Glaucoma research community and FDA look to the future, II: NEI/FDA Glaucoma Clinical Trial Design and Endpoints Symposium: measures of structural change and visual function

Dense optic nerve head deformation estimated using CNN as a structural biomarker of glaucoma progression

PURPOSE

To present a new structural biomarker for detecting glaucoma progression based on structural transformation of the optic nerve head (ONH) region over time.

METHODS

Dense ONH deformation was estimated using deep learning methods namely DDCNet-Multires, FlowNet2, and FlowNetCorrelation, and legacy computational methods namely the topographic change analysis (TCA) and proper orthogonal decomposition (POD) methods. A candidate biomarker was estimated as the average magnitude of deformation of the ONH and evaluated using longitudinal confocal scans of 12 laser treated and 12 contralateral normal eyes of 12 primates from the LSU Experimental Glaucoma Study (LEGS); and 36 progressing eyes and 21 longitudinal normal eyes from the UCSD Diagnostic Innovations in Glaucoma Study (DIGS). Area under the ROC curve (AUC) was used to assess the diagnostic accuracy of the biomarker.

RESULTS

AUROC (95% CI) for LEGS were: 0.83 (0.79, 0.88) for DDCNet-Multires; 0.83 (0.78, 0.88) for FlowNet2; 0.83 (0.78, 0.88) for FlowNet-Correlation; 0.94 (0.91, 0.97) for POD; and 0.86 (0.82, 0.91) for TCA methods. For DIGS: 0.89 (0.80, 0.97) for DDCNet-Multires; 0.82 (0.71, 0.93) for FlowNet2; 0.93 (0.86, 0.99) for FlowNet-Correlation; 0.86 (0.76, 0.96) for POD; and 0.86 (0.77, 0.95) for TCA methods. Lower diagnostic accuracy of the learning-based methods for LEG study eyes were due to image alignment errors in confocal sequences.

CONCLUSION

Deep learning methods trained to estimate generic deformation were able to estimate ONH deformation from image sequences and provided a higher diagnostic accuracy. Our validation of the biomarker using ONH sequences from controlled experimental conditions confirms the diagnostic accuracy of the biomarkers observed in the clinical population. Performance can be further improved by fine-tuning these networks using ONH sequences.

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.

Multiple (frontloaded) visual field tests increase identification of very slow mean deviation progression in glaucoma

OBJECTIVE

To determine the effect of frontloading (multiple) visual field (VF) tests at the same visit for detecting mean deviation (MD) change in slowly progressive glaucoma.

METHODS

This was a computer simulation study. Baseline MD (range, 0 to -12 dB) and progression rate (range, 0 to -0.4 dB/year, non-inclusive) were generated for 10,000 patients. Each patient had 6 simulated "stable" baseline VF tests. Then follow-up VFs (up to 10 years) were generated by incorporating progression rate and within-visit and between-visit variability. The independent variables were number of VF tests per visit (one non-frontloaded or two frontloaded), VF reliability (100%, 85%, or 70%), repeat testing because of unreliable results (yes or no), and follow-up interval (6-monthly or yearly). The outcomes were detection of progression (MD slope that was negative and significant at p < 0.05), MD at detection, and number of years to detection.

RESULTS

Frontloading identified more progressors (62.7%-79.2%) compared with non-frontloading (31.0%-36.7%) at 10 years (p < 0.0001). Six-monthly follow-ups led to greater detection than yearly intervals. Progressors detected by both methods were detected by the non-frontloaded method sooner (up to 0.26 years), but this was small and not clinically significant (MD difference, 0.06 dB). An increase (less severe) in MD, an increase (slower) in progression rate, and an increase in SD of baseline VFs decreased the likelihood of detecting progression.

CONCLUSIONS

Frontloading VF tests at 6-monthly intervals improve detection rates of MD progression in slowly progressive glaucoma patients compared with performing 1 test per visit at yearly intervals.

Remote Contrast Sensitivity Testing Seems to Correlate With the Degree of Glaucomatous Macular Damage

PRCIS

Remote contrast sensitivity (CS) testing through a free downloadable home test correlates with glaucomatous macular damage measured by 10-2 visual field (VF) testing.

PURPOSE

To assess the feasibility and validity of home CS monitoring as a measure of glaucomatous damage using a free downloadable smartphone application.

METHODS

Twenty-six participants were asked to remotely use the Berkeley Contrast Squares (BCS) application, a free downloadable tool that records the user's CS for varying degrees of visual acuity. An instructional video detailing how to download and use the application was sent to the participants. Subjects were asked to send logarithmic CS results with a minimum 8-week test-retest window, and test-retest reliability was measured. Results were validated against office-based CS testing that was collected within the previous 6 months. Validity analysis was also carried out to determine whether CS as measured by BCS is a good predictor of 10-2 and 24-2 VF mean deviation (MD).

RESULTS

There was a high BCS test-retest reliability with an intraclass correlation coefficient score of 0.91 and a significant correlation between repeat test results and baseline test scores (Pearson, 0.86, P < 0.0001). There was significant agreement between unilateral CS scores as measured by BCS and office-based CS testing ( b = 0.94, P < 0.0001, 95% CI: 0.61 to 1.27). Unilateral CS as measured by BCS was significantly associated with 10-2 VF MD ( r2 = 0.27, P = 0.006, 95% CI: 3.7 to 20.6), but not with 24-2 VF MD ( P = 0.151).

CONCLUSION

This study suggests that a free, rapid home CS test correlates with glaucomatous macular damage as measured by 10-2 VF.

A potential primary endpoint for clinical trials in glaucoma neuroprotection

The purpose of this retrospective, longitudinal study is to evaluate the relationship between MD slope from visual field tests collected over a short period of time (2 years) and the current United States' Food and Drug Administration (FDA) recommended endpoints for visual field outcomes. If this correlation is strong and highly predictive, clinical trials employing MD slopes as primary endpoints could be employed in neuroprotection clinical trials with shorter duration and help expedite the development of novel IOP-independent therapies. Visual field tests of patients with or suspected glaucoma were selected from an academic institution and evaluated based on two functional progression endpoints: (A) five or more locations worsening by at least 7 dB, and (B) at least five test locations based upon the GCP algorithm. A total of 271 (57.6%) and 278 (59.1%) eyes reached Endpoints A and B, respectively during the follow up period. The median (IQR) MD slope of eyes reaching vs. not reaching Endpoint A and B were -1.19 (-2.00 to -0.41) vs. 0.36 (0.00 to 1.00) dB/year and -1.16 (-1.98 to -0.40) vs. 0.41 (0.02 to 1.03) dB/year, respectively (P < 0.001). It was found that eyes experiencing rapid 24-2 visual field MD slopes over a 2-year period were on average tenfold more likely to reach one of the FDA accepted endpoints during or soon after that period.

Visual Field Endpoints for Neuroprotective Trials: A Case for AI-Driven Patient Enrichment

PURPOSE

To evaluate whether an artificial intelligence (AI) model can better select candidates that would demonstrate visual field (VF) progression, in order to shorten the duration or the number of patients needed for a clinical trial.

DESIGN

Retrospective cohort study.

METHODS

7428 eyes of 3871 patients from the University of Washington Department of Ophthalmology VF Dataset were included. Progression was defined as at least 5 locations with >7 dB of change compared with baseline on 2 consecutive tests. Progression for all patients, a subgroup of the fastest progressing based on survival curves, and patients selected based on an elastic net Cox regression model were compared. The model was trained on pointwise threshold deviation values of the first VF, age, gender, laterality, and the mean total deviation (MD) at baseline.

RESULTS

A total of 13% of all patients met the criteria for progression at 5 years. Differences in survival were observed when stratified by MD and age (P < .0001). Those at risk of progression included patients aged 60 to 80 years with an initial MD < -5.0. This subgroup decreased the sample size required to detect progression compared with the entire cohort. The AI model-selected patients required the lowest number of patients for all effect sizes and trial lengths. For a trial length of 3 years and effect size of 30%, the number of patients required was 1656 (95% CI, 1638-1674), 903 (95% CI, 884-922), and 636 (95% CI, 625-646) for the entire cohort, the subgroup, and the model-selected patients, respectively.

CONCLUSION

An AI model can identify high-risk patients to substantially reduce the number of patients needed or study duration required to meet clinical trial endpoints.

