective tissues. Specifically, a mean of 57.4% (95% CI, 54.9%-59.9%, for no to mild glaucoma), 38.7% (95% CI, 36.9%-40.5%, for mild to moderate glaucoma), and 53.1 (95% CI, 50.8%-55.4%, for moderate to advanced glaucoma) of ONH landmarks that showed major structural differences were located in neural tissues with the remaining located in connective tissues.

Conclusions and Relevance

This study uncovered complex 3-D structural differences of the ONH in both neural and connective tissues as a function of glaucoma severity. Future longitudinal studies should seek to establish a connection between specific 3-D ONH structural changes and fast visual field deterioration and aim to improve the early detection of patients with rapid visual field loss in routine clinical care.

Progressive Visual Field Loss and Subsequent Quality of Life Outcomes in Glaucoma

PURPOSE

To evaluate the association between baseline severity of visual field (VF) damage and the initial rates of VF progression with quality of life (QOL) outcomes over an extended follow-up in glaucoma.

DESIGN

Retrospective cohort study.

METHODS

Both eyes of 167 glaucoma or suspected glaucoma patients were followed for 10.0±0.3 years. The National Eye Institute Visual Function Questionnaire (NEI-VFQ)-25 was performed at the end of the follow-up. Separate linear regression models included the VF parameters of the better eye, the worse eye, and the central and peripheral points of the integrated binocular VF to evaluate the association of baseline and initial rates of change of VF parameters (first half of the follow-up) with NEI-VFQ-25 Rasch-calibrated disability scores over an extended follow-up.

RESULTS

All models demonstrated association of worse baseline severity of VF damage with worse subsequent NEI-VFQ-25 scores. Faster rates of decline in VF mean deviation of the better eye and the mean sensitivity of the central and peripheral test locations of the integrated binocular VF were significantly associated with worse subsequent NEI-VFQ-25 scores. VF parameters of the better eye performed better than those of the worse eye (R2 of 0.21, and 0.15, respectively), and the VF parameters of the central test locations performed better than those of the peripheral test locations (R2 of 0.25, and 0.20, respectively).

CONCLUSIONS

Baseline severity and initial rates of change of VF damage are associated with QOL outcomes over an extended follow-up. Assessment of longitudinal VF changes, especially in better eye, provides prognostic utility to identify glaucoma patients at a higher risk for developing disease-related disability.

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.

Comparison of 10-2 and 24-2 Perimetry to Diagnose Glaucoma Using OCT as an Independent Reference Standard

PURPOSE

To compare the performance of the 10-2 test versus 24-2 standard automated perimetry (SAP) test for the diagnosis of glaucoma using OCT as an independent standard for glaucomatous damage.

DESIGN

Cross-sectional study.

PARTICIPANTS

A total of 1375 pairs of 10-2 and 24-2 SAP tests from 569 eyes of 339 subjects were used for the analysis. A total of 440 (77%) eyes had a diagnosis of glaucoma, and 129 (23%) eyes were normal. All participants underwent 10-2 and 24-2 SAP tests within 30 days.

METHODS

Glaucomatous severity was quantified based on OCT macula ganglion cell layer (mGCL) and circumpapillary retinal nerve fiber layer. The area under the receiver operating characteristic (ROC) curve (AUC) was used to compare 10-2 and 24-2 metrics for discriminating healthy eyes from those of glaucoma, at different levels of disease severity.

MAIN OUTCOME MEASURES

Areas under the ROC curves and sensitivities at fixed specificities of 80% and 95%.

RESULTS

The overall AUC for mean deviation (MD) for the 24-2 test (0.808) was significantly higher than that of the 10-2 test (0.742; P < 0.001). When compared at different stages of the disease, the 24-2 test performed generally better than the 10-2 test, notably in the earlier stages of the disease. For early damage (first quartile), the 24-2 MD had an AUC of 0.658 versus 0.590 for 10-2 MD (P = 0.018). For advanced damage (fourth quartile), corresponding values were 0.954 vs. 0.903 (P = 0.013). Similar trends were observed when glaucoma severity was defined based on structural macular damage with mGCL thickness.

CONCLUSIONS

The 24-2 SAP test had better diagnostic accuracy compared with that of the 10-2 test for detecting equivalent levels of glaucomatous damage, as measured by quantitative assessment of retinal nerve fiber layer and macula by OCT.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Survival of Visual Function in Patients with Advanced Glaucoma after Standard Guarded Trabeculectomy with MMC

Surgical intervention in patients with severe glaucoma remains controversial, especially in unilateral cases with a minimally affected fellow eye. Many question the benefit of trabeculectomy in such cases due to high complication rates and prolonged recovery. In this retrospective, non-comparative, interventional case series we aimed to determine the effect of trabeculectomy or combined phaco-trabeculectomy on the visual function of advanced glaucoma patients. Consecutive cases with perimetric mean deviation loss worse than -20 dB were included. Survival of visual function according to five predetermined visual acuity and perimetric criteria was set as the primary outcome. Qualified surgical success utilizing two different sets of criteria commonly used in the literature constituted secondary outcomes. Forty eyes with average baseline visual field mean deviation -26.3 ± 4.1 dB were identified. The average pre-operative intraocular pressure was 26.5 ± 11.4 mmHg and decreased to 11.4 ± 4.0 mmHg (p < 0.001) after an average follow-up of 23.3 ± 15.5 months. Visual function was preserved at two years in 77% or 66% of eyes respectively according to two different sets of visual acuity and perimetric criteria. Qualified surgical success was 89%, 72% at 1 and 3 years respectively. Trabeculectomy and/or phaco-trabeculectomy is associated with meaningful visual outcomes in patients with uncontrolled advanced glaucoma.

