Recent developments in visual field testing for glaucoma

The AI revolution in glaucoma: Bridging challenges with opportunities

Recent advancements in artificial intelligence (AI) herald transformative potentials for reshaping glaucoma clinical management, improving screening efficacy, sharpening diagnosis precision, and refining the detection of disease progression. However, incorporating AI into healthcare usages faces significant hurdles in terms of developing algorithms and putting them into practice. When creating algorithms, issues arise due to the intensive effort required to label data, inconsistent diagnostic standards, and a lack of thorough testing, which often limits the algorithms' widespread applicability. Additionally, the "black box" nature of AI algorithms may cause doctors to be wary or skeptical. When it comes to using these tools, challenges include dealing with lower-quality images in real situations and the systems' limited ability to work well with diverse ethnic groups and different diagnostic equipment. Looking ahead, new developments aim to protect data privacy through federated learning paradigms, improving algorithm generalizability by diversifying input data modalities, and augmenting datasets with synthetic imagery. The integration of smartphones appears promising for using AI algorithms in both clinical and non-clinical settings. Furthermore, bringing in large language models (LLMs) to act as interactive tool in medicine may signify a significant change in how healthcare will be delivered in the future. By navigating through these challenges and leveraging on these as opportunities, the field of glaucoma AI will not only have improved algorithmic accuracy and optimized data integration but also a paradigmatic shift towards enhanced clinical acceptance and a transformative improvement in glaucoma care.

The TsiogkaSpaeth grid for detection of neurological visual field defects: a validation study

BACKGROUND

The TsiogkaSpaeth (TS) grid is a new, low-cost, and easy to access portable test for visual field (VF) screening which could be used by clinicians in everyday clinical practice. Our study aimed to determine the validity of an innovative screening grid test for identifying neurological disease-associated VF defects.

METHODS

We enrolled two groups of participants: We assessed the one eye of ten consecutive adult patients with different types of neurological disease associated VF defects and ten eyes of controls in each group. The TS grid test was performed in each group. Sensitivity, specificity, and positive and negative predictive values of the TS grid scotoma area were assessed using the 24-2 VF Humphrey field analyzer (HFA) as the reference standard.

RESULTS

Sensitivity and specificity of the TS grid test were 100% and 90.91%, respectively. The area under curve was 0.9545 with 95% CI 0.87-1.00. There was a significant correlation between the number of missed locations on the TS grid test and the visual field index of the HFA 24-2 (r = 0.9436, P < .0001).

CONCLUSION

The sensitivity and specificity of the TS grid test were high in detecting VF defects in neurological disease. The TS grid test appears to be a reliable, low-cost, and easily accessed alternative to traditional VF tests in diagnosing typical neurological patterns of visual field defects. It would be useful in screening subjects for neurologically derived ocular morbidity in everyday clinical practice and in remote areas deprived of specialized health care services.

Validation of Diagnostic Codes to Identify Glaucoma in Taiwan's Claims Data: A Multi-Institutional Study

Background

Healthcare databases play a crucial role in improving our understanding of glaucoma epidemiology, which is the leading cause of irreversible blindness globally. However, the accuracy of diagnostic codes used in these databases to detect glaucoma is still uncertain.

Aim

To assess the accuracy of ICD-9-CM and ICD-10-CM codes in identifying patients with glaucoma, including two distinct subtypes, primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG).

Methods

We analyzed electronic medical records data from a 2% random sample of patients who newly underwent visual field examination in Taiwan's largest multi-institutional healthcare system from 2011 to 2020. The diagnosis of glaucoma was confirmed by two ophthalmologists, based on the glaucoma diagnostic criteria. The positive predictive value (PPV), negative predictive value (NPV), sensitivity and specificity for ICD-9-CM codes 365.1X and 365.2X, and ICD-10-CM codes H4010X, H4011X, H4012X, H4020X, H4021X, H4022X, H4023X and H4024X for glaucoma were calculated.

Results

We randomly selected 821 patients (mean age: 56.9 years old; female: 50.5%) from the original cohort of 41,050 newly receiving visual field examination in the study. Among 464 cases with an ICD-9-CM glaucoma code, the sensitivity, specificity, PPV and NPV for glaucoma were 86.5, 96.5, 91.9, and 90.9%, respectively. Among 357 cases with an ICD-10-CM glaucoma code, the sensitivity, specificity, PPV and NPV for glaucoma were 87.0, 92.8, 92.2 and 87.9%, respectively. The accuracy of diagnostic codes to identify POAG and PACG remained consistent.

Conclusion

The diagnostic codes were highly reliable for identifying cases of glaucoma in Taiwan's routine healthcare practice. These results provide confidence when using ICD-9-CM and ICD-10-CM codes to define glaucoma cases in healthcare database research in Taiwan.

Comparison of the TEMPO binocular perimeter and Humphrey field analyzer

This study compared between TEMPO, a new binocular perimeter, with the Humphrey Field Analyzer (HFA). Patients were tested with both TEMPO 24-2 Ambient Interactive Zippy Estimated by Sequential Testing (AIZE)-Rapid and HFA 24-2 Swedish Interactive Threshold Algorithm (SITA)-Fast in a randomized sequence on the same day. Using a mixed-effects model, visual field (VF) parameters and reliability indices were compared. Retinal nerve fiber layer (RNFL) thickness was measured using Cirrus optical coherence tomography (OCT), and coefficient of determinations for VF and OCT parameters were calculated and compared using Akaike information criteria. 740 eyes (including 68 healthy, 262 glaucoma suspects, and 410 glaucoma) of 370 participants were evaluated. No significant differences were seen in mean deviation and visual field index between the two perimeters (P > 0.05). A stronger association between VF mean sensitivity (dB or 1/L) and circumpapillary RNFL was found for TEMPO (adjusted R2 = 0.25; Akaike information criteria [AIC] = 5235.5 for dB, and adjusted R2 = 0.29; AIC = 5200.8 for 1/L, respectively) compared to HFA (adjusted R2 = 0.22; AIC = 5263.9 for dB, and adjusted R2 = 0.22; AIC = 5262.7 for 1/L, respectively). Measurement time was faster for TEMPO compared to HFA (261 s vs. 429 s, P < 0.001). Further investigations are needed to assess the long-term monitoring potential of this binocular VF test.

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.

Comparison of the TEMPO Binocular Perimeter and Humphrey Field Analyzer

This study compared between TEMPO, a new binocular perimeter, with the Humphrey Field Analyzer (HFA). Patients were tested with both TEMPO 24 - 2 AIZE-Rapid and HFA 24 - 2 SITA-Fast in a randomized sequence on the same day. Using a mixed-effects model, visual field (VF) parameters and reliability indices were compared. Retinal nerve fiber layer (RNFL) thickness was measured using Cirrus OCT, and coefficient of determinations for visual field and OCT parameters were calculated and compared using Akaike information criteria. 740 eyes (including 68 healthy, 262 glaucoma suspects, and 410 glaucoma) of 370 participants were evaluated. No significant differences were seen in mean deviation and visual field index between the two perimeters (P > 0.05). A stronger association between VF mean deviation and circumpapillary RNFL was found for TEMPO (adjusted R2 = 0.28; AIC = 5210.9) compared to HFA (adjusted R2 = 0.26; AIC = 5232.0). TEMPO had better reliability indices (fixation loss, false positive, and false negative) compared to HFA (all P < 0.05). Measurement time was faster for TEMPO compared to HFA (261sec vs. 429sec, P < 0.001). Further investigations are needed to assess the long-term monitoring potential of this binocular VF test.