Comparison of machine learning approaches for structure-function modeling in glaucoma

To evaluate machine learning (ML) approaches for structure-function modeling to estimate visual field (VF) loss in glaucoma, models from different ML approaches were trained on optical coherence tomography thickness measurements to estimate global VF mean deviation (VF MD) and focal VF loss from 24-2 standard automated perimetry. The models were compared using mean absolute errors (MAEs). Baseline MAEs were obtained from the VF values and their means. Data of 832 eyes from 569 participants were included, with 537 Asian eyes for training, and 148 Asian and 111 Caucasian eyes set aside as the respective test sets. All ML models performed significantly better than baseline. Gradient-boosted trees (XGB) achieved the lowest MAE of 3.01 (95% CI: 2.57, 3.48) dB and 3.04 (95% CI: 2.59, 3.99) dB for VF MD estimation in the Asian and Caucasian test sets, although difference between models was not significant. In focal VF estimation, XGB achieved median MAEs of 4.44 [IQR 3.45-5.17] dB and 3.87 [IQR 3.64-4.22] dB across the 24-2 VF for the Asian and Caucasian test sets and was comparable to VF estimates from support vector regression (SVR) models. VF estimates from both XGB and SVR were significantly better than the other models. These results show that XGB and SVR could potentially be used for both global and focal structure-function modeling in glaucoma.

Neuroprotection in neurodegenerations of the brain and eye: Lessons from the past and directions for the future

Background

Neurological and ophthalmological neurodegenerative diseases in large part share underlying biology and pathophysiology. Despite extensive preclinical research on neuroprotection that in many cases bridges and unifies both fields, only a handful of neuroprotective therapies have succeeded clinically in either.

Main body

Understanding the commonalities among brain and neuroretinal neurodegenerations can help develop innovative ways to improve translational success in neuroprotection research and emerging therapies. To do this, analysis of why translational research in neuroprotection fails necessitates addressing roadblocks at basic research and clinical trial levels. These include optimizing translational approaches with respect to biomarkers, therapeutic targets, treatments, animal models, and regulatory pathways.

Conclusion

The common features of neurological and ophthalmological neurodegenerations are useful for outlining a path forward that should increase the likelihood of translational success in neuroprotective therapies.

Prediction of visual field defects from macular optical coherence tomography in glaucoma using cluster analysis

Purpose

To assess the accuracy of cluster analysis‐based models in predicting visual field (VF) defects from macular ganglion cell‐inner plexiform layer (GCIPL) measurements in glaucomatous and healthy cohorts.

Methods

GCIPL measurements were extracted from posterior pole optical coherence tomography (OCT), from locations corresponding to central VF test grids. Models incorporating cluster analysis methods and corrections for age and fovea to optic disc tilt were developed from 493 healthy participants, and 5th and 1st percentile limits of GCIPL thickness were derived. These limits were compared with pointwise 5th and 1st percentile limits by calculating sensitivities and specificities in an additional 40 normal and 37 glaucomatous participants, as well as applying receiver operating characteristic (ROC) curve analyses to assess the accuracy of predicting VF results from co‐localised GCIPL measurements.

Results

Clustered models demonstrated globally low sensitivity, but high specificity in the glaucoma cohort (0.28–0.53 and 0.77–0.91, respectively), and high specificity in the healthy cohort (0.91–0.98). Clustered models showed similar sensitivities and superior specificities compared with pointwise methods (0.41–0.65 and 0.71–0.98, respectively). There were significant differences in accuracy between clusters, with relatively poor accuracy at peripheral macular locations (p < 0.0001 for all comparisons).

Conclusions

Cluster analysis‐based models incorporating age correction and holistic consideration of fovea to optic disc tilt demonstrated superior performance in predicting VF results to pointwise methods in both glaucomatous and healthy eyes. However, relatively low sensitivity and poorer performance at the peripheral macula indicate that OCT in isolation may be insufficient to predict visual function across the macula accurately. With modifications to criteria for abnormality, the concepts suggested by the described normative models may guide prioritisation of VF assessment requirements, with the potential to limit excessive VF testing.

Topical carbonic anhydrase inhibitors and glaucoma in 2021: where do we stand?

Carbonic anhydrase inhibitors (CAIs) have been used for many decades in the treatment of glaucoma. Systemic CAIs were an early treatment option to lower intraocular pressure by reducing aqueous humour production; however, frequent side effects including polyuria and paresthesia contributed to the eventual development of topical CAIs. As topical drug development evolved over time, prostaglandin analogues and beta-blockers have become the gold standard of glaucoma therapies. Although prescribed less often than other classes of topical glaucoma therapies, topical CAIs continue to be used in combination therapies with beta-blockers and alpha agonists. Topical CAIs have also been demonstrated to alter biomarkers of ocular haemodynamics, which have relevance in glaucoma. The purpose of this review is to review and summarise the current state of topical CAI prescribing trends, known efficacy and suggested mechanisms and potential influence on ocular haemodynamics for the future of glaucoma management.

Estimated Utility of the Short-term Assessment of Glaucoma Progression Model in Clinical Practice

IMPORTANCE

Clinical trials of glaucoma therapies focused on protecting the optic nerve have required large sample sizes and lengthy follow-up to detect clinically relevant change due to its slow rate of progression. Whether shorter trials may be possible with more frequent testing and use of rate of change as the end point warrants further investigation.

OBJECTIVE

To describe the design for the Short-term Assessment of Glaucoma Progression (STAGE) model and provide guidance on sample size and power calculations for shorter clinical trials.

DESIGN, SETTING, AND PARTICIPANTS

A cohort study of patients with mild, moderate, or advanced open-angle glaucoma recruited from the Diagnostic Innovations in Glaucoma Study at the University of California, San Diego. Enrollment began in May 2012 with follow-up for every 3 months for 2 years after baseline examination. Follow-up was concluded in September 2016. Data were analyzed from July 2019 to January 2021. Visual fields (VF) and optic coherence tomography (OCT) scans were obtained at baseline and for 2 years with visits every 3 months.

EXPOSURES

Glaucoma was defined as glaucomatous appearing optic discs classified by disc photographs in at least 1 eye and/or repeatable VF damage at baseline.

MAIN OUTCOMES AND MEASURES

Longitudinal rates of change in retinal nerve fiber layer (RNFL) thickness and VF mean deviation (MD) are estimated in study designs of varying length and observation frequency. Power calculations as functions of study length, observation frequency, and sample size were performed.

RESULTS

In a total referred sample of 97 patients with mild, moderate, or advanced glaucoma (mean [SD] age, 69 [11.4] years; 50 [51.5%] were female; 19 [19.6%]), over the 2-year follow-up, the mean VF 24-2 MD slope was -0.32 dB/y (95% CI, -0.43 to -0.21 dB/y) and the mean RNFL thickness slope was -0.54 μm/y (95% CI, -0.75 to -0.32 μm/y). Sufficient power (80%) to detect similar group differences in the rate of change in both outcomes was attained with total follow-up between 18 months and 2 years and fewer than 300 total participants.

CONCLUSIONS AND RELEVANCE

In this cohort study, results from the STAGE model with reduction of the rate of progression as the end point, frequent testing, and a moderate effect size, suggest that clinical trials to test efficacy of glaucoma therapy can be completed within 18 months of follow-up and with fewer than 300 participants.

Neurotrophic Factors in Glaucoma and Innovative Delivery Systems

Glaucoma is a neurodegenerative disease and a worldwide leading cause of irreversible vision loss. In the last decades, high efforts have been made to develop novel treatments effective in inducing protection and/or recovery of neural function in glaucoma, including neurotrophic factors (NTFs). These approaches have shown encouraging data in preclinical setting; however, the challenge of sustained, targeted delivery to the retina and optic nerve still prevents the clinical translation. In this paper, the authors review and discuss the most recent advances for the use of NTFs treatment in glaucoma, including intraocular delivery. Novel strategies in drug and gene delivery technology for NTFs are proving effective in promoting long-term retinal ganglion cells (RGCs) survival and related functional improvements. Results of experimental and clinical studies evaluating the efficacy and safety of biodegradable slow-release NTF-loaded microparticle devices, encapsulated NTF-secreting cells implants, mimetic ligands for NTF receptors, and viral and non-viral NTF gene vehicles are discussed. NTFs are able to prevent and even reverse apoptotic ganglion cell death. Nevertheless, neuroprotection in glaucoma remains an open issue due to the unmet need of sustained delivery to the posterior segment of the eye. The recent advances in intraocular delivery systems pave the way for possible future use of NTFs in clinical practice for the treatment of glaucoma.