Macular integrity assessment microperimeter, Humphrey field analyzer and OCT in glaucoma practice: a correlation study

OBJECTIVE

To compare and correlate retinal sensitivities measured with macular integrity assessment microperimetry (MAIA-MP) and Humphrey field analyzer (HFA) 10-2 tests with structural parameters obtained from optical coherence tomography (OCT) in primary open-angle glaucoma (POAG) and ocular hypertension.

METHODS

This study included 63 participants (22 with POAG, 20 with ocular hypertension, and 21 control individuals). All participants underwent HFA 10-2 and MAIA-MP (macular retinal sensitivity tests) and measurements for optic nerve head (ONH), peripapillary retinal nerve fibre layer thickness (PRNFLT), and ganglion cell inner plexiform layer thickness (GCIPLT) using OCT. The relationship between macular retinal sensitivity and OCT parameters was evaluated by Pearson correlation analysis and linear regression modelling.

RESULTS

POAG cases had a strong association between the MAIA-MP and ONH parameters (optic disc area [ODA], p = 0.037; cup volume, p = 0.043), PRNFLT (average, p = 0.009; inferior PRNFLT, p = 0.004), and GCIPLT in all macula sectors (p ≤ 0.005 for all). HFA 10-2 had a moderate correlation with the ONH parameters (cup-to-disc ratio [CDR], p = 0.042; vertical CDR, p = 0.037; cup volume, p = 0.037; ODA, p = 0.014), PRNFLT (average, inferior, and nasal, p < 0.05 for all), and GCIPLT in all macula sectors (p < 0.005 for all). OHT cases had a weak correlation between HFA 10-2 and nasal and superior PRNFLTs (p = 0.035 and p = 0.047, respectively).

CONCLUSION

MAIA-MP and HFA 10-2 functional parameters have strong correlations with the structural parameters obtained by OCT in POAG cases. Both devices are useful in assessing the central visual field in glaucoma, with MAIA-MP potentially beneficial in patients with limited cooperation or poor vision.

Screening fundus photography predicts and reveals risk factors for glaucoma conversion in eyes with large optic disc cupping

This study aimed to investigate the risk factors for glaucoma conversion and progression in eyes with large optic disc cupping without retinal nerve fiber layer defect (RNFLD). Five hundred forty-two eyes of 271 subjects who had a vertical cup-to-disc ratio (CDR) ≥ 0.6 without RNFLD were enrolled. Characteristics for optic disc configuration (including CDR, vertical cupping, ISNT rule, disc ovality, peripapillary atrophy [PPA]-to-disc area [DA] ratio, and lamina cribrosa pore visibility) and blood vessels (including central retinal vessel trunk [CRVT] nasalization, bayoneting of vessels, baring of circumlinear vessels, history of disc hemorrhage [DH] and vessel narrowing/sclerotic change) were evaluated. From a median follow-up of 11.3 years, 26.6% of eyes (n = 144) developed RNFLD within a median of 5.1 years. Baseline factors, including vertical CDR ≥ 0.7 (hazard ratio [HR] = 2.12), vertical cupping (HR = 1.93), ISNT rule violation (HR = 2.84), disc ovality ≥ 1.2 (HR = 1.61), PPA-to-DA ratio ≥ 0.4 (HR = 1.77), CRVT nasalization ≥ 60% (HR = 1.77), vessel narrowing/sclerotic change (HR = 2.13), DH history (HR = 5.60), and baseline intraocular pressure ≥ 14 mmHg (HR = 1.70) were significantly associated with glaucoma conversion (all Ps < 0.05). An HR-matched scoring system based on initial fundus photography predicted glaucoma conversion with specificity of 90.4%. Careful examination of the optic nerve head and vascular structures can help to predict the risk of glaucoma conversion in eyes with large optic disc cupping.

[Optical coherence tomography and optical coherence tomography angiography for detecting glaucoma progression. Part 2. Clinical and functional correlations, monitoring of advanced glaucoma and limitations of the method]

The purpose of this study is to analyze the literature on the role of optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) in the diagnosis of glaucoma. This review considers the structural and functional correlations observed during the progression of glaucomatous optic neuropathy, as well as the capabilities of the method in late glaucoma, describes the strengths and weaknesses of OCT and OCTA, and pays particular attention to the role of OCT in assessing the effectiveness of treatment. Optical coherence tomography is the main method for determining the progression of glaucoma, which plays a key role in the choice of treatment algorithm. However, the use of OCT in far advanced glaucoma has certain particularities and limitations. OCTA can be helpful in overcoming this problem.

Assessing Usability of Smartwatch Digital Health Devices for Home Blood Pressure Monitoring among Glaucoma Patients

Glaucoma is a leading cause of blindness worldwide. Blood pressure (BP) dysregulation is a known risk factor, and home-based BP monitoring is increasingly used, but the usability of digital health devices to measure BP among glaucoma patients is not well studied. There may be particular usability challenges among this group, given that glaucoma disproportionately affects the elderly and can cause visual impairment. Therefore, the goal of this mixed-methods study was to assess the usability of a smart watch digital health device for home BP monitoring among glaucoma patients. Adult participants were recruited and given a smartwatch blood pressure monitor for at-home use. The eHEALS questionnaire was used to determine baseline digital health literacy. After a week of use, participants assessed the usability of the BP monitor and related mobile app using the Post-study System Usability Questionnaire (PSSUQ) and the System Usability Scale (SUS), standardized instruments to measure usability in health information technology interventions. Variations in scores were evaluated using ANOVA and open-ended responses about participants' experience were analyzed thematically. Overall, usability scores corresponded to the 80th-84th percentile, although older patients endorsed significantly worse usability based on quantitative scores and additionally provided qualitative feedback describing some difficulty using the device. Usability for older patients should be considered in the design of digital health devices for glaucoma given their disproportionate burden of disease and challenges in navigating digital health technologies, although the overall high usability scores for the device demonstrates promise for future clinical applications in glaucoma risk stratification.