Diagnostic accuracy of an iPad application for detection of visual field defects

BACKGROUND/OBJECTIVES

Tablet-based perimetry could be used to test for glaucomatous visual field defects in settings without easy access to perimeters, although few studies have assessed diagnostic accuracy of tablet-based tests. The goal of this study was to determine the diagnostic accuracy of iPad perimetry using the visualFields Easy application.

SUBJECTS/METHODS

This was a prospective, cross-sectional study of patients undergoing their first Humphrey Field Analyser (HFA) visual field test at a glaucoma clinic in India. Participants underwent 24-2 SITA Standard HFA testing and iPad-based perimetry with the visualFields Easy application. Reference standards for both visual field loss and suspected glaucoma were determined by ophthalmologist review of HFA results and optic disc photographs. Receiver operating characteristic curves were constructed to assess diagnostic accuracy at various test thresholds.

RESULTS

203 eyes from 115 participants were included, with 82 eyes classified as moderate or worse glaucoma. iPad perimetry had an area under the receiver operating characteristic (AUROC) curve of 0.64 (95% CI 0.57 to 0.71) for detection of any visual field defect relative to HFA and an AUROC of 0.68 (0.59 to 0.76) for detection of moderate or worse glaucoma relative to ophthalmologist examination. At a set specificity of 90%, the sensitivity of iPad perimetry for detection of moderate or worse glaucoma was 35% (22-48%).

CONCLUSIONS

iPad perimetry using the visualFields Easy application had inadequate diagnostic accuracy to be used as a screening tool for glaucoma in this South Indian population.

Kinetic Perimetry on Virtual Reality Headset

OBJECTIVE

We present a portable automatic kinetic perimeter based on a virtual reality (VR) headset device as an innovative and alternative solution for the screening of clinical visual fields. We compared the performances of our solution with a gold standard perimeter, validating the test on healthy subjects.

METHODS

The system is composed of an Oculus Quest 2 VR headset with a clicker for participant response feedback. An Android app was designed in Unity to generate moving stimuli along vectors, following a standard Goldmann kinetic perimetry approach. Sensitivity thresholds are obtained by moving centripetally three different targets (V/4e, IV/1e, III/1e) along 24 or 12 vectors from an area of non-seeing to an area of seeing and then transmitted wirelessly to a PC. A Python real-time algorithm processes the incoming kinetic results and displays the hill of vision in a two-dimensional map (isopter). We involved 21 subjects (5 males and 16 females, age range 22-73 years) for a total of 42 eyes tested with our proposed solution, and results were compared with a Humphrey visual field analyzer to test reproducibility and efficacy.

RESULTS

isopters generated with the Oculus headset were in good agreement with those acquired with a commercial device (Pearson's correlation values r > 0.83 for each target).

CONCLUSIONS

we demonstrate the feasibility of VR kinetic perimetry by comparing performances between our system and a clinically used perimeter in healthy subjects.

SIGNIFICANCE

proposed device leads the way for a portable and more accessible visual field test, overcoming challenges in current kinetic perimetry practices.

Biochemical-molecular-genetic biomarkers in the tear film, aqueous humor, and blood of primary open-angle glaucoma patients

Introduction

Glaucoma is a chronic neurodegenerative disease, which is the leading cause of irreversible blindness worldwide. As a response to high intraocular pressure, the clinical and molecular glaucoma biomarkers indicate the biological state of the visual system. Classical and uncovering novel biomarkers of glaucoma development and progression, follow-up, and monitoring the response to treatment are key objectives to improve vision outcomes. While the glaucoma imaging field has successfully validated biomarkers of disease progression, there is still a considerable need for developing new biomarkers of early glaucoma, that is, at the preclinical and initial glaucoma stages. Outstanding clinical trials and animal-model study designs, innovative technology, and analytical approaches in bioinformatics are essential tools to successfully uncover novel glaucoma biomarkers with a high potential for translation into clinical practice.

Methods

To better understand the clinical and biochemical-molecular-genetic glaucoma pathogenesis, we conducted an analytical, observational, and case-comparative/control study in 358 primary open-angle glaucoma (POAG) patients and 226 comparative-control individuals (CG) to collect tears, aqueous humor, and blood samples to be processed for identifying POAG biomarkers by exploring several biological pathways, such as inflammation, neurotransmitter/neurotrophin alteration, oxidative stress, gene expression, miRNAs fingerprint and its biological targets, and vascular endothelial dysfunction, Statistics were done by using the IBM SPSS 25.0 program. Differences were considered statistically significant when p ≤ 0.05.

Results

Mean age of the POAG patients was 70.03 ± 9.23 years, and 70.62 ± 7.89 years in the CG. Malondialdehyde (MDA), nitric oxide (NO), interleuquin (IL)-6, endothelin-1 (ET-1), and 5 hydroxyindolacetic acid (5-HIAA), displayed significantly higher levels in the POAG patients vs. the CG (p < 0.001). Total antioxidant capacity (TAC), brain derived neurotrophic factor (BDNF), 5-hydroxy tryptamine (5-HT), solute carrier family 23-nucleobase transporters-member 2 (SLC23A2) gene, and the glutathione peroxidase 4 (GPX4) gene, showed significantly lower levelsin the POAG patients than in the CG (p < 0.001). The miRNAs that differentially expressed in tear samples of the POAG patients respect to the CG were the hsa miR-26b-5p (involved in cell proliferation and apoptosis), hsa miR-152-3p (regulator of cell proliferation, and extracellular matrix expression), hsa miR-30e-5p (regulator of autophagy and apoptosis), and hsa miR-151a-3p (regulator of myoblast proliferation).

Discussion

We are incredibly enthusiastic gathering as much information as possible on POAG biomarkers to learn how the above information can be used to better steer the diagnosis and therapy of glaucoma to prevent blindness in the predictable future. In fact, we may suggest that the design and development of blended biomarkers is a more appropriate solution in ophthalmological practice for early diagnosis and to predict therapeutic response in the POAG patients.

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.

Survey on electronic visual field data transfer practices among Japan Glaucoma Society board members

BACKGROUND

Visual field (VF) testing in combination with a specialized VF analysis software is critical for characterizing and monitoring visual loss in glaucoma. Although performing glaucoma progression analysis requires original VF data rather than printouts or image files, extent of VF data transfer between referring and referred ophthalmologists is unclear. Here, we surveyed glaucoma specialists who belong to the Japan Glaucoma Society (JGS).

METHODS

An internet survey of daily practice patterns regarding electronic VF data transfer at the time of glaucoma referrals (referring/referred) was sent to all 50 JGS board members. The survey consisted with 11 questionnaires, and the response rate was 100%.

RESULTS

The respondents included 33 university hospital ophthalmologists (66%) (Q1), and those scattered throughout Japan (Q2). All respondents used Humphrey Visual Filed Analyzer (HFA) (Q3) and at least one of a VF progression analysis software (Q4). Ten respondents (20%) actively transferred electronic VF data, while 40 (80%) did not (Q5). The major reasons for not actively transferring data electronically were that there was no support for data transfer by neighboring (n = 26, 65%) and/or own (25, 63%) institutes (Q6). All 40 inactive respondents responded that electronic data transfer is ideal (Q7). All 10 active respondents transferred data using USB flash memory (Q8). Of the 10 active respondents, seven (70%) reported that the percentage of referral letters accompanying electronic VF data in a format that allows for progression analysis from the beginning was less than 25% (Q9). When the referral letters did not accompany the electronic VF data, four (40%) reported that they further requested the data transfer in < 25% of cases (Q10). When the 10 active respondents were requested to transfer data, six (60%) had experienced rejection due to various reasons (Q11).