Association Between Structure-function Characteristics and Visual Field Outcomes in Glaucoma Subjects With Intraocular Pressure Reduction After Trabeculectomy

PRECIS

Improvements in post-trabeculectomy visual field (VF) outcomes were found to be significantly associated with preoperative nerve fiber layer thickness parameters extracted from the sectorized structure-function relationship, baseline VF, and severity of glaucoma.

OBJECTIVE

To determine whether the preoperative structure-function relationship helps to predict visual outcomes at 1-year post-trabeculectomy.

PATIENTS AND METHODS

In total, 91 eyes from 87 participants who successfully underwent trabeculectomy were included in our study. All eyes received optical coherence tomography imaging and VF assessment using 30-2 standard automated perimetry preoperatively at baseline and postoperatively 1 year after trabeculectomy. The linear mixed-model analysis was used to assess the association of structure and function at baseline, and multivariate analysis to investigate factors associated with postoperative VF outcomes.

RESULTS

Results from multivariate and univariate analysis for VF 1 year after trabeculectomy showed that a positive preoperative retinal nerve fiber layer thickness deviation from the structure-function model was found to be significantly associated with improved postoperative VF outcomes [β=0.06 dB/μm; 95% confidence interval (CI), 0.03-0.09]. Other significant factors included baseline VF MD (β=-0.18; 95% CI, -0.23 to -0.13) and the presence of severe glaucoma (β=-1.69; 95% CI, -2.80 to -0.57). Intraocular pressure was positively associated with improved VF outcomes only in univariate analysis (β=0.06; 95% CI, 0.01-0.11).

CONCLUSIONS AND RELEVANCE

Characteristics derived from the baseline structure-function relationship were found to be strongly associated with postoperative VF outcomes. These findings suggest that the structure-function relationship could potentially have a role in predicting VF progression after trabeculectomy.

Mapping the Contrast Sensitivity of the Visual Field With Bayesian Adaptive qVFM

Current clinical evaluation, which focuses on central vision, could be improved through characterization of residual vision with peripheral testing of visual acuity, contrast sensitivity, color vision, crowding, and reading speed. Assessing visual functions in addition to light sensitivity, a comprehensive visual field map (VFM) would be valuable for detecting and managing eye diseases. In a previous study, we developed a Bayesian adaptive qVFM method that combines a global module for preliminary assessment of the VFM's shape and a local module for assessment at individual retinal locations. The method was validated in measuring the light sensitivity VFM. In this study, we extended the qVFM method to measure contrast sensitivity across the visual field. In both simulations and psychophysics, we sampled 64 visual field locations (48 x 48 deg) and compared the qVFM method with a procedure that tested each retinal location independently (qFC; Lesmes et al., 2015). In each trial, subjects were required to identify a single optotype (size: 2.5 x 2.5 deg), one of 10 filtered Sloan letters. To compare the accuracy and precision of the two methods, three simulated eyes were tested in 1,280 trials with each method. In addition, data were collected from 10 eyes (5 OS, 5 OD) of five normal observers. For simulations, the average RMSE of the estimated contrast sensitivity with the qVFM and qFC methods were 0.057 and 0.100 after 320 trials, and 0.037 and 0.041 after 1,280 trials [all in log10 units, represent as log(sensitivity)], respectively. The average SD of the qVFM and qFC estimates were 0.054 and 0.096 after 320 trials, and 0.032 and 0.041 after 1,280 trials, respectively. The within-run variability (68.2% HWCIs) were comparable to the cross-run variability (SD). In the psychophysics experiment, the average HWCI of the estimated contrast sensitivity from the qVFM and qFC methods across the visual field decreased from 0.33 on the first trial to 0.072 and 0.16 after 160, and to 0.060 and 0.10 after 320 trials. The RMSE between the qVFM and qFC estimates started at 0.26, decreased to 0.12 after 160 and to 0.11 after 320 qVFM trials. The qVFM provides an accurate, precise, and efficient mapping of contrast sensitivity across the entire visual field. The method might find potential clinical applications in monitoring vision loss, evaluating therapeutic interventions, and developing effective rehabilitation for visual diseases.

A CNN-aided method to predict glaucoma progression using DARC (Detection of Apoptosing Retinal Cells)

BACKGROUND

A key objective in glaucoma is to identify those at risk of rapid progression and blindness. Recently, a novel first-in-man method for visualising apoptotic retinal cells called DARC (Detection-of-Apoptosing-Retinal-Cells) was reported. The aim was to develop an automatic CNN-aided method of DARC spot detection to enable prediction of glaucoma progression.

METHODS

Anonymised DARC images were acquired from healthy control (n=40) and glaucoma (n=20) Phase 2 clinical trial subjects (ISRCTN10751859) from which 5 observers manually counted spots. The CNN-aided algorithm was trained and validated using manual counts from control subjects, and then tested on glaucoma eyes.

RESULTS

The algorithm had 97.0% accuracy, 91.1% sensitivity and 97.1% specificity to spot detection when compared to manual grading of 50% controls.  It was next tested on glaucoma patient eyes defined as progressing or stable based on a significant (p<0.05) rate of progression using OCT-retinal nerve fibre layer measurements at 18 months. It demonstrated 85.7% sensitivity, 91.7% specificity with AUC of 0.89, and a significantly (p=0.0044) greater DARC count in those patients who later progressed.

CONCLUSION

This CNN-enabled algorithm provides an automated and objective measure of DARC, promoting its use as an AI-aided biomarker for predicting glaucoma progression and testing new drugs.

A novel Bayesian adaptive method for mapping the visual field

Measuring visual functions such as light and contrast sensitivity, visual acuity, reading speed, and crowding across retinal locations provides visual-field maps (VFMs) that are extremely valuable for detecting and managing eye diseases. Although mapping light sensitivity is a standard glaucoma test, the measurement is often noisy (Keltner et al., 2000). Mapping other visual functions is even more challenging. To improve the precision of light-sensitivity mapping and enable other VFM assessments, we developed a novel hybrid Bayesian adaptive testing framework, the qVFM method. The method combines a global module for preliminary assessment of the VFM's shape and a local module for assessing individual visual-field locations. This study validates the qVFM method in measuring light sensitivity across the visual field. In both simulation and psychophysics studies, we sampled 100 visual-field locations (60° × 60°) and compared the performance of qVFM with the qYN procedure (Lesmes et al., 2015) that measured light sensitivity at each location independently. In the simulations, a simulated observer was tested monocularly for 1,000 runs with 1,200 trials/run, to compare the accuracy and precision of the two methods. In the experiments, data were collected from 12 eyes (six left, six right) of six human subjects. Subjects were cued to report the presence or absence of a target stimulus, with the luminance and location of the target adaptively selected in each trial. Both simulations and a psychological experiment showed that the qVFM method can provide accurate, precise, and efficient mapping of light sensitivity. This method can be extended to map other visual functions, with potential clinical signals for monitoring vision loss, evaluating therapeutic interventions, and developing effective rehabilitation for low vision.

New Technologies for Outcome Measures in Glaucoma: Review by the European Vision Institute Special Interest Focus Group

Glaucoma is the leading cause of irreversible blindness worldwide, with an increasing prevalence. The complexity of the disease has been a major challenge in moving the field forward with regard to both pathophysiological insight and treatment. In this context, discussing possible outcome measures in glaucoma trials is of utmost importance and clinical relevance. A recent meeting of the European Vision Institute (EVI) special interest focus group was held on "New Technologies for Outcome Measures in Retina and Glaucoma," addressing both functional and structural outcomes, as well as translational hot topics in glaucoma and retina research. In conjunction with the published literature, this review summarizes the meeting focusing on glaucoma.

[Unmet research and developmental needs in ophthalmology : A consensus-based road map of the European Vision Institute for 2019-2025]

PURPOSE

To define unmet needs in ophthalmology which can realistically be addressed in the next years (2019-2025) and to describe potential avenues for research to address these challenges.

METHODS

Outcomes of a consensus process within the European Vision Institute (EVI, Brussels) are outlined. Disease areas which are discussed comprise glaucoma, retinal dystrophies, diabetic retinopathy, dry eye disease, corneal diseases, cataract and refractive surgery.

RESULTS

Unmet needs in the mentioned disease areas are discussed and realistically achievable research projects outlined.

CONCLUSION

Considerable progress can be made in the field of ophthalmology and patient-relevant outcomes in the near future.