Impact of Smoking on Visual Field Progression in a Long-term Clinical Follow-up

PURPOSE

To investigate the effect of smoking on rates of progressive visual field (VF) damage over time in glaucoma.

DESIGN

Retrospective cohort study.

PARTICIPANTS

Five hundred eleven eyes of 354 patients with glaucoma followed up from multicenter glaucoma registries.

METHODS

In this longitudinal study, 354 patients with primary open-angle glaucoma with a minimum of 3 years of follow-up and 5 VF tests were enrolled from the Diagnostic Innovations in Glaucoma Study and the African Descent and Glaucoma Evaluation Study. Univariate and multivariate linear mixed models were used to investigate the effects of smoking on rates of 24-2 VF mean deviation loss. Visual field progression was defined using pointwise linear and significant negative VF mean deviation loss. Logistic regression was used to identify baseline factors and whether different levels of smoking intensity were associated with VF progression. Kaplan-Meier survival analysis and the log-rank test were used to compare the cumulative risk ratio of progression between smoker and never smoker groups.

MAIN OUTCOME MEASURES

Visual field progression.

RESULTS

Five hundred eleven eyes of 354 patients were included over the median follow-up of 12.5 years. Median baseline age was 64.8 years. Of the 354 patients, 124 (35%) were Black, and 149 (42.1%) and 168 (59.8%) had reported a history of smoking or alcohol consumption, respectively. In a multivariate model, higher smoking intensity was associated with faster VF loss (coefficient, -0.05 decibels (dB)/year per 10 pack-years; 95% confidence interval [CI], -0.08 to -0.01 dB/year per 10 pack-years; P = 0.010). Developing VF progression in eyes of heavy smokers (≥ 20 pack-years) was 2.2 times more than in eyes of patients without smoking history (odds ratio, 2.21; 95% CI, 1.02-4.76; P = 0.044). Statistically significant differences were found between heavy smokers (≥ 20 pack-years) and never smokers by Kaplan-Meier analysis (P = 0.011, log-rank test).

CONCLUSIONS

Heavy smokers are more likely to sustain VF loss in eyes with glaucoma. The prospective longitudinal design of this study supports the hypothesis that levels of smoking may be a significant predictor for glaucoma progression. Additionally, this information can be used for clinically relevant tobacco prevention and intervention messages.

Frequency of Optical Coherence Tomography Testing to Detect Progression in Glaucoma

PRCIS

With high specificity and less variability than perimetry, more frequent testing resulted in shorter time to detect progression, though a 6-month testing interval provides a reasonable trade-off for following glaucoma patients using optical coherence tomography (OCT).

PURPOSE

To investigate the time to detect progression in glaucomatous eyes using different OCT test intervals.

MATERIALS AND METHODS

Participants with manifest glaucoma from the African Descent and Glaucoma Evaluation Study (ADAGES), a multicenter, prospective, observational cohort study, were included. A total of 2699 OCT tests from 171 glaucomatous and 149 normal eyes of 182 participants, with at least 5 tests and 2 years of follow-up, were analyzed. Computer simulations (n=10,000 eyes) were performed to estimate time to detect progression of global circumpapillary retinal nerve fiber layer thickness (cpRNFL) measured with OCT tests. Simulations were based on different testing paradigms (every 4, 6, 12, and 24 mo) and different rates of change (µm/year). Time to detect significant progression ( P <0.05) at 80% and 90% power were calculated for each paradigm and rate of cpRNFL change.

RESULTS

As expected, more frequent testing resulted in shorter time to detect progression. Although there was clear disadvantage for testing at intervals of 24 versus 12 months (~22.4% time [25 mo] increase in time to progression detection) and when testing 12 versus 6 months (~22.1% time [20 mo] increase), the improved time to detect progression was less pronounced when comparing 6 versus 4 months (~11.5% time [10 mo] reduction).

CONCLUSION

With high specificity and less variability than perimetry, a 6-month testing interval provides a reasonable trade-off for following glaucoma patients using OCT.

Glaucoma Diagnostic Performance of Retinal Blood Flow Measurement With Doppler Optical Coherence Tomography

Purpose

The purpose of this study was to evaluate the diagnostic performance of retinal blood flow (RBF) measured with the Doppler optical coherence tomography (OCT) segmental scanning method to distinguish between healthy and glaucoma eyes.

Methods

Fifty-eight patients with normal tension glaucoma (NTG) who had a single-hemifield visual field defect and 44 age-matched healthy subjects were enrolled. Retinal nerve fiber layer thickness (RNFLT) was measured with swept-source OCT. Superior and inferior temporal arteries (TAs) and temporal veins (TVs) RBF were measured with Doppler OCT. The area under the curve (AUC) of the receiver operating characteristic (ROC) was used to compare the diagnostic performances in the damaged and normal hemispheres.

Results

Multivariate regression analysis showed TA RBF and TV RBF were significantly reduced in the damaged and normal hemispheres. The ROC analysis showed that the AUC for quadrant RNFLT, TA RBF, and TV RBF were 0.973, 0.909, and 0.872 in the damaged hemisphere, respectively. The AUC values in the normal hemisphere were 0.783, 0.744, and 0.697, respectively. The combination of quadrant RNFLT and TA/TV RBF had a greater AUC than quadrant RNFLT alone in both damaged (AUC = 0.987) and normal (AUC = 0.825) hemispheres.