CONCLUSION

An internet survey showed that 80% of the JGS board members were not actively transferring VF data mainly because of the absence of a system in place at institutions for sending and receiving data, although they feel that the electronic VF data transfer is ideal. The results provide basic data for future discussions on the promotion of the VF data transfer.

Combined use of coenzyme Q10 and citicoline: A new possibility for patients with glaucoma

Glaucoma is the leading cause of irreversible blindness worldwide. Several risk factors have been involved in the pathogenesis of the disease. By now, the main treatable risk factor is elevated intraocular pressure. Nevertheless, some patients, whose intraocular pressure is considered in the target level, still experience a progression of the disease. Glaucoma is a form of multifactorial ocular neurodegeneration with complex etiology, pathogenesis, and pathology. New evidence strongly suggests brain involvement in all aspects of this disease. This hypothesis and the need to prevent glaucomatous progression led to a growing interest in the pharmacological research of new neuroprotective, non-IOP-lowering, agents. The aim of this paper is to report evidence of the usefulness of Coenzyme Q10 and Citicoline, eventually combined, in the prevention of glaucomatous neurodegeneration.

Application and Validation of LUXIE: A Newly Developed Virtual Reality Perimetry Software

PURPOSE

To report the application of LUXIE and validate its reliability by comparing the test results with those of Humphrey Field Analyzer 3 (HFA3).

METHODS

In this pilot study, we prospectively recruited participants who had received HFA3 SITA standard 30-2 perimetry and tested them with LUXIE on the same day. LUXIE is a software designed for visual field testing cooperating with HTC Vive Pro Eye, a head-mounted virtual reality device with an eye-tracking system. The test stimuli were synchronized with eye movements captured by the eye-tracking system to eliminate fixation loss. The global, hemifields, quadrants, glaucoma hemifield test (GHT) sectors, and point-by-point retinal sensitivities were compared between LUXIE and HFA3. All participants were asked to fill out a post-test user survey.

RESULTS

Thirty-eight participants with 65 eyes were enrolled. LUXIE demonstrated good correlations with HFA3 in global (r = 0.81), superior hemifield (r = 0.77), superonasal, superotemporal, and inferonasal quadrants (r = 0.80, 0.78, 0.80). The user survey showed that participants were more satisfied with LUXIE in operating difficulty, comfortability, time perception, concentration, and overall satisfaction.

CONCLUSIONS

LUXIE demonstrated good correlations with HFA3. Fixation loss could be eliminated in LUXIE with the eye-tracking system. The application of virtual reality devices such as the HTC Vive Pro Eye makes telemedicine and even home-based self-screening visual field tests possible.

KEY MESSAGES

1. Virtual reality perimetry is a developing technology that has the potential in telemedicine, and home self-screening visual field tests. 2. LUXIE demonstrated good correlations with Humphrey Field Analyzer 3 in visual field retinal sensitivities.

Visually driven functional MRI techniques for characterization of optic neuropathy

Optic neuropathies are conditions that cause disease to the optic nerve, and can result in loss of visual acuity and/or visual field defects. An improved understanding of how these conditions affect the entire visual system is warranted, to better predict and/or restore the visual loss. In this article, we review visually-driven functional magnetic resonance imaging (fMRI) studies of optic neuropathies, including glaucoma and optic neuritis (ON); we also discuss traumatic optic neuropathy (TON). Optic neuropathy-related vision loss results in fMRI deficit within the visual cortex, and is often strongly correlated with clinical severity measures. Using predominantly flickering checkerboard stimuli, glaucoma studies indicated retinotopic-specific cortical alteration with more prominent deficits in advanced than in early glaucoma. Some glaucoma studies indicate a reorganized visual cortex. ON studies have indicated that the impacted cortical areas are briefly hyperactive. For ON, brain deficits are greater in the acute stages of the disease, followed by (near) normalization of responses of the LGN, visual cortex, and the dorsal visual stream, but not the ventral extrastriate cortex. Visually-driven fMRI is sensitive, at least in ON, in discriminating patients from controls, as well as the affected eye from the fellow eye within patients. The use of a greater variety of stimuli beyond checkerboards (e.g., visual motion and object recognition) in recent ON studies is encouraging, and needs to continue to disentangle the results in terms of change over time. Finally, visually-driven fMRI has not yet been applied in TON, although preliminary efforts suggest it may be feasible. Future fMRI studies of optic neuropathies should consider using more complex visual stimuli, and inter-regional analysis methods including functional connectivity. We suggest that a more systematic longitudinal comparison of optic neuropathies with advanced fMRI would provide improved diagnostic and prognostic information.

Study to Identify and Evaluate Predictor Factors for Primary Open-Angle Glaucoma in Tertiary Prophylactic Actions

The aim of this study is to develop a predictive model with several explanatory variables that can guide ophthalmologists to make a more objective assessment of the evolution of open-angle glaucoma (OAG) during tertiary prevention. Objectives: The evaluation of risk factors and different predictors of symptom progression between patients with POAG and non-glaucoma patients (NG), as well as between primary open-angle glaucoma with high intraocular pressure (POAG) and primary open-angle glaucoma with normal intraocular pressure (NTG), in tertiary prophylactic activities. Methods: This research is an analytical epidemiological study of a prospective cohort. For the study, we took into account personal medical history, physical ophthalmological examination, intraocular pressure (IOP) values, and visual field (VF) parameters, examined with the Opto AP-300 Automated Perimeter using the “fast threshold” strategy. The results of gonioscopy were inconsistently recorded; they were not considered in the study due to missing values, the processing of which would have seriously distorted the statistical analysis. Ophthalmological examination was completed with a dichotomous questionnaire entitled “Symptom Inventory”, made according to the accusations of patients resulting from a “focus group” study. The study was carried out in the ophthalmology office within the Integrated Outpatient Clinic of the Emergency Clinical Hospital of Oradea, Bihor County (IOCECHO) between January−December 2021. The threshold of statistical significance was defined for p value < 0.05. The obtained results were statistically processed with specialized software SPSS 22. Results: The study included 110 people, of which 71 (64.54%) had POAG (IOP > 21 mmHg) and 39 people (35.46%) had NTG (IOP < 21 mmHg), the two groups being statistically significantly different (χ2 = 9.309, df = 1, p = 0.002). For the POAG group, glaucomatous loss was early, AD < −6 dB, according to the staging of glaucomatous disease, HODAPP classification. In addition, the groups of POAG and NTG patients was compared with a group of 110 NG patients, these three groups being statistically significantly different (χ2 = 34.482, df = 2, p = 0.000). Analysis of confounding factors (age, sex, residence, marital status) shows a statistically significant relationship only for age (F = 2.381, df = 40, p = 0.000). Sex ratio for the study groups = 5.11 for OAG and =5.87 for NG. After treatment (prostaglandin analogues and neuroprotective drugs) IOP decreased statistically significantly for both POAG and NTG. Conclusions: this study identified possible predictors of OAG, at the 5% level (risk factors and symptoms as independent variables) using a dichotomous questionnaire tool with a complementary role in tertiary prophylactic activities. The implementation of the focus group interview results as a socio-human research technique will be supportive to clinicians.