Unmet Needs in Ophthalmology: A European Vision Institute-Consensus Roadmap 2019-2025

PURPOSE

To define unmet needs in ophthalmology that can realistically be addressed in the next 5 years (2019-2025) and describe potential avenues for research to address these challenges.

METHODS

Outcomes of a consensus process within the European Vision institute (Brussels) are outlined. Disease areas that are discussed comprise glaucoma, retinal dystrophies, diabetic retinopathy, dry eye disease, corneal diseases, cataract and refractive surgery.

RESULTS

Unmet needs in the mentioned disease areas are discussed and realistically achievable research projects outlined.

CONCLUSIONS

Considerable progress can be made in the ophthalmic field and patient-relevant outcomes in the near future.

Test-retest repeatability of the pattern electroretinogram and flicker electroretinogram

PURPOSE

To evaluate the repeatability of the steady-state pattern electroretinogram (PERG) and full-field flicker electroretinogram (Flicker ERG) protocols, delivered by the office-based Neuro Optic Vision Assessment (NOVA)™ testing platform, in healthy subjects.

METHODS

Healthy individuals underwent PERG (16° and 24°) and Flicker ERG [fixed luminance (FL) and multi-luminance (ML)] testing protocols. Test-retest repeatability of protocols was calculated using intra-class correlation coefficients (ICC). Reference values of the parameters of the aforementioned tests were also calculated.

RESULTS

The ICCs for the PERG parameters ranged from 0.793 to 0.911 (p < 0.001). The ICCs for the Flicker ERG parameters ranged from 0.968 to 0.994 (p < 0.001). A linear regression analysis was applied to assess the impact of age on ERG responses. Age had a significant impact on all PERG parameters (16° or 24°). The phase response of the FL Flicker ERG significantly decreased with age (β = - 0.837, p ≤ 0.001). The FL Flicker ERG Magnitude was also impacted with a significant quadratic effect of age (β = - 0.0047, p = 0.0004). Similarly, the Phase Area Under the Curve (Phase AUC) of the ML Flicker ERG significantly declined with age (β = - 0.007, p = 0.009), and the impact on the Magnitude AUC was significant as well, with a negative quadratic age effect.

CONCLUSIONS

The PERG and Flicker ERG protocols, delivered by an office-based testing platform, were shown to have good-to-excellent test-retest repeatability when tests were performed in the same order and in immediate succession.

Reproducibility of Measurements of Retinal Structural Parameters Using Optical Coherence Tomography in Stargardt Disease

Purpose

To assess the reproducibility of retinal measurements from optical coherence tomography (OCT) in ABCA4-related Stargardt disease (STGD1).

Methods

The international multicenter Progression of Atrophy Secondary to Stargardt Disease (ProgStar) Study enrolled 259 STGD1 patients. OCT images were graded by the study reading center (RC). Semiautomatic segmentation with manual adjustments was used to segment the layers of retinal pigmentation epithelium, outer segments, inner segments (ISs), outer nuclear layer (ONL), inner retina, and the total retina (TR). The images were overlaid to the Early Treatment Diabetic Retinopathy Study (ETDRS) grid. For each layer, the thickness and the intact area of the ETDRS central subfield, inner ring, and outer ring were recorded, respectively. A different set of RC graders regraded 30 independent ProgStar images to evaluate measurement reproducibility. Reproducibility was assessed graphically and using statistics including intraclass correlation (ICC) and relative absolute difference (RAD).

Results

Across all layers, measurements of the ETDRS central subfield had low ICC and/or large RAD. The outer-ring region was not fully captured in some images. For inner ring, good reproducibility was observed for intact area in the IS (ICC = 0.99, RAD = 4%), thicknesses of the ONL (ICC = 0.93, RAD = 6%), and TR (ICC = 0.99, RAD = 1%).

Conclusions

STGD1's complex morphology made outer retina segmentation challenging. Measurements of the inner ring, including the intact area of IS (i.e., the ellipsoid zone [EZ]) and ONL and TR thicknesses, had good reproducibility and showed anatomical impairment.

Translational Relevance

ONL and TR thicknesses and the EZ intact area in the ETDRS inner ring hold potential as structural endpoints for STGD1 trials. Structure-function relationships need to be further established.

Combining optical coherence tomography with visual field data to rapidly detect disease progression in glaucoma: a diagnostic accuracy study

BACKGROUND

Progressive optic nerve damage in glaucoma results in vision loss, quantifiable with visual field (VF) testing. VF measurements are, however, highly variable, making identification of worsening vision ('progression') challenging. Glaucomatous optic nerve damage can also be measured with imaging techniques such as optical coherence tomography (OCT).

OBJECTIVE

To compare statistical methods that combine VF and OCT data with VF-only methods to establish whether or not these allow (1) more rapid identification of glaucoma progression and (2) shorter or smaller clinical trials.

DESIGN

Method 'hit rate' (related to sensitivity) was evaluated in subsets of the United Kingdom Glaucoma Treatment Study (UKGTS) and specificity was evaluated in 72 stable glaucoma patients who had 11 VF and OCT tests within 3 months (the RAPID data set). The reference progression detection method was based on Guided Progression Analysis™ (GPA) Software (Carl Zeiss Meditec Inc., Dublin, CA, USA). Index methods were based on previously described approaches [Analysis with Non-Stationary Weibull Error Regression and Spatial enhancement (ANSWERS), Permutation analyses Of Pointwise Linear Regression (PoPLR) and structure-guided ANSWERS (sANSWERS)] or newly developed methods based on Permutation Test (PERM), multivariate hierarchical models with multiple imputation for censored values (MaHMIC) and multivariate generalised estimating equations with multiple imputation for censored values (MaGIC).

SETTING

Ten university and general ophthalmology units (UKGTS) and a single university ophthalmology unit (RAPID).

PARTICIPANTS

UKGTS participants were newly diagnosed glaucoma patients randomised to intraocular pressure-lowering drops or placebo. RAPID participants had glaucomatous VF loss, were on treatment and were clinically stable.

INTERVENTIONS

24-2 VF tests with the Humphrey Field Analyzer and optic nerve imaging with time-domain (TD) Stratus OCT™ (Carl Zeiss Meditec Inc., Dublin, CA, USA).

MAIN OUTCOME MEASURES

Criterion hit rate and specificity, time to progression, future VF prediction error, proportion progressing in UKGTS treatment groups, hazard ratios (HRs) and study sample size.

RESULTS

Criterion specificity was 95% for all tests; the hit rate was 22.2% for GPA, 41.6% for PoPLR, 53.8% for ANSWERS and 61.3% for sANSWERS (all comparisons p ≤ 0.042). Mean survival time (weeks) was 93.6 for GPA, 82.5 for PoPLR, 72.0 for ANSWERS and 69.1 for sANSWERS. The median prediction errors (decibels) when the initial trend was used to predict the final VF were 3.8 (5th to 95th percentile 1.7 to 7.6) for PoPLR, 3.0 (5th to 95th percentile 1.5 to 5.7) for ANSWERS and 2.3 (5th to 95th percentile 1.3 to 4.5) for sANSWERS. HRs were 0.57 [95% confidence interval (CI) 0.34 to 0.90; p = 0.016] for GPA, 0.59 (95% CI 0.42 to 0.83; p = 0.002) for PoPLR, 0.76 (95% CI 0.56 to 1.02; p = 0.065) for ANSWERS and 0.70 (95% CI 0.53 to 0.93; p = 0.012) for sANSWERS. Sample size estimates were not reduced using methods including OCT data. PERM hit rates were between 8.3% and 17.4%. Treatment effects were non-significant in MaHMIC and MaGIC analyses; statistical significance was altered little by incorporating imaging.

LIMITATIONS

TD OCT is less precise than current imaging technology; current OCT technology would likely perform better. The size of the RAPID data set limited the precision of criterion specificity estimates.