Conclusions

In NTG eyes with single-hemifield damage, the RBF was found to be significantly reduced in the damaged and normal hemispheres independent from structural changes. The combination of RNFLT and RBF could improve diagnostic performances for glaucoma.

Translational Relevance

Combining morphological and blood flow measurements with Doppler OCT may be useful in glaucoma diagnosis.

Smoking Cessation May Reduce Risk of Visual Field Progression in Heavy Smokers

PRCIS

The earlier a person quits smoking the more likely is the optic nerve be spared from damage.

PURPOSE

To investigate the effect of smoking cessation on visual field (VF) progression in glaucoma.

METHODS

Primary open angle glaucoma patients with a minimum of 3 years follow-up and 5 VFs were included. Linear mixed models were used to investigate the effects of smoking on the rates of 24-2 VF mean deviation loss after adjusting for confounding factors. Cox proportional hazard regression was used to identify whether different levels of smoking intensity were associated with VF progression with respect to different duration of quitting.

RESULTS

Five hundred eleven eyes of 354 patients were included over the mean follow-up of 12.4 years. Mean baseline age (95% confidence interval) was 62.3 (61.2, 63.4) years. One hundred forty nine (42.1%) patients were smokers. In a multivariable model, smoking intensity was associated with faster VF loss (-0.06, 95% confidence interval (-0.10, -0.01) dB/year per 10 pack-years, P =0.01) among smokers. Heavy smokers (≥20 pack-years) who had quit ˂25 years prior had significantly greater odds of VF progression compared with never smokers (odds ratio=2.49 (1.01, 6.08); P =0.046). There was no significant difference in odds of VF progression in heavy smokers who had quit smoking more than 25 years compared with never smokers ( P =0.43). A significantly higher proportion of VF progression was found in heavy smokers who quit < 25 years compared with heavy smokers who quit ≥25 years by Kaplan-Meier analysis ( P =<0.001).

CONCLUSIONS

After ≥25 years of smoking cessation, the risk of VF progression in former heavy smokers becomes similar to never smokers. Long-term smoking cessation may be associated with lower VF progression in glaucoma patients.

Comparison of retinal nerve fiber layer thickness and Bruch's membrane opening minimum rim width thinning rate in open-angle glaucoma

This study aimed to compare the rate of thinning between retinal nerve fiber layer thickness (RNFLT) and Bruch's membrane opening minimum rim width (BMO-MRW) in open-angle glaucoma (OAG) according to glaucoma severity. We retrospectively reviewed subjects with a total of 111 eyes with OAG that had undergone optical coherence tomography more than four times during more than 3 years of follow-up. The subjects were divided into three groups based on the mean deviation (MD) of the baseline visual field test: high MD (MD > - 2 dB), medium MD (- 2 dB ≥ MD > - 6 dB), and low MD (- 6 dB ≥ MD > - 12 dB) groups. A linear mixed model was employed to compare the rate of thinning between RNFLT and BMO-MRW among the three groups. The rate of RNFLT thinning was fastest in the inferotemporal sector in all three groups. The rate of BMO-MRW thinning was fastest in the inferotemporal sector of the high MD group and the superotemporal sector of the other two groups. Among the three groups, the rate of RNFLT thinning was not significantly different in the global sector and all sectors except the nasal sector. The rate of BMO-MRW thinning in the inferotemporal sector showed no significant difference, but that in the superotemporal sector was faster in the medium MD and low MD groups than in the high MD group. The fastest rate of RNFLT thinning was consistently observed in the inferotemporal sector, but BMO-MRW showed a change in the fastest thinning sector from inferotemporal to superotemporal, with increasing severity in early to moderate OAG. The difference in the changes in the two parameters may help understand the pathogenesis of glaucoma and predict its 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.

Comparison of Diagnostic Ability Between Wide-Field Swept-Source Optical Coherence Tomography Imaging Maps and Heidelberg Retina Tomograph 3 Optic Nerve Head Assessment to Discriminate Glaucomatous and Non-glaucomatous Eyes

Background

In this study, we aimed to determine the diagnostic performance of optic nerve head (ONH), macular, and circumpapillary retinal nerve fiber layer (cpRNFL) thickness measurements of wide-field maps (12 × 9 mm) using swept-source optical coherence tomography (SS-OCT) compared to measurements of the ONH and RNFL parameters measured by Heidelberg Retina Tomograph (HRT3).

Methodology

This case-control study included 39 eyes of 39 glaucoma patients and 36 eyes of 36 normal subjects (control group). All participants underwent standard automated perimetry (SAP) as well as structural measurements by SS-OCT (DRI-OCT, Triton; Topcon Inc., Tokyo, Japan) and HRT3 (Heidelberg Engineering, Heidelberg, Germany). The abilities of the continuous parameters to discriminate between glaucoma and control groups were assessed using areas under the receiver operating characteristic curves (AUCs). To assess the glaucoma diagnostic abilities of each of the categorical variables, sensitivity, specificity, positive predictive value, and negative predictive value were tested.

Results

The highest sensitivities were achieved by the DRI-OCT categorical parameters of Superpixel-200 map and cpRNFL (12 sectors) thickness analysis. The best performing HRT3 continuous parameter was rim volume (AUC = 0.829, 95% confidence interval (CI) = 0.735-0.922), and the best continuous parameter for DRI-OCT wide-field was vertical cdr (AUC = 0.883, 95% CI = 0.805-0.951), followed by total cpRNFL thickness (AUC = 0.862, 95% CI = 0.774-0.951). AUCs for disc area, rim area, linear cdr, and RNFL thickness were not significantly different between the two technologies. Using either the most or the least specific criteria, SuperPixel-200 map always showed the highest sensitivity among the categorical parameters of both technologies (82.1% and 89.7%, respectively). The highest sensitivity among HRT3 classification parameters was shown by MRA and GPS classification algorithms.