Hyperglycemia induces retinal ganglion cell endoplasmic reticulum stress to the involvement of glaucoma in diabetic mice

Glaucoma is a neurodegenerative disease leading to visual loss. Since glaucoma is associated with chronic renal diseases (RDs) their rate is higher in patients with RDs, and end-stage RDs (ESRDs) than in the general population and kidney transplant recipients.

OBJECTIVE

To explore the molecular mechanism of diabetic internal environment in regulating the endoplasmic reticulum stress of the retinal ganglion cells (RGCs).

METHODS

Thirty-six SPF grade type 2 diabetes models were divided into 3 groups: Diabetes mellitus (DM), DM + glaucoma and 4-phenylbutyric acid-DM (4-PBA-DM) + glaucoma group. C57BL6 mice of the same week age were taken as the negative control (NC) group. The morphology of RGCs and their axon in the 4 groups were labeled by fluorescent reactive dye Dil. The apoptosis situation of RGCs was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay. The protein expression values of RTN4IP1, Protein kinase R-like endoplasmic reticulum kinase (PERK), eukaryotic initiation factor 2A (eIF2a) and X-box-binding Protein 1 (XBP1) were determined by western blot. The relative mRNA levels of cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP), Caspase12 and Bax were determined by quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

Glaucoma promotes the apoptosis of RGCs. The protein expression values of RTN4IP1, PERK and XBP1 in DM mouse models with glaucoma were much higher compared to only DM mouse models. Further injection of endoplasmic reticulum stress inhibitor 4-PBA decreased the expression values. The relative mRNA levels of CHOP, Cysteine aspartic acid specific protease12 (Caspase12) and BCL2-associated X protein (Bax) in DM + glaucoma were significantly higher compared to those in DM group. Further injection of endoplasmic reticulum stress inhibitor 4-PBA decreased the mRNA levels.

CONCLUSION

Endoplasmic reticulum stress (ERS) is the underlying cause of glaucoma, which could promote the apoptosis of RGCs in diabetic mice.

Corneal Hysteresis, Intraocular Pressure, and Progression of Glaucoma: Time for a “Hyst-Oric” Change in Clinical Practice?

It is known that as people age their tissues become less compliant and the ocular structures are no different. Corneal Hysteresis (CH) is a surrogate marker for ocular compliance. Low hysteresis values are associated with optic nerve damage and visual field loss, the structural and functional components of glaucomatous optic neuropathy. Presently, a range of parameters are measured to monitor and stratify glaucoma, including intraocular pressure (IOP), central corneal thickness (CCT), optical coherence tomography (OCT) scans of the retinal nerve fibre layer (RNFL) and the ganglion cell layer (GCL), and subjective measurement such as visual fields. The purpose of this review is to summarise the current evidence that CH values area risk factor for the development of glaucoma and are a marker for its progression. The authors will explain what precisely CH is, how it can be measured, and the influence that medication and surgery can have on its value. CH is likely to play an integral role in glaucoma care and could potentially be incorporated synergistically with IOP, CCT, and visual field testing to establish risk stratification modelling and progression algorithms in glaucoma management in the future.

Detection of Intraocular Hypertension during Opportunity Screening (Check-Up Medical Inspections)

The aim of the study is the early detection of OHT (Ocular hypertension) in patients, in the activity of secondary prophylaxis (opportunity screening-medical check-up), to prevent blindness caused by POAG (Primary Open Angle Glaucoma). In Romania, medical examination of personnel with responsibilities in Transport Safety (TS) is legally regulated, being mandatory as a result of the internal transposition of European legislation in the field. The addressability of the patients for examination was determined by personal choice, depending on the accessibility of the medical service on the profile market (availability and price). The design of the study is epidemiological, observational, descriptive and retrospective. The standardized medical protocol included: personal medical history (anamnesis), physical ophthalmological examination, Intraocular pressure (IOP) measurement and Visual Field (VF) performance, with Automated Perimeter “Optopol PTS 910” through “Fast Threshold” strategy. The specialized medical research was completed with a dichotomous questionnaire entitled “Symptom Inventory”, made according to the recommendations of patients resulting from “Focus group” research. The study was carried out within the “Check-up” type medical controls upon request, only for personnel with positions in Transport Safety (TS), during January−December 2021 at S.C. ARTIMED S.R.L. Oradea, Bihor County. Health analysis was performed for 820 people, of whom 71 people (8.65%) tested positive for IOP > 21 mmHg, (suspected OHT) compared to 749 (91.35%) with normal values (Normal intraocular pressure-NIOP); the two lots being statistically significantly different (x2 = 560.590, df = 1, p = 0.000). The study involved 754 men (92.0%) and 66 women (8.0%), the sex ratio is 11.42 (Exp (B) = 0.782, Sig = 0.558, 95% CI = 0.343−1783; sex is not a significant predictor at the 5% level). The prevalence of OHT was 8.66% for the whole group, 8.48% for men and 10.60% for women. In the screening action for the whole group of patients the following was determined: IOP reference = 20.85 mmHg, Sensitivity (Se) = 91.5% and 1-Specificity (Sp) = 0.073, (Sp = 92.7%). The predictive value of the screening test was: Positive Predictive Value (PPV) = 90.1% and Negative Predictive Value (NPV) = 91.7%; Area under the ROC Curve (Receiver Operating Characteristic) = 0.986, Sig. = 0.000, CI95% = 0.979−0.993. A binary logistical model of a questionnaire was developed to determine the screening parameters which significantly predicted OHT: IOP (OR = 4.154, 95% CI: 3.155−5.469), Age < 40 years (OR = 0.408, 95% CI: 0.239−0.698) and Pattern Defect (PD) (OR = 1.475% CI: 1.130−1.925). The results of this study assess health status through regular medical examinations, and highlight their importance and usefulness in secondary prevention activity. The particularity of this “check-up” type for personnel with attributions in transport safety is based on two essential aspects: the legal obligation to perform it and the fact it is financed by the beneficiary (the employer). In patients suspected of OHT after antiglaucoma treatment, IOP statistically significantly decreased.

Rapid Campimetry-A Novel Screening Method for Glaucoma Diagnosis

One of the most important functions of the retina-the enabling of perception of fast movements-is largely suppressed in standard automated perimetry (SAP) and kinetic perimetry (Goldmann) due to slow motion and low contrast between test points and environment. Rapid campimetry integrates fast motion (=10°/4.7 s at 40 cm patient-monitor distance) and high contrast into the visual field (VF) examination in order to facilitate the detection of absolute scotomas. A bright test point moves on a dark background through the central 10° VF. Depending on the distance to the fixation point, the test point automatically changes diameter (≈0.16° to ≈0.39°). This method was compared to SAP (10-2 program) for six subjects with glaucoma. Rapid campimetry proved to be comparable and possibly better than 10-2 SAP in identifying macular arcuate scotomas. In four subjects, rapid campimetry detected a narrow arcuate absolute scotoma corresponding to the nerve fiber course, which was not identified as such with SAP. Rapid campimetry promises a fast screening method for the detection of absolute scotomas in the central 10° visual field, with a potential for cloud technologies and telemedical applications. Our proof-of-concept study motivates systematic testing of this novel method in a larger cohort.

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.

