Portable Perimetry Using Eye-Tracking on a Tablet Computer-A Feasibility Assessment

Views and opinions of patients with glaucoma and age-related macular degeneration on vision home-monitoring: a UK-based focus group study

OBJECTIVE

To investigate the views, hopes and concerns of patients living with glaucoma and age-related macular degeneration (AMD) regarding vision home-monitoring.

DESIGN

Qualitative study using focus groups and questionnaires. Participants were given three disease-relevant home-monitoring tests to try. The tests consisted of three visual field tests for the glaucoma groups (Melbourne Rapid Fields, Eyecatcher, Visual Fields Fast) and three acuity and/or contrast-sensitivity tests for AMD groups (Alleye, PopCSF, SpotChecks). Focus group data were thematically analysed.

SETTING

University meeting rooms in London, UK.

PARTICIPANTS

Eight people with glaucoma (five women, median age 74) and seven people with AMD (four women, median age 77) volunteered through two UK-based charities. Participants were excluded if they did not self-report a diagnosis of glaucoma or AMD or if they lived further than a 1-hour travel distance from the university (to ensure minimal travel burden on participants).

RESULTS

Six themes emerged from focus groups, the two most frequently referenced being: 'concerns about home-monitoring' and 'patient and practitioner access to results'. Overall, participants believed home-monitoring could provide patients with a greater sense of control, but also expressed concerns, including: the possibility of home-monitoring replacing face-to-face appointments; the burden placed on clinicians by the need to process additional data; struggles to keep up with requisite technologies; and potential anxiety from seeing worrying results. Most devices were scored highly for usability, though several practical improvements were suggested.

CONCLUSION

Patients with mild-to-moderate glaucoma/AMD expect vision home-monitoring to be beneficial, but have significant concerns about its potential implementation.

Repeatability of Online Circular Contrast Perimetry Compared to Standard Automated Perimetry

PRCIS

Online circular contrast perimetry provides visual field assessment on any computer or tablet with no extra hardware. It has good test repeatability and reliability that is comparable with standard automated perimetry. It holds promise for use in disease screening and surveillance to expand the provision of glaucoma care.

PURPOSE

To evaluate the repeatability of online circular contrast perimetry (OCCP) compared to standard automated perimetry (SAP) in normal participants and patients with stable glaucoma over 18 weeks.

METHODS

Thirty-six participants (13 normal controls and 23 patients with open angle glaucoma) were recruited. OCCP and SAP perimetry tests were performed twice at baseline, then at 6, 12, and 18 weeks. Global perimetric indices were compared between perimetry types and analyzed for short-term and intermediate-term repeatability.

RESULTS

There were no statistically significant changes over time for both OCCP and SAP across all groups for mean deviation (MD), pattern standard deviation, and visual index/visual field index ( P >0.05). Test-retest intraclass correlation coefficients (ICCs) for OCCP MD were excellent at baseline (0.98, 95% CI: 0.89-0.99) and good at 18 weeks (0.88, 95% CI: 0.51-0.98). SAP test-retest ICCs were excellent at baseline (0.94, 95% CI: 0.70-0.99) and 18 weeks (0.97, 95% CI: 0.84-0.99). Inter-test ICCs were good, ranging from 0.84 to 0.87. OCCP testing time was shorter than SAP (5:29 ± 1:24 vs. 6:00 ± 1:05, P <0.001). OCCP had similar false-positive (3.84 ± 3.32 vs. 3.66 ± 4.53, P =0.48) but lower false-negative (0.73 ± 1.52 vs. 4.48 ± 5.00, P <0.001) and fixation loss responses (0.91 ± 1.32 vs. 2.02 ± 2.17, P <0.001).

CONCLUSIONS

OCCP allows visual field assessment on any computer screen with no additional hardware. It demonstrated good repeatability and reliability with similar performance indices to SAP in both the short term and intermediate term. OCCP has the potential to be utilized as a glaucoma screening and surveillance tool for in-clinic and at-home testing, expanding the provision of care.

Development and Validation of an Internet-Based Remote Perimeter (Perimouse)

Purpose

We sought to validate the feasibility of Perimouse, an internet-based remote perimeter that allows for natural fixation and can be performed on most computers via a web page.

Methods

In this cross-sectional study, Perimouse evaluated the visual field of 45 healthy people and 27 patients with primary open-angle glaucoma on a laptop. Participants used a mouse cursor to locate new dots on the screen that were determined by preset saccade vectors. A "click and confirm" strategy was used to eliminate the unwanted visual search. Dot brightness was either fixed at 12 dB in the suprathreshold program (screening program) or variable in the threshold program. We compared Perimouse outcomes with the Humphrey Field Analyzer (HFA) 24-2 Swedish Interactive Testing Algorithm standard program.

Results

In the screening program, Perimouse showed moderate to high concordance with HFA. The intraclass coefficient ranged from 0.58 to 0.86 in different areas of Garway-Heath mapping. In the threshold program, normal subjects had threshold ranging from 19 to 16 dB, presenting sensitivity changes according to the "hill of vision". The test-retest difference was 0.09 dB. Habitual spectacle correction and environmental luminance (2-337 lux) had little impact on the central or peripheral threshold (P > 0.05). The correlation between Perimouse and HFA threshold sensitivity was strong (R = 0.950), although Perimouse mean defect was 4.40 dB higher than the HFA mean defect.

Conclusions

Perimouse is a reliable visual field test that correlates strongly with HFA. It shows potential for population screening and monitoring visual field defects.

Translational Relevance

Perimouse assesses the visual field using saccade vectors without eye trackers, enhancing its accessibility via a web page.