Conclusions

Both wide-field DRI-OCT maps and HRT3 showed good diagnostic performance in discriminating glaucoma. Although DRI-OCT thickness values and normative diagnostic classification showed the best performance, more studies are required to determine the clinical role of wide-field DRI-OCT scan in glaucoma diagnosis.

Pointwise Visual Field Estimation From Optical Coherence Tomography in Glaucoma Using Deep Learning

Purpose

Standard automated perimetry is the gold standard to monitor visual field (VF) loss in glaucoma management, but it is prone to intrasubject variability. We trained and validated a customized deep learning (DL) regression model with Xception backbone that estimates pointwise and overall VF sensitivity from unsegmented optical coherence tomography (OCT) scans.

Methods

DL regression models have been trained with four imaging modalities (circumpapillary OCT at 3.5 mm, 4.1 mm, and 4.7 mm diameter) and scanning laser ophthalmoscopy en face images to estimate mean deviation (MD) and 52 threshold values. This retrospective study used data from patients who underwent a complete glaucoma examination, including a reliable Humphrey Field Analyzer (HFA) 24-2 SITA Standard (SS) VF exam and a SPECTRALIS OCT.

Results

For MD estimation, weighted prediction averaging of all four individuals yielded a mean absolute error (MAE) of 2.89 dB (2.50-3.30) on 186 test images, reducing the baseline by 54% (MAEdecr%). For 52 VF threshold values' estimation, the weighted ensemble model resulted in an MAE of 4.82 dB (4.45-5.22), representing an MAEdecr% of 38% from baseline when predicting the pointwise mean value. DL managed to explain 75% and 58% of the variance (R2) in MD and pointwise sensitivity estimation, respectively.

Conclusions

Deep learning can estimate global and pointwise VF sensitivities that fall almost entirely within the 90% test-retest confidence intervals of the 24-2 SS test.

Translational Relevance

Fast and consistent VF prediction from unsegmented OCT scans could become a solution for visual function estimation in patients unable to perform reliable VF exams.

Structure-Function Relationship between Cluster Mean Defect and Sector Peripapillary Retinal Nerve Fiber Layer Thickness in Primary Open Angle Glaucoma

Purpose

To determine the structure–function relationship between cluster mean defect (MD) offered by standard automated perimetry and corresponding sector peripapillary retinal nerve fiber layer thickness (pRNFLT) measured with optical coherence tomography (OCT) in primary open angle glaucoma (POAG).

Method

39 healthy eyes (control group), 43 early POAG eyes (global MD ≤ 6 dB, early group), 30 moderate POAG eyes (global MD between 6 and 12 dB, moderate group), and 53 advanced POAG eyes (global MD > 12 dB, advanced group) underwent visual field (VF) examination with Octopus perimeter (dynamic strategy/G2 pattern) and peripapillary retinal nerve fiber layer thickness measurements with RTVue-100 FD-OCT. Spearman analysis was used to investigate the correlation between cluster MDs provided by Octopus perimeter and corresponding sector pRNFLT for the total sample and each subgroup, respectively. Then, linear (y = a+ bx) and curvilinear (quadratic, y = a+bx + cx²) regression analyses were employed to investigate the model for the cluster MD-sector pRNFLT pair with significant correlation. The strength of the relationship was characterized with correlation coefficient (ρ) and coefficient of determination (R²). For the cluster–sector pair that could be fitted by both models, Wilcoxon signed rank test of absolute residuals was used to compare the goodness of fit.

Results

Correlation between cluster MDs and corresponding sector pRNFLT was significant for all clusters in the total sample (ρ values: −0.572 to 0.832, P < 0.001) and in the POAG group (ρ values: −0.551 to −0.777, P < 0.001). The highest ρ values were found for cluster-sector pair 9 and pair 3, respectively. The curvilinear (quadratic) model provided better fit for all 10 cluster-sector pairs in the total sample (R² values: 0.431–0.687, P < 0.001) and in the POAG group (R² values: 0.364–0.594, P < 0.01). The highest R² values were found also for cluster–sector pair 9 and pair 3, respectively. In the control group, no significant correlation was found for any cluster–sector pair (P > 0.01). In the early group, correlation was significant for cluster–sector pairs 3, 8, and 9 (ρ values: −0.449, −0.627, and −0.815, resp., P < 0.01). In the moderate group, correlation was significant for pairs 2, 3, 8, and 9 (ρ values: −0.703, −0.556, −0.680, and −0.637, resp., P < 0.01). In the advanced group, correlation was significant (P < 0.01) for all 10 pairs (ρ values: −0.395 to −0.699, P < 0.001) except for pairs 2, 3, and 8, and the highest ρ value was found for pair 1. For all cluster–sector pairs with significant correlation in the early, moderate, and advanced groups, only linear model could be fitted (P < 0.01), except for pair 9 in the early group and pair 5 in the advanced group.

Conclusions

Cluster MD of the Octopus visual field showed significant moderate-to-strong negative correlation and curvilinear (quadratic) relationship with the corresponding sector pRNFLT for POAG. This type of regional structure–function relationship varied according to the severity of POAG, and at each stage, the significantly correlated cluster–sector pairs mainly showed linear relationship. The results could provide guidance for better utilization of this regional structure–function method in the management of different stages of POAG.