A deep dive into the latest European Glaucoma Society and Asia-Pacific Glaucoma Society guidelines and their relevance to India

Glaucoma is the second leading cause of blindness in India. Despite advances in diagnosing and managing glaucoma, there is a lack of India-specific clinical guidelines on glaucoma. Ophthalmologists often refer to the European Glaucoma Society (EGS) and Asia-Pacific Glaucoma Society (APGS) guidelines. A group of glaucoma experts was convened to review the recently released EGS guideline (fifth edition) and the APGS guideline and explore their relevance to the Indian context. This review provides the salient features of EGS and APGS guidelines and their utility in Indian scenario. Glaucoma diagnosis should be based on visual acuity and refractive errors, slit-lamp examination, gonioscopy, tonometry, visual field (VF) testing, and clinical assessment of optic nerve head, retinal nerve fiber layer (RNFL), and macula. The intraocular pressure target must be individualized to the eye and revised at every visit. Prostaglandin analogues are the most effective medications and are recommended as the first choice in open-angle glaucoma (OAG). In patients with cataract and primary angle-closure glaucoma (PACG), phacoemulsification alone or combined phacoemulsification and glaucoma surgery are recommended. Trabeculectomy augmented with antifibrotic agents is recommended as the initial surgical treatment for OAG. Laser peripheral iridotomy and surgery in combination with medical treatment should be considered in high-risk individuals aged <50 years. In patients with phakic and PACG, phacoemulsification alone or combined phacoemulsification and glaucoma surgery are recommended. Visual acuity, VF testing, clinical assessment of the optic disc and RNFL, and tonometry are strongly recommended for monitoring glaucoma progression.

Measures of disease activity in glaucoma

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

Aspects of Tertiary Prevention in Patients with Primary Open Angle Glaucoma

The purpose of the study is to assess the health of patients in the activity of tertiary prevention dedicated to preventing blindness caused by POAG (primary glaucoma with open angle and high tension) and NTG (primary glaucoma with open-angle and statistically normal tension-particular form of glaucoma with open angle) and preservation of the remaining visual function. The design of the study is epidemiological, observational, descriptive and retrospective, and uses only the data recorded in the existing records in the archives of the Ophthalmology office within the Integrated Outpatient Clinic of the Emergency Clinical Hospital of Oradea (IOCECHO) during the years 1999-2019 (anamnestic data; objective examination and paraclinical examination: intraocular pressure-IOP and visual field-VF). The methods of the study included the standardized protocol: anamnesis, physical ophthalmological examination, IOP determination, and computerized perimetry with the "Fast Threshold" strategy performed with the "Opto AP-300" perimeter. The obtained results were statistically processed with a specialized software (S.P.S.S.-I.B.M. Statistics version 22). The study examined the available data of 522 patients of which 140 were men (26.8%) and 382 were women (73.2%). The gender ratio was 0.37. In the period 1999-2019, 150,844 people with ophthalmic pathology were consulted in the Ophthalmology office of IOCECHO out of which 522 patients (0.35%) were diagnosed with primitive open-angle glaucoma, 184 people (35.2%) presented high IOP (POAG), and 338 people (64.8%) had statistically normal IOP (NTG). The annual proportion of cases diagnosed with glaucoma in the total number of patients examined was between 0.1% (2005; 2008; 2010) and 2.4% in 2012, when 101 people were detected. In the studied records, no cases of uni- and/or bilateral blindness were mentioned. The mean age of glaucoma patients at the first consultation was 60.81 ± 12.14 years with high frequencies in the 55-69 age groups and at the last consultation it was 66.10 ± 12.47 years with high frequencies in the age groups between 60-74 years. Monitoring and treatment of glaucoma patients was beneficial; IOP decreased statistically significantly: in patients with POAG by 46.16%, from 30.50 ± 7.98 mmHg to 16.42 ± 3.01 mmHg (p = 0.000) and in those with NTG by 17.44%, at 16.39 ± 3.66 mmHg at 13.53 ± 1.92 mmHG (p = 0.000). The duration of treatment and monitoring was on average 5.1 ± 3.4 years, for 184 patients (35.2%) with POAG and 5.1 ± 3.8 years for 338 patients (64.8%) with NTG. Tertiary prevention of glaucoma, by providing specialized care, ensures effective control of IOP and implicitly of the long-term evolution of the disease. IOP is the only modifiable risk factor in patients with POAG and NTG and its decrease prevents the progression of the disease and emphasizes the importance of early diagnosis and treatment. The management of the glaucoma patient consisted of: complete ophthalmological examination (subjective and objective), paraclinical examination with IOP, and VF measurement (valuable ophthalmological diagnostic tool) for disease detection and effective assessment of disease progression in order to improve the process of therapeutic decision making.

Comparison of the SITA Faster-a new visual field strategy with SITA Fast strategy

AIM

To compare visual field defects using the Swedish Interactive Thresholding Algorithm (SITA) Fast strategy with SITA Faster strategy, a newly developed time-saving threshold visual field strategy.

METHODS

Ninety-three participants (60 glaucoma patients and 33 normal controls) were enrolled. One eye from each participant was selected randomly for the study. SITA Fast and SITA Faster were performed using the 24-2 default mode for each test. The differences of visual field defects between the two strategies were compared using the test duration, false-positive response errors, mean deviation (MD), visual field index (VFI) and the numbers of depressed test points at the significant levels of P<5%, <2%, <1%, and <0.5% in probability plots. The correlation between strategies was analyzed. The agreement between strategies was acquired by Bland-Altman analysis.

RESULTS

Mean test durations were 246.0±60.9s for SITA Fast, and 156.3±46.3s for SITA Faster (P<0.001). The test duration of SITA Faster was 36.5% shorter than SITA Fast. The MD, VFI and numbers of depressed points at P<5%, <2%, <1%, and <0.5% in probability plots showed no statistically significant difference between two strategies (P>0.05). Correlation analysis showed a high correlation for MD (r=0.986, P<0.001) and VFI (r=0.986, P<0.001) between the two strategies. Bland-Altman analysis showed great agreement between the two strategies.

CONCLUSION

SITA Faster, which saves considerable test time, has a great test quality comparing to SITA Fast, but may be not directly interchangeable.

Caffeine abrogates oxidative stress imbalance: Its implication on lateral geniculate nucleus and visual cortex following hyaluronic acid exposure

This study assessed the role of caffeine (adenosine receptor antagonist) in the Lateral geniculate body as well as the primary visual cortex of hyaluronic acid model of glaucomatous rats. Twenty (20) male Long evans rats were randomly divided into four groups with five animals each. This research confirmed that hyaluronic acid (HA) significantly induces elevated intraocular pressure from 18 to 35 mmHg and caffeine had no effect on its reduction to palliate visual impairment; There were a significant increase in the lipid peroxidation and conversely decrease in superoxide level with HA which were attenuated by caffeine. Although, caffeine showed a capability of ameliorating the histopathological changes induced by HA in terms of maintenance of a viable neuronal cell count and significant reduction of tumour necrosis factor-α immune positive cells in the LGB and visual cortex. These findings suggest that caffeine was unable to lower the intraocular pressure after hyaluronic acid exposure but has the ability to restore the antioxidant imbalance via mitigating pro-oxidant mediators and abrogate neurodegeneration.

Asymmetric Functional Impairment of ON and OFF Retinal Pathways in Glaucoma

Purpose

To investigate ON-pathway versus OFF-pathway dysfunction in glaucoma using handheld electroretinography (ERG) with a temporally modulated sinusoidal flicker stimulus.

Design

Cross-sectional study.

Participants

Fifty-nine participants accounting for 104 eyes, comprised of 19 control eyes, 26 glaucoma suspect eyes, and 59 glaucoma eyes.

Methods

Participants underwent portable ERG testing, which included the photopic flash, photopic flicker, photopic negative response stimulus, ON-OFF stimulus, and a custom-written sinusoidal flicker stimulus that was modulated from 50 to 0.3 Hz.