CONCLUSIONS

The sANSWERS method combining VF and OCT data had a higher hit rate and identified progression more quickly than the reference and other VF-only methods, and produced more accurate estimates of the progression rate, but did not increase treatment effect statistical significance. Similar studies with current OCT technology need to be undertaken and the statistical methods need refinement.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN96423140.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 22, No. 4. See the NIHR Journals Library website for further project information. Data analysed in the study were from the UKGTS. Funding for the UKGTS was provided through an unrestricted investigator-initiated research grant from Pfizer Inc. (New York, NY, USA), with supplementary funding from the NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK. Imaging equipment loans were made by Heidelberg Engineering, Carl Zeiss Meditec and Optovue (Fremont, CA, USA). Pfizer, Heidelberg Engineering, Carl Zeiss Meditec and Optovue had no input into the design, conduct, analysis or reporting of any of the UKGTS findings or this work. The sponsor for both the UKGTS and RAPID data collection was Moorfields Eye Hospital NHS Foundation Trust. David F Garway-Heath, Tuan-Anh Ho and Haogang Zhu are partly funded by the NIHR Biomedical Research Centre based at Moorfields Eye Hospital and UCL Institute of Ophthalmology. David F Garway-Heath's chair at University College London (UCL) is supported by funding from the International Glaucoma Association.

Effectiveness of a Qualitative Approach Toward Evaluating OCT Imaging for Detecting Glaucomatous Damage

Purpose

The purpose of this study was to determine whether a qualitative approach toward evaluating optical coherence tomography (OCT) imaging improves the ability to detect glaucomatous damage compared to a conventional metric of global circumpapillary retinal nerve fiber layer (cpRNFL) thickness.

Methods

A total of 394 healthy eyes and 272 glaucoma eyes were evaluated. Glaucoma eyes were categorized as perimetric (156 eyes) based on a history of three or more consecutive abnormal 24-2 visual field tests or suspected glaucoma if they did not (116 eyes). Customized one-page reports derived using OCT volume scans of the optic disc and macula from these eyes were qualitatively graded for the probability of optic neuropathy affecting the eye.

Results

The sensitivity of detecting perimetric glaucoma eyes with the global circumpapillary RNFL thickness metric and qualitative evaluation of the OCT imaging results were 86.5% and 95.5% at a specificity of 95%, being significantly higher for the latter (P < 0.001). There were seven eyes with perimetric glaucoma missed by the qualitative evaluation. Based upon examination of all available visual fields, at least four of these seven eyes had visual fields that either improved or had abnormalities that were inconsistent over time or with patterns of glaucomatous damage.

Conclusions

Qualitative evaluation of OCT imaging results allows glaucoma eyes with repeatable visual field abnormalities to be detected with a high level of accuracy, performing better than a conventional summary metric of global cpRNFL thickness.

Translational Relevance

Clinical detection of glaucomatous damage with OCT imaging can be optimized through a qualitative evaluation of its results.

Development of a Visual Field Simulation Model of Longitudinal Point-Wise Sensitivity Changes From a Clinical Glaucoma Cohort

Purpose

To develop a new visual field simulation model that can recreate real-world longitudinal results at a point-wise level from a clinical glaucoma cohort.

Methods

A cohort of 367 glaucoma eyes from 265 participants seen over 10.1 ± 2.5 years were included to obtain estimates of “true” longitudinal visual field point-wise sensitivity and estimates of measurement variability. These two components were then combined to reconstruct visual field results in a manner that accounted for correlated measurement error. To determine how accurately the simulated results reflected the clinical cohort, longitudinal variability estimates of mean deviation (MD) were determined by calculating the SD of the residuals from linear regression models fitted to the MD values over time for each eye in the simulated and clinical cohorts. The new model was compared to a previous model that does not account for spatially correlated errors.

Results

The SD of all the residuals for the clinical and simulated cohorts was 1.1 dB (95% confidence interval [CI]: 1.1–1.2 dB) and 1.1 dB (95% CI: 1.1–1.1 dB), respectively, whereas it was 0.4 dB (95% CI: 0.4–0.4 dB) using the previous simulation model that did not account for correlated errors.

Conclusions

A new simulation model accounting for correlated measurement errors between visual field locations performed better than a previous model in estimating visual field variability in glaucoma.

Translational Relevance

This model can provide a powerful framework to better understand use of visual field testing in clinical practice and trials and to evaluate new methods for detecting progression.

[Structural endpoints for glaucoma studies]

BACKGROUND

Structural endpoints have been discussed as surrogate endpoints for the approval of neuroprotective drugs in glaucoma.

OBJECTIVE

Is the evidence strong enough to establish structural endpoints as surrogate endpoints?

MATERIAL AND METHODS

Review of current understanding between structure and function in glaucoma.

RESULTS

The introduction of optical coherence tomography has revolutionized imaging in glaucoma patients. Clinically either the nerve fiber layer thickness can be measured along a circle centered in the optic nerve head or the ganglion cell layer thickness can be assessed in the macular region, the latter being quantified in combination with other inner retinal layers. On a microscopic level there is a strong correlation between structural and functional loss but this relation can only partially be described with currently available clinical methods. This is particularly true for longitudinal course of the disease in glaucoma patients. Novel imaging techniques that are not yet used clinically may have the potential to increase our understanding between structure and function in glaucoma but further research in this field is required.

CONCLUSION

The current evidence does not allow the establishment of structural endpoints as surrogate endpoints for phase 3 studies in glaucoma. Neuroprotective drugs have to be approved on the basis of visual field data because this is the patient-relevant endpoint. Structural endpoints can, however, play an important role in phase 2 and proof of concept studies.

Consensus on Outcome Measures for Glaucoma Effectiveness Trials: Results From a Delphi and Nominal Group Technique Approaches

PURPOSE

Comparing the relative effectiveness of interventions across glaucoma trials can be problematic due to differences in definitions of outcomes. We sought to identify a key set of clinical outcomes and reach consensus on how best to measure them from the perspective of glaucoma experts.

METHODS

A 2-round electronic Delphi survey was conducted. Round 1 involved 25 items identified from a systematic review. Round 2 was developed based on information gathered in round 1. A 10-point Likert scale was used to quantify importance and consensus of outcomes (7 outcomes) and ways of measuring them (44 measures). Experts were identified through 2 glaucoma societies membership-the UK and Eire Glaucoma Society and the European Glaucoma Society. A Nominal Group Technique (NGT) followed the Delphi process. Results were analyzed using descriptive statistics.

RESULTS

A total of 65 participants completed round 1 out of 320; of whom 56 completed round 2 (86%). Agreement on the importance of outcomes was reached on 48/51 items (94%). Intraocular pressure (IOP), visual field (VF), safety, and anatomic outcomes were classified as highly important. Regarding methods of measurement of IOP, "mean follow-up IOP" using Goldmann applanation tonometry achieved the highest importance, whereas for evaluating VFs "global index mean deviation/defect (MD)" and "rate of VF progression" were the most important. Retinal nerve fiber layer (RNFL) thickness measured by optical coherence tomography (OCT) was identified as highly important. The NGT results reached consensus on "change of IOP (mean of 3 consecutive measurements taken at fixed time of day) from baseline," change of VF-MD values (3 reliable VFs at baseline and follow-up visit) from baseline, and change of RNFL thickness (2 good quality OCT images) from baseline.

CONCLUSIONS

Consensus was reached among glaucoma experts on how best to measure IOP, VF, and anatomic outcomes in glaucoma randomized controlled trials.

Evaluation of Visual Field and Imaging Outcomes for Glaucoma Clinical Trials (An American Ophthalomological Society Thesis)

PURPOSE

To evaluate the ability of various visual field (VF) analysis methods to discriminate treatment groups in glaucoma clinical trials and establish the value of time-domain optical coherence tomography (TD OCT) imaging as an additional outcome.

METHODS

VFs and retinal nerve fibre layer thickness (RNFLT) measurements (acquired by TD OCT) from 373 glaucoma patients in the UK Glaucoma Treatment Study (UKGTS) at up to 11 scheduled visits over a 2 year interval formed the cohort to assess the sensitivity of progression analysis methods. Specificity was assessed in 78 glaucoma patients with up to 11 repeated VF and OCT RNFLT measurements over a 3 month interval. Growth curve models assessed the difference in VF and RNFLT rate of change between treatment groups. Incident progression was identified by 3 VF-based methods: Guided Progression Analysis (GPA), 'ANSWERS' and 'PoPLR', and one based on VFs and RNFLT: 'sANSWERS'. Sensitivity, specificity and discrimination between treatment groups were evaluated.

RESULTS

The rate of VF change was significantly faster in the placebo, compared to active treatment, group (-0.29 vs +0.03 dB/year, P<.001); the rate of RNFLT change was not different (-1.7 vs -1.1 dB/year, P=.14). After 18 months and at 95% specificity, the sensitivity of ANSWERS and PoPLR was similar (35%); sANSWERS achieved a sensitivity of 70%. GPA, ANSWERS and PoPLR discriminated treatment groups with similar statistical significance; sANSWERS did not discriminate treatment groups.