External Validation and Clinical Applicability of Two Optical Coherence Tomography-Based Risk Calculators for Detecting Glaucoma

Purpose

To clinically validate the diagnostic ability of two optical coherence tomography (OCT)-based glaucoma diagnostic calculators (GDCs).

Methods

We conducted a retrospective, consecutive sampling of 76 patients with primary open-angle glaucoma, 107 glaucoma suspects, and 67 controls. Demographics, reliable visual field testing, and macular and optic disc OCT were collected. The reference diagnosis was compared against the probability of having glaucoma obtained from two GDCs derived from multivariate logistic regressions using quantitative and qualitative (GDC1) or only quantitative (GDC2) OCT data. The discrimination (area under the curve [AUC]) and calibration (calibration plots) were compared for both calculators and the best OCT parameters.

Results

GDC2 was able to identify 46.9% more suspects and 14.7% more glaucomatous eyes than GDC1. Both GDCs obtained the highest discriminative ability in glaucomatous eyes (GDC1 AUC = 0.949; GDC2 = 0.943 vs inferior peripapillary retinal nerve fiber layer [pRNFL] = 0.931; P = 0.43). The discriminating ability was not as good for glaucoma suspects, but the GDCs were not inferior to pRNFL (GDC 1 AUC = 0.739; GDC2 = 0.730; inferior pRNFL = 0.760; P = 0.54) and GDC2 was still able to correctly identify up to 30.8% more cases than the conventional OCT classification. Calibration showed risk underestimation for both groups and calculators, but it was better in GDC2 and in patients with glaucoma.

Conclusions

OCT-based calculators showed an excellent diagnostic performance in glaucomatous eyes. GDC2 was able to identify approximately 30% more cases than the conventional pRNFL inferior OCT classification in both groups, suggesting a potential role of these composite scores in clinical practice.

Translational Relevance

These OCT-based calculators may improve glaucoma diagnosis in clinical care.

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.

Association Between Serum Vitamin D Level and Rates of Structural and Functional Glaucomatous Progression

PRCIS

In a retrospective cohort study, serum vitamin D levels were not associated with rates of structural or functional loss in glaucoma patients, suggesting that low vitamin D level is not a risk factor for progression.

PURPOSE

To investigate the association between serum vitamin D level and rates of functional and structural glaucomatous loss over time.

METHODS

This study included 826 eyes of 536 glaucoma or suspect patients with an average follow-up of 4.8±1.9 years. All patients had at least 1 serum vitamin D measurement, and all eyes had at least 2 reliable standard automated perimetry (SAP) tests and 2 spectral-domain optical coherence tomography (SD OCT) tests with a minimum follow-up of 6 months. Multivariable linear mixed-effects models were used to estimate the association of vitamin D level with rates of change in SAP mean deviation (MD) and OCT retinal nerve fiber layer (RNFL) thickness over time while adjusting for potential confounding factors.

RESULTS

Patients had an average of 3.4±1.7 SAP tests, 4.8±1.9 SD OCT tests, and 2.3±1.9 vitamin D measurements. The average serum vitamin D level was 33.9±13.2 ng/mL. Mean rates of MD and RNFL change were -0.03±0.08 dB/y and -0.68±0.64 µm/y, respectively. After controlling for confounding factors, there was no statistically significant association between mean vitamin D level and rates of MD (β=0.038, 95% CI: -0.006, 0.082, P =0.09) or RNFL loss over time (β=-0.018, 95% CI: -0.092, 0.055, P =0.62).

CONCLUSIONS

We did not find a significant association between vitamin D level and rates of visual field or RNFL loss over time in individuals with glaucoma and glaucoma suspect patients.

Associations between steady-state pattern electroretinography and estimated retinal ganglion cell count in glaucoma suspects

Purpose

To estimate retinal ganglion cell (RGC) count in glaucoma suspects (GS) and ascertain its relationships with steady-state pattern electroretinography (ssPERG) parameters.

Methods

In this prospective cross-sectional study, 22 subjects (44 eyes) were recruited at the Manhattan Eye, Ear, and Throat Hospital. Subjects underwent complete eye examinations, optical coherence tomography, standard automated perimetry, and ssPERG testing. Eyes were divided into two groups based upon clinical data: healthy subjects and GS. RGC count was estimated using the combined structure–function index.

Results

Estimated RGC count, average retinal nerve fiber layer thickness (ARNFLT), and average ganglion cell layer and inner plexiform layer thickness (GCIPLT) were reduced in GS eyes (p ≤ 0.001 for all parameters). Pearson correlations revealed that ssPERG magnitude and magnitudeD correlated with ARNFLT (r ≥ 0.53, p < 0.001), GCIPLT (r > 0.38, p < 0.011), and estimated RGC count (r > 0.46, p < 0.002). Six mediation analyses revealed that estimated RGC count mediated the relationships among ssPERG parameters, ARNFLT, and GCIPLT.

Conclusion

Steady-state PERG parameters demonstrated linear correlations with estimated RGC count. The associations among ssPERG parameters and structural measures were mediated by estimated RGC count.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10633-022-09869-9.

Electrical neurostimulation in glaucoma with progressive vision loss

Background

The retrospective study provides real-world evidence for long-term clinical efficacy of electrical optic nerve stimulation (ONS) in glaucoma with progressive vision loss.

Methods

Seventy glaucoma patients (45 to 86 y) with progressive vision loss despite therapeutic reduction of intraocular pressure (IOP) underwent electrical ONS. Closed eyes were separately stimulated by bipolar rectangular pulses with stimulus intensities up to 1.2 mA sufficient to provoke phosphenes. Ten daily stimulation sessions within 2 weeks lasted about 80 min each. Right before ONS at baseline (PRE), vision loss was documented by static threshold perimetry and compared to the same assessment approximately 1 year afterwards (POST). Mean defect (MD) was defined as primary outcome parameter. Perimetries with a reliability factor (RF) of max. 20% were considered.