Main Outcome and Measures

The ERG response amplitudes were measured by the handheld ERG. For the custom-written sinusoidal flicker stimulus, we derived and compared the log10 first harmonic frequency response amplitudes. Patient discomfort and fatigue after ERG testing were rated on a scale from 1 to 5.

Results

Baseline demographics were not significantly different between groups, except for ocular characteristics. Analysis was performed adjusting for participant age, sex, race, and dilation status, and the sinusoidal frequency responses were stratified at 10 Hz because higher frequencies are associated with the OFF-pathway, whereas lower frequencies are associated with the ON-pathway. After stratification, glaucoma eyes showed an adjusted decrease of 32.1% at frequencies of more than 10 Hz (95% confidence interval [CI], -51.8% to -4.1%; P = 0.03). For 10 Hz stimulus frequencies or less, an adjusted 11.5% reduction was found (95% CI, -39.5% to 29.1%; P = 0.50). Glaucoma suspect eyes did show a decreased response, but this was not significant at either frequency range. When comparing handheld ERG with traditional visual field assessments, participants found the handheld ERG to result in much less discomfort and fatigue.

Conclusions

Our finding that glaucoma participants showed greater decreases in ERG response at higher frequencies supports the hypothesis that the OFF-pathway may be more vulnerable in human glaucoma. Using a handheld ERG device with a sinusoidal flicker stimulus may provide an objective assessment of visual function in glaucoma.

Summation of Temporal L-Cone- and M-Cone-Contrast in the Magno- and Parvocellular Retino-Geniculate Systems in Glaucoma

Purpose

The purpose of this study was to characterize summation of temporal L- and M-cone contrasts in the parvo- (P-) and magnocellular (M-) pathways in glaucoma and the relationship between the respective temporal contrast sensitivities (tCS) and clinical parameters.

Methods

Perifoveal tCS to isolated or combined L- and M-cone contrasts (with different contrast ratios, and therefore different luminance and chromatic components) were measured at different temporal frequencies (at 1 or 2 Hz and at 20 Hz) using triple silent substitution in 73 subjects (13 healthy, 25 with glaucoma, and 35 with perimetric glaucoma). A vector summation model was used to analyze whether perception was driven by the P-pathway, the M-pathway, or both. Using this model, L- and M-cone input strengths (A_L, A_M) and phase differences between L- and M-cone inputs were estimated.

Results

Perception was always mediated by the P-pathway at low frequencies, as indicated by a median phase angle of 179.84 degrees (cone opponency) and a median A_L/A_M ratio of 1.04 (balanced L- and M-cone input strengths). In contrast, perception was exclusively mediated by the M-pathway at higher frequencies (input strength not balanced: A_L/A_M = 2.94, median phase angles = 130.17 degrees). Differences in phase were not significant between diagnosis groups (Kruskal-Wallis = 0.092 for P- and 0.35 for M-pathway). We found differences between groups only for the M-pathway (L-cone tCS deviations at 20 Hz were significantly lower in the patients with glaucoma P = 0.014, with a strong tendency in M-cones P = 0.049). L-cone driven tCS deviations at 20 Hz were linearly correlated with perimetric mean defect (MD) and quadratically correlated with retinal nerve fiber layer (RNFL) thickness.

Conclusions

Unaltered phase angles between L- and M-cone inputs in glaucoma indicated intact temporal processing. Only in the M-pathway, contrast sensitivity deviations were closely related to diagnosis group, MD, and RNFL thickness, indicating M-pathway involvement.

Functional characteristics of glaucoma related arcuate defects seen on OCT en face visualisation of the retinal nerve fibre layer

Purpose

To assess continuity of perimetric defects corresponding to arcuate defects seen on optical coherence tomography (OCT) en face reflectance images of the retinal nerve fibre layer (RNFL) in patients with glaucoma.

Methods

Seven patients with glaucoma who had arcuate structural defects on OCT RNFL en face images were recruited. Static suprathreshold stimuli were presented along different meridians to localise perimetric defects in the corresponding hemifield. Then two contrasts, one 6 dB greater than the other, were used with kinetic perimetry to assess the slope of the defect. Findings with kinetic and 24‐2 perimetry were compared.

Results

Static perimetry found that regions of perimetric abnormality spatially corresponded with the regions of en face RNFL hyporeflectivity. Kinetic perimetry found that the slopes of the edges of the defects ranged from 3–12 dB degree⁻¹, and that the functional abnormalities were continuous with the physiologic blind spot even when the 24‐2 protocol only showed paracentral defects.

Conclusions

Perimetric abnormalities and arcuate RNFL en face defects were spatially correspondent. Perimetric testing guided by OCT en face reflectance images can reveal greater functional detail of glaucomatous abnormality than 24‐2 testing.

Impact of binocular integrated visual field defects on healthy related quality of life in glaucoma

To investigate the impact of different types of binocular integrated visual field defects on the quality of life in glaucoma.Ninety-six patients with primary glaucoma were divided into 5 groups with 25, 24, 11, 15, and 21 patients according to types of the binocular integrated visual field (BVF) defects. The criteria for BVF grouping included mild visual field defect in binocular eyes, mild visual field defect in 1 eye and moderate or advanced defect in the other, moderate and non-overlapping visual field defect in both eyes, overlapping and moderate visual field defect in binocular eyes, and severe defect in both eyes, respectively. The visual field (VF) evaluation was based on H-P-A visual field grading system. Visual acuity, visual field tests and Glaucoma Quality of Life-15 Questionnaire (GQL-15) were performed for enrolled patients, and binocular visual field results were integrated. The changes and correlations of the Visual field index values and quality of life scores were compared among the 5 groups. The main factors affecting the quality of life in glaucoma were analyzed by multiple regression analysis.The best binocular integrated visual field index (BVFI) and optimal quality of life were observed in group A. The BVFI of group B was better than that of group C or group D, but the peripheral vision glare and dark adaptation were worse. No significant difference was noted between group C and group D in terms of BVFI. However, the glare and dark adaptation in group C were better than that in group D. The BVFI was the lowest and the quality of life was the worst in group E. In all, BVFI and decibels (dB) values were negatively correlated with GQL-15 scores and positively correlated with patients' quality of life.Binocular integrated visual field accurately reflects the visual function in glaucoma. Higher binocular integrated visual field indices represent a better quality of life for patients with glaucoma. Mild to moderate synchronous or complementary binocular VF defects had a slight effect on the quality of life, while severe and non-compensated VF loss significantly impacts on quality of life in glaucoma patients.

Preliminary Report on a Novel Virtual Reality Perimeter Compared With Standard Automated Perimetry

PRECIS

The VisuALL head-mounted perimetry in normal subjects and glaucoma patients had a moderate to strong correlation with the Humphrey Field Analyzer (HFA).

PURPOSE

Visual field testing has a vital role in diagnosing and managing glaucoma. The current clinical practice relies on large, table-based testing units. This study investigated the performance of a novel virtual reality head-mounted visual perimetry device (VisuALL), in normal and glaucoma patients.

METHODS

This prospective observational study was conducted on 50 eyes of 25 healthy subjects (normal group) and 52 eyes of 26 patients with a controlled mild or moderate stage of glaucoma (glaucoma group). All participants had visual field testing with VisuALL and the HFA (24-2, Swedish Interactive Threshold Algorithm). The mean sensitivity of the whole visual field and each quadrant were compared between both machines and the receiver operating characteristic was used to compare the diagnostic abilities and the Bland-Altman plot to evaluate the agreement of the 2 perimeters.