CONCLUSIONS

Although the VF progression-detection method including VF and RNFLT measurements is more sensitive, it does not improve discrimination between treatment arms.

Detection of Functional Change Using Cluster Trend Analysis in Glaucoma

Purpose

Global analyses using mean deviation (MD) assess visual field progression, but can miss localized changes. Pointwise analyses are more sensitive to localized progression, but more variable so require confirmation. This study assessed whether cluster trend analysis, averaging information across subsets of locations, could improve progression detection.

Methods

A total of 133 test-retest eyes were tested 7 to 10 times. Rates of change and P values were calculated for possible re-orderings of these series to generate global analysis ("MD worsening faster than x dB/y with P < y"), pointwise and cluster analyses ("n locations [or clusters] worsening faster than x dB/y with P < y") with specificity exactly 95%. These criteria were applied to 505 eyes tested over a mean of 10.5 years, to find how soon each detected "deterioration," and compared using survival models. This was repeated including two subsequent visual fields to determine whether "deterioration" was confirmed.

Results

The best global criterion detected deterioration in 25% of eyes in 5.0 years (95% confidence interval [CI], 4.7-5.3 years), compared with 4.8 years (95% CI, 4.2-5.1) for the best cluster analysis criterion, and 4.1 years (95% CI, 4.0-4.5) for the best pointwise criterion. However, for pointwise analysis, only 38% of these changes were confirmed, compared with 61% for clusters and 76% for MD. The time until 25% of eyes showed subsequently confirmed deterioration was 6.3 years (95% CI, 6.0-7.2) for global, 6.3 years (95% CI, 6.0-7.0) for pointwise, and 6.0 years (95% CI, 5.3-6.6) for cluster analyses.

Conclusions

Although the specificity is still suboptimal, cluster trend analysis detects subsequently confirmed deterioration sooner than either global or pointwise analyses.

Biomarkers and Surrogate Endpoints: Lessons Learned From Glaucoma

With the recent progress in imaging technologies for assessment of structural damage in glaucoma, a debate has emerged on whether these measurements can be used as valid surrogate endpoints in clinical trials evaluating new therapies for the disease. A discussion of surrogates should be grounded on knowledge acquired from their use in other areas of medicine as well as regulatory requirements. This article reviews the conditions for valid surrogacy in the context of glaucoma clinical trials and critically evaluates the role of biomarkers such as IOP and imaging measurements as potential surrogates for clinically relevant outcomes. Valid surrogate endpoints must be able to predict a clinically relevant endpoint, such as loss of vision or decrease in quality of life. In addition, the effect of a proposed treatment on the surrogate must capture the effect of the treatment on the clinically relevant endpoint. Despite its widespread use in clinical trials, no proper validation of IOP as a surrogate endpoint has yet been conducted for any class of IOP-lowering treatments. Although strong evidence has accumulated about imaging measurements as predictors of relevant functional outcomes in glaucoma, there is still insufficient evidence to support their use as valid surrogate endpoints. However, imaging biomarkers could potentially be used as part of composite endpoints in glaucoma trials, overcoming weaknesses of the use of structural or functional endpoints in isolation. Efforts should be taken to properly design and conduct studies that can provide proper validation of potential biomarkers in glaucoma clinical trials.

Translational Pharmacology in Glaucoma Neuroprotection

Glaucoma is both the most common optic neuropathy worldwide and the most common cause of irreversible blindness in the world. The only proven treatment for glaucomatous optic neuropathy is lowering the intraocular pressure, achieved with a variety of pharmacological, laser, and surgical approaches. Over the past 2 decades there has been much basic and clinical research into achieving treatment of the underlying optic nerve damage with neuroprotective approaches. However, none has resulted in regulatory approval based on successful phase 3 studies. This chapter discusses the reasons for this "lost in translation" aspect of glaucoma neuroprotection, and outlines issues at the laboratory and clinical trial level that need to be addressed for successful development of neuroprotective therapies.

Neuroprotection for glaucoma: Requirements for clinical translation

Within the field of glaucoma research, neuroprotection is defined as slowing the functional loss in glaucoma by a mechanism independent of lowering of intraocular pressure. There is currently a great potential for research surrounding neuroprotection as it relates to glaucoma. Anatomical targets for neuroprotection should focus on upstream rather than downstream factors, and could include any part of the retinal ganglion cell, the glia, especially astrocytes or Muller cells, and vasculature. The great number of anatomical targets is exceeded only by the number of possible biochemical pathways and potential treatments. Successful treatment may be accomplished through the targeting of one or even a combination of multiple pathways. Once a treatment is shown effective in vitro, it should be evaluated in vivo with carefully chosen animal models and studied in sufficient numbers to detect statistically and clinically significant effects. Such a drug should have few systemic side effects and its delivery should be optimized so as to encourage compliance. There are still a multitude of possible screens available to test the efficacy of a neuroprotective drug and a single gold standard is ideal for the accurate assessment and comparison of new drugs. Future studies in neuroprotection should investigate the genetic component of the disease, novel pharmaceutical agents for new or known pathways, modulations of scleral biomechanics, and relation to research of other complex disorders of the central nervous system.

Localized Changes in Retinal Nerve Fiber Layer Thickness as a Predictor of Localized Functional Change in Glaucoma

PURPOSE

To determine how well rates of localized retinal nerve fiber layer thickness (RNFLT) change correlate with rates of sensitivity change at corresponding locations in the visual field in glaucoma.

DESIGN

Retrospective cohort study.

METHODS

Three hundred and sixty-four eyes of 191 participants with suspected or confirmed glaucoma, as judged by experienced clinicians, were tested every 6 months with perimetry and optical coherence tomography (OCT). For each 24-2 visual field location, the corresponding sectoral peripapillary RNFLT was defined using a 30-degree sector, centered on the angle of nerve fiber entry into the optic nerve head. Rates of change of pointwise sensitivity and sectoral RNFLT were calculated over the last 8 visits at which reliable data were obtained. Passing-Bablok regression was used to predict the rate of pointwise sensitivity change from the rate of sectoral RNFLT change, for each location.

RESULTS

Rates of sectoral RNFLT change were significantly predictive of rates of pointwise sensitivity change at all locations in the field. Correlations were modest, averaging 0.15, ranging from 0.03 to 0.25 depending on the location. A 1 μm/y more rapid thinning in corresponding sectors was associated with 0.3 dB/y more rapid loss in the superior visual field but less than 0.1 dB/y more rapid loss at many locations in the inferior visual field.

CONCLUSIONS

Localized RNFL thinning is associated with sensitivity loss at corresponding locations in the visual field, and their rates of change are significantly correlated. Peripapillary RNFLT may be used to monitor localized changes caused by glaucoma that have measurable consequences for a patient's vision.

Primary open-angle glaucoma

Glaucoma is an optic neuropathy that is characterized by the progressive degeneration of the optic nerve, leading to visual impairment. Glaucoma is the main cause of irreversible blindness worldwide, but typically remains asymptomatic until very severe. Open-angle glaucoma comprises the majority of cases in the United States and western Europe, of which, primary open-angle glaucoma (POAG) is the most common type. By contrast, in China and other Asian countries, angle-closure glaucoma is highly prevalent. These two types of glaucoma are characterized based on the anatomic configuration of the aqueous humour outflow pathway. The pathophysiology of POAG is not well understood, but it is an optic neuropathy that is thought to be associated with intraocular pressure (IOP)-related damage to the optic nerve head and resultant loss of retinal ganglion cells (RGCs). POAG is generally diagnosed during routine eye examination, which includes fundoscopic evaluation and visual field assessment (using perimetry). An increase in IOP, measured by tonometry, is not essential for diagnosis. Management of POAG includes topical drug therapies and surgery to reduce IOP, although new therapies targeting neuroprotection of RGCs and axonal regeneration are under development.

Neuroretinal Rim Area Change in Glaucoma Patients With Visual Field Progression Endpoints and Intraocular Pressure Reduction. The Canadian Glaucoma Study: 4

PURPOSE

To compare rim area rates in patients with and without the visual field (VF) progression endpoint in the Canadian Glaucoma Study and determine whether intraocular pressure (IOP) reduction following the endpoint altered rim area rate.

DESIGN

Prospective multicenter cohort study.