Results

Perimetry follow-up of 101 eyes in 70 patients fulfilled the criterion of a max. 20% RF. Follow-up was performed on average 362.2 days after ONS. MD significantly decreased from PRE 14.0 dB (median) to POST 13.4 dB (p < 0.01). 64 eyes in 49 patients showed constant or reduced MD as compared to baseline (PRE 13.4 dB vs. POST 11.2 dB). In 37 eyes of 30 patients, MD increased from PRE 14.9 dB to POST 15.6 dB.

Conclusions

Innovative treatments that preserve visual function through mechanisms other than lowering IOP are required for glaucoma with progressive vision loss. The present long-term data document progression halt in more than 63% of affected eyes after ONS and, thus, extend existing evidence from clinical trials.

Macular Blood Flow and Pattern Electroretinogram in Normal Tension Glaucoma

Purpose: To investigate whether macular vessel density (VD) was associated with the pattern electroretinogram (PERG) in normal tension glaucoma (NTG). Design: Cross-sectional study. Methods: Seventy-six eyes from patients with NTG were included in this study. Macular VD was calculated from the superficial retinal layer, including the retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL), using the built-in software provided with the optical coherence tomography angiography (OCTA) device. Functional parameters were obtained from standard automated perimetry (SAP) and PERG, using a commercial ERG stimulator. Moreover, structural parameters, such as peripapillary RNFL and macular ganglion cell/inner plexiform layer (GCIPL) thickness, were measured using OCT. Results: Patients with higher VD had higher N95 amplitude (p = 0.048). Macular VD was significantly correlated with N95 amplitude, irrespective of disease severity (r = 0.352, p = 0.002 for the total subjects and r = 0.276, p = 0.043 for mild glaucoma). According to regression analyses, N95 amplitude and macular VD were bidirectional significant factors (p = 0.035 and 0.019, respectively). For patients with mild to moderate glaucoma, N95 amplitude and macular VD were also significantly associated bidirectionally, according to regression analyses (p = 0.032 and 0.040, respectively). Conclusions: Macular VD was significantly associated with N95 amplitude from PERG. The correlation was prominent in early glaucoma, in contrast to the other structural or functional parameters. When considering that PERG represents the objective function of the retinal ganglion cell (RGC), macular VD was associated with RGC dysfunction before the functional change became apparent on SAP.

Correlation Between Optical Coherence Tomography and Photopic Negative Response of Flash Electroretinography in Ganglion Cell Complex Assessment in Glaucoma Patients

Purpose

To investigate the correlation between the photopic negative response (PhNR) of the light-adapted flash electroretinography (ERG) and measurements of standard automated perimetry (SAP) and optical coherence tomography (OCT) in assessment of retinal ganglion cells’ (RGCs) affection in glaucoma.

Patients and Methods

A cross-sectional study included 40 eyes of glaucoma patients and 40 eyes of age- and gender-matched normal subjects. Participants underwent a complete ophthalmologic assessment, SAP, OCT, and light-adapted flash ERG using the extended PhNR protocol of the International Society for Clinical Electrophysiology of Vision (ISCEV). Glaucomatous eyes were divided into 3 subgroups: mild (n = 15), moderate (n = 11) and severe glaucoma (n = 14) according to the mean deviation (MD) of SAP. Measurements of SAP, OCT and ERG parameters were analyzed, and correlations between PhNR measurements and other study measurements were evaluated.

Results

PhNR amplitudes and PhNR/b-wave ratios were significantly reduced in glaucoma cases compared to healthy controls, and they showed a significant and progressive decline across the three glaucoma subgroups (P < 0.05). An exception to this is PT (b-wave peak to PhNR trough) PhNR amplitude where its reduction was statistically non-significant when comparing between controls and mild glaucoma cases (P = 0.178), and between moderate and severe glaucoma cases (P = 0.714). PhNR amplitudes and PhNR/b-wave ratios correlated significantly with SAP and OCT parameters (P < 0.05).

Conclusion

PhNR correlates well with SAP and OCT parameters in glaucoma assessment. PhNR could be a valuable supplementary tool for objective assessment of the RGCs’ function in glaucoma.

Augmenting Kalman Filter Machine Learning Models with Data from OCT to Predict Future Visual Field Loss: An Analysis Using Data from the African Descent and Glaucoma Evaluation Study and the Diagnostic Innovation in Glaucoma Study

Purpose

To assess whether the predictive accuracy of machine learning algorithms using Kalman filtering for forecasting future values of global indices on perimetry can be enhanced by adding global retinal nerve fiber layer (RNFL) data and whether model performance is influenced by the racial composition of the training and testing sets.

Design

Retrospective, longitudinal cohort study.

Participants

Patients with open-angle glaucoma (OAG) or glaucoma suspects enrolled in the African Descent and Glaucoma Evaluation Study or Diagnostic Innovation in Glaucoma Study.

Methods

We developed a Kalman filter (KF) with tonometry and perimetry data (KF-TP) and another KF with tonometry, perimetry, and global RNFL data (KF-TPO), comparing these models with one another and with 2 linear regression (LR) models for predicting mean deviation (MD) and pattern standard deviation values 36 months into the future for patients with OAG and glaucoma suspects. We also compared KF model performance when trained on individuals of European and African descent and tested on patients of the same versus the other race.

Main Outcome Measures

Predictive accuracy (percentage of MD values forecasted within the 95% repeatability interval) differences among the models.