RESULTS

The global mean sensitivity of the VisuALL and the HFA correlated significantly in both normal (r=0.5, P=0.001) and glaucoma (r=0.8, P<0.001) groups. The mean sensitivity of all quadrants also correlated significantly in both groups. The VisuALL mean sensitivity had a greater (0.98) receiver operating characteristic curve than HFA (0.93) mean sensitivity (P=0.06) in discriminating normal versus glaucoma.

CONCLUSION

There was an excellent correlation between the VisuALL and the Standard Automated Perimetry in normal and glaucoma patients and VisuALL showing high diagnostic performance.

Evaluation of the external validity of a joint structure-function model for monitoring glaucoma progression

The dynamic structure–function (DSF) model was previously shown to have better prediction accuracy than ordinary least square linear regression (OLSLR) for short series of visits. The current study assessed the external validity of the DSF model by testing its performance in an independent dataset (Ocular Hypertension Treatment Study–Confocal Scanning Laser Ophthalmoscopy [OHTS–CSLO] ancillary study; N = 178 eyes), and also on different test parameters in a sample selected from the Diagnostic Innovations in Glaucoma Study or the African Descent and Glaucoma Evaluation Study (DIGS/ADAGES). Each model was used to predict structure–function paired data at visits 4–7. The resulting prediction errors for both models were compared using the Wilcoxon signed-rank test. In the independent dataset, the DSF model predicted rim area and mean sensitivity paired measurements more accurately than OLSLR by 1.8–5.5% (p ≤ 0.004) from visits 4–6. Using the DIGS/ADAGES dataset, the DSF model predicted retinal nerve fiber layer thickness and mean deviation paired measurements more accurately than OLSLR by 1.2–2.5% (p ≤ 0. 007). These results demonstrate the external validity of the DSF model and provide a strong basis to develop it into a useful clinical tool.

Probing ON and OFF Retinal Pathways in Glaucoma Using Electroretinography

Glaucoma is a progressive neurodegenerative disease involving damage and eventually death of retinal ganglion cells (RGCs) that comprise the optic nerve. This review summarizes current understanding of specific RGC type vulnerability in glaucoma and how electroretinography (ERG) may provide an objective measure of these functional perturbations. There is building evidence to suggest that ON RGCs, which respond to light increments, may be more resilient to elevated intraocular pressure and glaucoma, whereas OFF RGCs, which respond to light decrements, may be more susceptible. ERG experiments in nonhuman primates and mice have also shown that the ON- and OFF-pathways can be separated using a variety of techniques such as pattern ERG and the photopic negative response. Another ERG paradigm of interest to separate the ON and OFF responses is a flicker stimulus at varying temporal frequencies. Response to lower temporal frequencies is associated with the ON-pathway, and ERG response to higher frequencies is associated with the OFF-pathway. In mice, experimental glaucoma models have shown greater decreases in ERG response at higher frequencies, suggesting that the OFF-pathway is more susceptible. We also summarize current clinical ERG protocols used for glaucoma and discuss innovations for developing new types of stimuli that can further separate the ON- and OFF-pathways. Applying these novel paradigms that distinguish ON- and OFF-pathways may ultimately improve glaucoma diagnostics and monitoring of glaucoma progression.

Discovery and clinical translation of novel glaucoma biomarkers

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

Impact of Visual Field Testing on Intraocular Pressure Change Trends in Healthy People and Glaucoma Patients

PURPOSE

To compare the impact of visual field (VF) testing on intraocular pressure (IOP) change trends between healthy subjects and glaucoma patients.

METHODS

We recruited healthy volunteer subjects who did not have previous ocular diseases and open-angle glaucoma patients who were medically controlled well. IOP in both eyes of each participant was measured by using a noncontact tonometer at five time points: before, immediately after (0 minute), and 10, 30, and 60 minutes after the standard automated perimetry. Repeated measures ANOVA was used to analyze the effect of VF testing on IOP change trends in healthy and glaucoma eyes.

RESULTS

Forty healthy subjects (80 eyes) and 31 open-angle glaucoma patients (62 eyes) were included for the study. The baseline IOP of healthy and glaucoma eyes was 16.11 ± 3.01 mmHg and 15.78 ± 3.57 mmHg, respectively. After the VF testing, the IOP in healthy eyes was decreased by 1.5% at 0 minute, 6.5% at 10 minutes (P < 0.001), 6.6% at 30 minutes (P < 0.001), and 7.0% at 1 hour (P < 0.001), indicating that this reduction was sustained for at least 1 hour. However, the IOP in glaucoma eyes was increased by 12.7% at 0 minute (P < 0.001) and, then, returned towards initial values 1 hour after the VF testing.

CONCLUSIONS

IOP change trends after VF field testing between healthy subjects and glaucoma patients were quite different. VF testing led to a mild and relatively sustained IOP decrease in healthy subjects, whereas IOP in open-angle glaucoma patients tended to significantly increase immediately after VF testing and, then, returned to pretest values after 1 hour. These findings indicate that the factors of VF testing should be considered in the clinical IOP measurements.

Comparison between two fast threshold strategies: SPARK and SITA in normal subjects

BACKGROUND

Numerous fast threshold strategies have been developed in perimetry which use maximum likelihood approaches to estimate the threshold. A recent approach to threshold estimation has been developed estimating the threshold from a limited number of test points which further reduces examination time. This strategy, SPARK, has not been compared to the SITA strategy. The aim of this study was to compare SPARK with SITA in a normal cohort to evaluate within and between strategy agreement in threshold estimates.

METHODS

A total of 83 normal subjects each underwent two visual field examinations with SITA and SPARK on two separate occasions on a randomly selected eye. The eye examined and the order of strategy examined first was randomised but remained constant over the two perimetry visits.

RESULTS

Visual field examination with SPARK Precision was on average 33% faster than SITA Standard. A positive correlation between group mean sensitivities of SITA Standard and SPARK Precision (rho = 0.713, p < 0.001) was found. In total, 95% of stimulus locations were located within the 95% limits of agreement and linear regression on the differences in sensitivities showed no statistically significant proportional bias (t = 1.713, p = 0.09). Pointwise analysis showed SITA Standard had significantly larger variability for individual stimulus locations examined over two visits when compared to SPARK (t = 9.175, p < 0.001).

CONCLUSION

The clinical examination of SPARK yields a sensitivity profile similar to SITA but in a faster examination time. The lower threshold variability of SPARK may be as a result of data smoothing in the threshold estimation process.

Management of Retinitis Pigmentosa via Platelet-Rich Plasma or Combination with Electromagnetic Stimulation: Retrospective Analysis of 1-Year Results

PURPOSE

To investigate whether the natural progression rate of retinitis pigmentosa can be decreased by subtenon autologous platelet-rich plasma application alone or combination with retinal electromagnetic stimulation.

METHODS

The study includes retrospective analysis of 60 patients with retinitis pigmentosa. Patients constitute three groups with similar demographic characteristics: the combined management group (group 1) consists of 20 patients with retinitis pigmentosa (40 eyes) who received combined retinal electromagnetic stimulation and subtenon platelet-rich plasma; the subtenon platelet-rich plasma-only group (group 2) consisted of 20 patients with retinitis pigmentosa (40 eyes); the natural course (control) group (group 3) consists of 20 patients with retinitis pigmentosa (40 eyes) who did not receive any treatment. Horizontal and vertical ellipsoid zone width, fundus perimetry deviation index, and best corrected visual acuity changes were compared within and between groups after a 1-year follow-up period.