METHODS

setting: University hospitals.

PATIENT POPULATION

Two hundred and six patients with open-angle glaucoma were examined at 4-month intervals with standard automated perimetry and confocal scanning laser tomography.

INTERVENTION

After the endpoint, IOP was reduced by ≥20%.

OUTCOME MEASURES

Univariate analysis for change in rim area rate and multivariable analysis to adjust for independent covariates (eg, age, sex, and IOP).

RESULTS

Patients with an endpoint (n = 59) had a worse rim area rate prior to the endpoint compared to those without (n = 147; median [interquartile range]: -14 [-32, 11] × 10(-3) mm(2)/y and -5 [-14, 5] × 10(-3) mm(2)/y, respectively, P = .02). In univariate analysis, there was no difference in rim area rate before and after the endpoint (median difference [95% CI], 8 (-10, 24) × 10(-3) mm(2)/y), but the muItivariate analysis showed that IOP reduction >2 mm Hg after the endpoint was strongly linked to a reduction in rim area rate decline (8 × 10(-3) mm(2)/y for each additional 1 mm Hg reduction).

CONCLUSIONS

Patients with a VF endpoint had a median rim area rate that was nearly 3 times worse than those without an endpoint. Lower mean follow-up IOP was independently associated with a slower decline in rim area.

Differences of Intrasession Reproducibility of Circumpapillary Total Retinal Thickness and Circumpapillary Retinal Nerve Fiber Layer Thickness Measurements Made with the RS-3000 Optical Coherence Tomograph

PURPOSE

To evaluate the intrasession reproducibility of various thickness parameters used to diagnose and follow-up glaucoma, in particular circumpapillary total retinal thickness (cpTR) provided by the RS-3000 optical coherence tomograph (OCT).

METHODS

Fifty-three healthy eyes of 28 subjects underwent three consecutive imaging with the RS-3000 Advance OCT (NIDEK, Aichi,Japan) to evaluate the intrasession reproducibility of circumpapillary total retinal thickness (cpTR), circumpapillary retinal nerve fiber layer thickness (cpRNFL), macular ganglion cell complex thickness (mGCC) and macular total retina thickness (mTR) measurements. Intraclass correlation (ICC), coefficient of variation (CV) and reproducibility coefficient (RC) were calculated for each parameter.

RESULTS

The ICC and CV values for mean cpTR and cpRNFL were 0.987 and 0.897, and 0.60% and 2.81%, respectively. The RC values for the mean cpTR and cpRNFL were 5.95 μm and 9.04 μm, respectively. For all cpTR parameters the ICC values were higher and both the CV and RC values were lower than those for the corresponding cpRNFL parameters. The ICC and CV values for superior mGCC, inferior mGCC, superior mTR and inferior mTR were 0.983, 0.980, 0.983 and 0.988, and 0.84%, 0.98%, 0.48% and 0.43%, respectively. The RC values for superior mGCC, inferior mGCC, superior mTR and inferior mTR were 2.86 μm, 3.12 μm, 4.41 μm and 4.43 μm, respectively.

CONCLUSIONS

Intrasession reproducibility of cpTR, mGCC and mTR measurements made on healthy eyes was high. Repeatability of cpTR measurements was better than that of the corresponding cpRNFL measurements. These results suggest that future clinical investigations addressing detection of glaucoma and glaucomatous progression with the RS-3000 OCT may benefit from focusing on the cpTR parameters.

Comparative Effectiveness of First-Line Medications for Primary Open-Angle Glaucoma: A Systematic Review and Network Meta-analysis

TOPIC

Primary open-angle glaucoma (POAG) is a highly prevalent condition worldwide and the most common cause of irreversible sight loss. The objective is to assess the comparative effectiveness of first-line medical treatments in patients with POAG or ocular hypertension through a systematic review and network meta-analysis, and to provide relative rankings of these treatments.

CLINICAL RELEVANCE

Treatment for POAG currently relies completely on lowering the intraocular pressure (IOP). Although topical drops, lasers, and surgeries can be considered in the initial treatment of glaucoma, most patients elect to start treatment with eye drops.

METHODS

We included randomized controlled trials (RCTs) that compared a single active topical medication with no treatment/placebo or another single topical medication. We searched CENTRAL, MEDLINE, EMBASE, and the Food and Drug Administration's website. Two individuals independently assessed trial eligibility, abstracted data, and assessed the risk of bias. We performed Bayesian network meta-analyses.

RESULTS

We included 114 RCTs with data from 20 275 participants. The overall risk of bias of the included trials is mixed. The mean reductions (95% credible intervals) in IOP in millimeters of mercury at 3 months ordered from the most to least effective drugs were as follows: bimatoprost 5.61 (4.94; 6.29), latanoprost 4.85 (4.24; 5.46), travoprost 4.83 (4.12; 5.54), levobunolol 4.51 (3.85; 5.24), tafluprost 4.37 (2.94; 5.83), timolol 3.70 (3.16; 4.24), brimonidine 3.59 (2.89; 4.29), carteolol 3.44 (2.42; 4.46), levobetaxolol 2.56 (1.52; 3.62), apraclonidine 2.52 (0.94; 4.11), dorzolamide 2.49 (1.85; 3.13), brinzolamide 2.42 (1.62; 3.23), betaxolol 2.24 (1.59; 2.88), and unoprostone 1.91 (1.15; 2.67).

CONCLUSIONS

All active first-line drugs are effective compared with placebo in reducing IOP at 3 months. Bimatoprost, latanoprost, and travoprost are among the most efficacious drugs, although the within-class differences were small and may not be clinically meaningful. All factors, including adverse effects, patient preferences, and cost, should be considered in selecting a drug for a given patient.

Exciting directions in glaucoma

Glaucoma is a complex, life-long disease that requires an individualized, multifaceted approach to treatment. Most patients will be started on topical ocular hypotensive eyedrop therapy, and over time multiple classes of drugs will be needed to control their intraocular pressure. The search for drugs with novel mechanisms of action, to treat those who do not achieve adequate intraocular pressure control with, or become refractory to, current therapeutics, is ongoing, as is the search for more efficient, targeted drug delivery methods. Gene-transfer and stem-cell applications for glaucoma therapeutics are moving forward. Advances in imaging technologies improve our understanding of glaucoma pathophysiology and enable more refined patient evaluation and monitoring, improving patient outcomes.

Detecting optic nerve head deformation and retinal nerve fiber layer thinning in glaucoma progression

The application of digital imaging technologies including confocal scanning laser ophthalmoscopy (CSLO), optical coherence tomography (OCT), and scanning laser polarimetry (SLP) has significantly improved the detection of optic nerve head (ONH) deformation and progressive retinal nerve fiber layer (RNFL) thinning for assessment of glaucoma progression. Algorithms for change analysis such as topographic change analysis and guided progression analysis perform event analysis of serial ONH surface height topology maps and RNFL thickness/RNFL retardance maps, respectively, providing a topographical display of the location of significant change. With spectral-domain OCT, it is feasible to delineate and measure the lamina cribrosa surface depth in addition to ONH surface depth and RNFL thickness. Growing evidence from experimental and clinical studies indicates that ONH and lamina cribrosa deformation can be observed prior to detectable RNFL thinning and functional loss in glaucoma. These findings lend support to the notion that upon detection of ONH/lamina cribrosa deformation, a time window for therapeutic intervention for better outcomes may exist. The ONH and the lamina cribrosa are therefore important targets for monitoring glaucoma progression. This review summarizes the latest findings comparing the performance of OCT, CSLO, and SLP for detection of progressive ONH and RNFL damages in glaucoma patients and the clinical implication and limitations of studying the morphological alteration of the ONH, lamina cribrosa, and RNFL in the assessment of glaucoma progression.

Can Visual Field Progression be Predicted by Confocal Scanning Laser Ophthalmoscopic Imaging of the Optic Nerve Head in Glaucoma? (An American Ophthalmological Society Thesis)

PURPOSE

To determine whether confocal scanning laser ophthalmoscopic imaging (Heidelberg retinal tomography [HRT]) can predict visual field change in glaucoma.

METHODS

The study included 561 patients with glaucoma or ocular hypertension whose clinical course was followed at the Mount Sinai Faculty practice. Humphrey visual fields (HVFs) and HRT images were collected on one randomly selected eye per patient. Glaucoma progression was determined by the presence of two sequential statistically significant negative slopes in mean deviation (MD) or visual field index (VFI) at any point during the study period. Trend-based analysis on HRT parameters was used to determine progressive changes and whether these occurred before or after HVF change. Sensitivity and specificity of HRT to predict HVF change were calculated. HVF rate of change was correlated to the rate of change detected by HRT imaging.