Results

Among 362 eligible patients, the mean ± standard deviation age at baseline was 71.3 ± 10.4 years; 196 patients (54.1%) were women; 202 patients (55.8%) were of European descent, and 139 (38.4%) were of African descent. Among patients with OAG (n = 296), the predictive accuracy for 36 months in the future was higher for the KF models (73.5% for KF-TP, 71.2% for KF-TPO) than for the LR models (57.5%, 58.0%). Predictive accuracy did not differ significantly between KF-TP and KF-TPO (P = 0.20). If the races of the training and testing set patients were aligned (versus nonaligned), the mean absolute prediction error of future MD improved 0.39 dB for KF-TP and 0.48 dB for KF-TPO.

Conclusions

Adding global RNFL data to existing KFs minimally improved their predictive accuracy. Although KFs attained better predictive accuracy when the races of the training and testing sets were aligned, these improvements were modest. These findings will help to guide implementation of KFs in clinical practice.

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.

Short-term changes in Bruch's membrane opening-based morphometrics during the first week after trabeculectomy

PURPOSE

To evaluate the dynamics of Bruch's membrane opening-based morphometrics of the optic nerve head (ONH) using spectral-domain optical coherence tomography (SD-OCT) during the first week after glaucoma surgery by trabeculectomy with mitomycin C.

METHODS

Prospective, longitudinal analysis of 25 eyes of 25 patients treated by trabeculectomy. Twenty-four eyes had evaluable postoperative SD-OCT examinations. Bruch's membrane opening minimum rim width (BMO-MRW) and peripapillary retinal nerve fiber layer (RNFL) thickness were analyzed at baseline before surgery, 1 day, 2 to 3 days, and 1 week after surgery. Changes compared to baseline were correlated to intraocular pressure (IOP).

RESULTS

One day after surgery, the mean BMO-MRW changed by + 26.17 µm, p = 0.001 (mean IOP reduction by 17.01 mmHg). This increase persisted on day 2-3 with a mean increase of BMO-MRW of + 25.33 µm, p = 0.001 (mean IOP reduction by 20.46 mmHg) and by week 1 with a mean BMO-MRW increase of + 33.17 µm, p < 0.001 (mean IOP reduction by 22.55 mmHg). The increase in BMO-MRW correlated significantly with the reduction of IOP on day 1 (Spearman's rho ρ = 0.656, p = 0.003) and d2-3 (Spearman's rho ρ = 0.479, p = 0.038). There was no statistically significant correlation found between the IOP and the increase in BMO-MRW in week 1. RNFL thickness showed no significant changes at day 1 as well as days 2-3 (p ≥ 0.078, respectively). It showed a small but significant increase in week 1 by 3.94 µm, p = 0.015.

CONCLUSIONS

Structural reversal of disc cupping in BMO-MRW occurs as early as 1 day after trabeculectomy and correlates to the extent of the IOP reduction. During the whole first week after surgery, a strong increase in BMO-MRW can be noted. The changes in BMO-based parameters need to be considered when evaluating patients' longitudinal follow-up.

Structure-function models for estimating retinal ganglion cell count using steady-state pattern electroretinography and optical coherence tomography in glaucoma suspects and preperimetric glaucoma: an electrophysiological pilot study

PURPOSE

To derive and validate structure-function models for estimating retinal ganglion cell (RGC) count using optical coherence tomography (OCT) and steady-state pattern electroretinography (ssPERG) parameters in glaucoma suspects (GS) and preperimetric glaucoma (PPG).

METHODS

In this prospective cross-sectional study, 25 subjects (50 eyes) were recruited at the Manhattan Eye, Ear, and Throat Hospital. Subjects underwent comprehensive eye examinations, OCT, standard automated perimetry (SAP), and ssPERG testing. Eyes were divided into three groups based on the Global Glaucoma Staging System: healthy (N = 30), GS (N = 10), and PPG (N = 10) eyes. The combined structure-function index (CSFI), which estimates retinal ganglion cell count (eRGC_CSFI) from SAP and OCT parameters, was calculated in each study subject. Two prediction formulas were derived using a generalized linear mixed model (GLMM) to predict eRGC_CSFI from ssPERG parameters, age, and average retinal nerve fiber layer thickness (ARNFLT) in 30 eyes selected at random (training group). GLMM predicted values were cross-validated with the remaining 20 eyes (validation group).

RESULTS

The ARNFLT, ssPERG parameters magnitude (Mag) and magnitudeD (MagD), and eRGC_CSFI were significantly different among study groups (ANOVA p ≤ 0.001). Pearson correlations demonstrated significant associations among ARNFLT, ssPERG parameters, and eRGC_CSFI (r² ≥ 0.31, p < 0.001). Two GLMMs predicted eRGC_CSFI from Mag (eRGC_Mag) and MagD (eRGC_MagD), respectively, with significant equations (F(3,18), F(3,19) ≥  58.37, R² = 0.90, p < 0.001). eRGC_Mag and eRGC_MagD in the validation group (R² = 0.89) correlated with eRGC_CSFI similarly to the training group. Multivariate pairwise comparisons revealed that eRGC_Mag and eRGC_MagD distinguished between healthy, GS, and PPG eyes (p ≤ 0.035), whereas independent Mag, MagD, and ARNFLT measures did not distinguish between GS and PPG eyes.

CONCLUSION

This pilot study offers the first combined structure-function models for estimating RGC count using ssPERG parameters. RGC counts estimated with these models were generalizable, strongly associated with CSFI estimates, and performed better than individual ssPERG and OCT measures in distinguishing healthy, GS, and PPG eyes.