RESULTS

Detected horizontal ellipsoid zone percentage changes were + 1% in group 1, - 2.85% in group 2, and - 9.36% in group 3 (Δp 1 > 2 > 3). Detected vertical ellipsoid zone percentage changes were + 0.34% in group 1, - 3.05% in group 2, and - 9.09% in group 3 (Δp 1 > 2 > 3). Detected fundus perimetry deviation index percentage changes were + 0.05% in group 1, - 2.68% in group 2, and - 8.78% in group 3 (Δp 1 > 2 > 3).

CONCLUSION

Platelet-rich plasma is a good source of growth factors, but its half-life is 4-6 months. Subtenon autologous platelet-rich plasma might more effectively slow down photoreceptor loss when repeated as booster injections and combined with retinal electromagnetic stimulation.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT04252534.

The Assessment of Visual Function and Functional Vision

The complete assessment of vision-related abilities should consider visual function (the performance of components of the visual system) and functional vision (visual task-related ability). Assessment methods are highly dependent upon individual characteristics (eg, the presence and type of visual impairment). Typical visual function tests assess factors such as visual acuity, contrast sensitivity, color, depth, and motion perception. These properties each represent an aspect of visual function and may impact an individual's level of functional vision. The goal of any functional vision assessment should be to measure the visual task-related ability under real-world scenarios. Recent technological advancements such as virtual reality can provide new opportunities to improve traditional vision assessments by providing novel objective and ecologically valid measurements of performance, and allowing for the investigation of their neural basis. In this review, visual function and functional vision evaluation approaches are discussed in the context of traditional and novel acquisition methods.

Robot Assistants for Perimetry: A Study of Patient Experience and Performance

Purpose

People enjoy supervision during visual field assessment, although resource demands often make this difficult. We evaluated outcomes and subjective experience of methods of receiving feedback during perimetry, with specific goals to compare a humanoid robot to a computerized voice in participants with minimal prior perimetric experience. Human feedback and no feedback also were compared.

Methods

Twenty-two younger (aged 21-31 years) and 18 older (aged 52-76 years) adults participated. Visual field tests were conducted using an Octopus 900, controlled with the Open Perimetry Interface. Participants underwent four tests with the following feedback conditions: (1) human, (2) humanoid robot, (3) computer speaker, and (4) no feedback, in random order. Feedback rules for the speaker and robot were identical, with the difference being a social interaction with the robot before the test. Quantitative perimetric performance compared mean sensitivity (dB), fixation losses, and false-positives. Subjective experience was collected via survey.

Results

There was no significant effect of feedback type on the quantitative measures. For younger adults, the human and robot were preferred to the computer speaker (P < 0.01). For older adults, the experience rating was similar for the speaker and robot. No feedback was the least preferred option of 77% younger and 50% older adults.

Conclusions

During perimetry, a social robot was preferred to a computer speaker providing the same feedback, despite the robot not being visible during the test. Making visual field testing more enjoyable for patients and operators may improve compliance and attitude to perimetry, leading to improved clinical outcomes.

Translational Relevance

Our data suggest that humanoid robots can replace some aspects of human interaction during perimetry and are preferable to receiving no human feedback.

Analysis of pattern electroretinogram signals of early primary open-angle glaucoma in discrete wavelet transform coefficients domain

PURPOSE

To evaluate discrete wavelet transform coefficients and identify descriptors of pattern electroretinogram (PERG) waveforms in order to determine PERG characteristics for optimizing the diagnosis of early primary open-angle glaucoma (POAG).

METHODS

Pattern electroretinogram was performed in 30 normal eyes and 30 eyes with primary open-angle glaucoma according to the ISCEV protocol. The check size was 0.8° and 16°, and the color was black/white in both groups. The results were analyzed in time domain (TD) and discrete wavelet transform (DWT) using the MATLAB software. The mean value, standard deviation, and relative energy of level 6 and 7 detail coefficients (d6, d7) and level 7 approximation coefficients (a7) of Daubechies 4 (db4), Daubechies 8 (db8), Symlet 5 (sym5), Symlet 7 (sym7), and Coiflet 5 (coif5) wavelets were calculated. In all the mentioned wavelets, DWT descriptors were extracted. Signals were reconstructed by inverse DWT. All data obtained by TD and DWT analyses were compared between the two groups.

RESULTS

In both check sizes, a significant attenuation of N95 amplitude was seen in the patient group. The relative energy of a7 of db8 increased significantly in the POAG group in the 0.8° check size. In larger check stimuli, the relative energy of d7 of coif5 decreased significantly and the standard deviation of d7 of sym7 increased markedly in glaucomatous patients (P < 0.05). In small stimuli, N95 descriptor (7N) of db8 had the highest value and showed a significant increase as compared to the POAG group. In the 16° check size, there was no significant difference. A strong correlation was seen between reconstructed signals and originals (r = 0.99).

CONCLUSION

The DWT can quantify PERG responses more accurately. In agreement with TD and wavelet coefficients domain results, 7N of db8 decomposition can be used as a good indicator for early detection of POAG.

Development and validation of a new glaucoma screening test using temporally modulated flicker

PURPOSE

Describing the psychometric characteristics and diagnostic accuracy of the Accelerator 4-Alternative Forced-Choice Flicker Test prototype (A4FTp) for detecting chronic open angle glaucoma (COAG).

METHODS

A4FTp measures temporally-modulated flicker thresholds in regions of the visual field with high susceptibility to glaucomatous loss. We initially evaluated its psychometric properties on 20 normals (aged 33.8 ± 8.5 years) who were tested multiple times over a period of 3 months. All subjects underwent four repetitions for shorter (T8) and longer (T12) staircase termination criteria, to determine the most suitable threshold criterion. Four randomly selected subjects underwent a total of 10 repetitions to study test-retest repeatability and learning effects. To determine its diagnostic accuracy, one eye of 40 participants with COAG and 38 normal controls were tested with the A4FTp in comparison with the Frequency Doubling Technology (FDT; C20-5 programme) and iVue Spectral Domain Optical Coherence Tomography (SD-OCT). Tests were conducted in a random order with results masked to the clinician conducting the reference ophthalmic examination. The accuracy of each test was determined by analysis of the area under the receiver operator characteristic curve (AUROC).

RESULTS

A4FTp flicker thresholds were stable, with standard deviations of only 0.52 decilog (dL) for T8, increasing to 1.32 dL for T12, and no significant flicker sensitivity threshold improvement over the 10 repeat runs. T8 was superior to T12 on several other measures, so it was used for the remaining comparisons. In terms of diagnostic accuracy, the mean AUROC for the three tests were A4FTp [T8 criterion; 0.82, 95% confidence interval (0.73-0.92)]; SD-OCT [any RNFL parameter p < 1% level; 0.90 (0.83-0.97)]; and FDT [one or more locations missed at p < 5% level; 0.91 (0.82-0.96)]. There was no statistical difference in AUROC between A4FTp and SD-OCT (p = 0.18) or FDT (p = 0.12). The A4FTp test duration averaged just over 2 min per eye, taking approximately one-third of the time for completion of the HFA SITA 24-2 algorithm (conducted as part of the reference examination) and twice the time for the suprathreshold FDT.

CONCLUSION

Test accuracy for the A4FTp was comparable to those of the FDT and SD-OCT for the detection of COAG. Time taken to complete the A4FTp was relatively short and initial results are promising. With further refinement, the A4FTp could have a future role in glaucoma detection.