RESULTS

Approximately 17% of patients progressed by either MD or VFI criteria. MD and VFI correlated highly and identified overlapping sets of patients as progressing. HRT global parameters had poor sensitivity (∼42%) and moderate specificity (∼67%) to predict HVF progression. Regional stereometric parameters were more sensitive (69%-78%) but significantly less specific (24%-27%). Sensitivity of global stereometric parameters in detecting HVF change was not significantly affected by the level of visual field damage (P=.3, Fisher exact test). HVF rate of change did not correlate with rate of change of HRT parameters.

CONCLUSIONS

Trend-based analysis of HRT parameters has poor sensitivity and specificity in predicting HVF change. This may be related specifically to HRT imaging or may reflect the fact that in some patients with glaucoma, functional changes precede structural alterations.

The pathophysiology and treatment of glaucoma: a review

IMPORTANCE

Glaucoma is a worldwide leading cause of irreversible vision loss. Because it may be asymptomatic until a relatively late stage, diagnosis is frequently delayed. A general understanding of the disease pathophysiology, diagnosis, and treatment may assist primary care physicians in referring high-risk patients for comprehensive ophthalmologic examination and in more actively participating in the care of patients affected by this condition.

OBJECTIVE

To describe current evidence regarding the pathophysiology and treatment of open-angle glaucoma and angle-closure glaucoma.

EVIDENCE REVIEW

A literature search was conducted using MEDLINE, the Cochrane Library, and manuscript references for studies published in English between January 2000 and September 2013 on the topics open-angle glaucoma and angle-closure glaucoma. From the 4334 abstracts screened, 210 articles were selected that contained information on pathophysiology and treatment with relevance to primary care physicians.

FINDINGS

The glaucomas are a group of progressive optic neuropathies characterized by degeneration of retinal ganglion cells and resulting changes in the optic nerve head. Loss of ganglion cells is related to the level of intraocular pressure, but other factors may also play a role. Reduction of intraocular pressure is the only proven method to treat the disease. Although treatment is usually initiated with ocular hypotensive drops, laser trabeculoplasty and surgery may also be used to slow disease progression.

CONCLUSIONS AND RELEVANCE

Primary care physicians can play an important role in the diagnosis of glaucoma by referring patients with positive family history or with suspicious optic nerve head findings for complete ophthalmologic examination. They can improve treatment outcomes by reinforcing the importance of medication adherence and persistence and by recognizing adverse reactions from glaucoma medications and surgeries.

A method to estimate the amount of neuroretinal rim tissue in glaucoma: comparison with current methods for measuring rim area

PURPOSE

To test whether the minimum rim area assessed by spectral domain optical coherence tomography (SD-OCT), based on the shortest distance from the Bruch membrane opening (BMO) to the inner limiting membrane, corresponds more closely to retinal nerve fiber layer (RNFL) thickness and visual field mean deviation (MD) than current rim measures in early glaucoma.

DESIGN

Prospective cross-sectional study.

METHODS

We studied 221 participants with non-endstage glaucoma or high-risk ocular hypertension and performed standard automated perimetry. We received SD-OCT and confocal scanning laser ophthalmoscopy (CSLO) scans on the same day. Rim area measured by CSLO was compared with 3 SD-OCT rim measures from radial B-scans: horizontal rim area between BMO and inner limiting membrane within the BMO plane; mean minimum rim width (BMO-MRW); and minimum rim area (BMO-MRA) optimized within sectors and then summed. Correlations between these measures and either MD from perimetry or RNFL thickness from SD-OCT were compared using the Steiger test.

RESULTS

RNFL thickness was better correlated with BMO-MRA (r = 0.676) or BMO-MRW (r = 0.680) than with either CSLO rim area (r = 0.330, P < 0.001) or horizontal rim area (r = 0.482, P < 0.001). MD was better correlated with BMO-MRA (r = 0.534) or BMO-MRW (r = 0.546) than with either CSLO rim area (r = 0.321, P < 0.001) or horizontal rim area (0.403, P < 0.001). The correlation between MD and RNFL thickness was r = 0.646.

CONCLUSIONS

Minimum rim measurements from SD-OCT are significantly better correlated to both RNFL thickness and MD than rim measurements within the BMO plane or based on the clinical disc margin. They provide new structural parameters for both diagnostic and research purposes in glaucoma.

The value of clinical electrophysiology in the assessment of the eye and visual system in the era of advanced imaging

Electrophysiological techniques allow clinical investigations to include a 'dissection' of the visual system. Using suitable electrophysiological techniques, the 'dissection' allows function to be ascribed to the different photoreceptors (rod and cone photoreceptors), retinal layers, retinal location or the visual pathway up to the visual cortex. Combined with advances in genetics, retinal biochemistry, visual fields and ocular imaging, it is now possible to obtain a better understanding of diseases affecting the retina and visual pathways. This paper reviews core electrophysiological principles that can complement other examination techniques, including advanced ocular imaging, and help the interpretation of other clinical data and thus, refine and guide clinical diagnosis.

Pulsatile motion of the trabecular meshwork in healthy human subjects quantified by phase-sensitive optical coherence tomography

Aqueous leaves the anterior chamber of eye by passing through the trabecular meshwork (TM), a tissue thought to be responsible for increased outflow resistance in glaucoma. Motion assessment could permit characterization of TM biomechanical properties necessary to maintain intra-ocular pressure (IOP) within a narrow homeostatic range. In this paper, we report the first in vivo identification of TM motion in humans. We use a phase-sensitive optical coherence tomography (PhS-OCT) system with sub-nanometer sensitivity to detect and image dynamic pulse-induced TM motion. To permit quantification of TM motion and relationships we develop and apply a phase compensation algorithm permitting removal of the otherwise evitable confounding effects of bulk motion. Twenty healthy human eyes from 10 subjects are imaged. The results permit visualization of pulsatile TM motion visualization by PhS-OCT; correlation with the digital/cardiac pulse is highly significant. The correlation permits assessment of the phase lag and time delay between TM motion and the cardiac pulse. In this study, we find that the digital pulse leads the pulsatile TM motion by a mean phase of 3.53 ± 0.48 rad and a mean time of 0.5 ± 0.14 s in the fundamental frequency. A significant linear relationship is present between the TM phase lag and the heart rate (p value < 0.05). The TM phase lag is also affected by age, the relationship not quite reaching significance in the current study. PhS-OCT reveals pulse-induced motion of the TM that may provide insights into the biomechanics of the tissues involved in the regulation of IOP.

Critical assessment of implantable drug delivery devices in glaucoma management

Glaucoma is a group of heterogeneous disorders involving progressive optic neuropathy that can culminate into visual impairment and irreversible blindness. Effective therapeutic interventions must address underlying vulnerability of retinal ganglion cells (RGCs) to degeneration in conjunction with correcting other associated risk factors (such as elevated intraocular pressure). However, realization of therapeutic outcomes is heavily dependent on suitable delivery system that can overcome myriads of anatomical and physiological barriers to intraocular drug delivery. Development of clinically viable sustained release systems in glaucoma is a widely recognized unmet need. In this regard, implantable delivery systems may relieve the burden of chronic drug administration while potentially ensuring high intraocular drug bioavailability. Presently there are no FDA-approved implantable drug delivery devices for glaucoma even though there are several ongoing clinical studies. The paper critically assessed the prospects of polymeric implantable delivery systems in glaucoma while identifying factors that can dictate (a) patient tolerability and acceptance, (b) drug stability and drug release profiles, (c) therapeutic efficacy, and (d) toxicity and biocompatibility. The information gathered could be useful in future research and development efforts on implantable delivery systems in glaucoma.

Status and perspectives of neuroprotective therapies in glaucoma: the European Glaucoma Society White Paper

Glaucoma, a chronic progressive neuropathy and the most frequent cause of irreversible blindness worldwide, is commonly treated by medication or surgery aimed at lowering intraocular pressure. In view of the limited therapeutic options, the European Glaucoma Society (EGS) sponsored two Think Tank Meetings with the goal of assessing the current status and the overall perspectives for neuroprotective treatment strategies in glaucoma. The results of the meetings are summarized in this EGS White Paper.