Online Circular Contrast Perimetry via a Web-Application: Establishing a Normative Database for Central 10-Degree Perimetry

Purpose

To establish a normative database using a central 10-degree grid pattern for the online circular contrast perimetry (OCCP) application.

Participants

Fifty participants with mean age 65 ± 13 years were selected for this study. One eye from each participant that met inclusion criteria was randomly included in the cohort.

Methods

The web-application delivered online 52-loci perimetry in a central 10-degree pattern using circular flickering targets. These targets consist of concentric sinusoidal alternating contrast rings. Users were guided by the application to the correct viewing distance and head position using in-built blind spot localization and webcam monitoring. A spinning golden star was used as the fixation target and patients performed the test in a darkened room following standard automated perimetry (SAP).

Results

The reliability rates and global indices for OCCP were similar to SAP. OCCP mean sensitivity reduced with age at a similar rate to SAP. Mean sensitivity per loci of 10-degree OCCP was greater than SAP by 1.24 log units (95% CI 1.23 to 1.26) and obeyed a physiological hill of vision. Small differences existed in mean sensitivities between OCCP and SAP which increased with increasing spot eccentricity. Mean deviation (MD) displayed good agreement between the two tests.

Conclusion

Central 10-degree online circular contrast perimetry via a computer-based application has comparable perimetric results to standard automated perimetry in a normal cohort.

Participant Experience Using Novel Perimetry Tests to Monitor Glaucoma Progression

PRCIS

Participant surveys taken after using tablet-based and smart visual function analyzer (SVFA) perimetry tests suggest that patients may prefer novel perimetry tests over traditional visual field machines.

PURPOSE

Compare patient experience using the IMOvifa SVFA and the tablet-based Melbourne Rapid Fields visual field (VF) tests to the Humphrey Field 24-2 Swedish Interactive Threshold Algorithm Standard.

PATIENTS AND METHODS

Prospective observational cohort study on adult participants with diagnoses of glaucoma suspect, ocular hypertension, or glaucoma. Participants attended 2 study visits ~3 months apart. During the first visit, participants were trained to use the 2 novel perimeters, took 1 test on both new devices and the Humphrey Field Analyzer, then were surveyed. Participants received tablets and performed weekly tablet VF tests at home between study visits. At the final study visit, participants re-took the VF tests and completed the same surveys.

RESULTS

Eighty-one participants were surveyed twice. At the baseline survey, participants preferred the SVFA (71.7%) and tablet tests (69.2%) over the Humphrey VF. Most were willing to perform weekly monitoring at home on the SVFA (69.1%) and tablet (75.4%). Participants generally had a "very good" overall experience when testing on the SVFA (71.6%) and tablet (90.1%). At the final visit, fewer participants were willing to test on the tablet daily (23.5% to 9.9%; P = 0.02 for change) and more were willing to test monthly (18.5% to 33.3%; P = 0.03 for change).

CONCLUSION

Users reported a preference for novel VF devices. Overall participant experience using these devices was positive, supporting the feasibility of home monitoring of VFs from an experience perspective.

Remote Perimetry in a Virtual Reality Metaverse Environment for Out-of-Hospital Functional Eye Screening Compared Against the Gold Standard Humphrey Visual Fields Perimeter: Proof-of-Concept Pilot Study

BACKGROUND

The growing global burden of visual impairment necessitates better population eye screening for early detection of eye diseases. However, accessibility to testing is often limited and centralized at in-hospital settings. Furthermore, many eye screening programs were disrupted by the COVID-19 pandemic, presenting an urgent need for out-of-hospital solutions.

OBJECTIVE

This study investigates the performance of a novel remote perimetry application designed in a virtual reality metaverse environment to enable functional testing in community-based and primary care settings.

METHODS

This was a prospective observational study investigating the performance of a novel remote perimetry solution in comparison with the gold standard Humphrey visual field (HVF) perimeter. Subjects received a comprehensive ophthalmologic assessment, HVF perimetry, and remote perimetry testing. The primary outcome measure was the agreement in the classification of overall perimetry result normality by the HVF (Swedish interactive threshold algorithm-fast) and testing with the novel algorithm. Secondary outcome measures included concordance of individual testing points and perimetry topographic maps.

RESULTS

We recruited 10 subjects with an average age of 59.6 (range 28-81) years. Of these, 7 (70%) were male and 3 (30%) were female. The agreement in the classification of overall perimetry results was high (9/10, 90%). The pointwise concordance in the automated classification of individual test points was 83.3% (8.2%; range 75%-100%). In addition, there was good perimetry topographic concordance with the HVF in all subjects.

CONCLUSIONS

Remote perimetry in a metaverse environment had good concordance with gold standard perimetry using the HVF and could potentially avail functional eye screening in out-of-hospital settings.

Test-retest repeatability of the imo binocular random single-eye test and Humphrey monocular test in patients with glaucoma

PURPOSE

To evaluate the reproducibility of the imo binocular random single-eye test (BRSET) and Humphrey Field Analyzer (HFA) monocular test in patients with glaucoma.

STUDY DESIGN

Retrospective observational study.

METHODS

We measured the visual fields (VF) of patients with glaucoma using the BRSET and HFA. All tests were repeated two months later. Mean sensitivity (MS), mean deviation (MD), sensitivity at each test location, and reliability indices were compared between the test days. Wilcoxon signed-rank test, interclass correlation coefficient (ICC), correlation coefficients, and Bland-Altman plots were generated for analysis.

RESULTS

We analyzed the VFs of 46 patients with glaucoma. There were no test-retest differences for MS and MD, and ICCs were > 0.9 for MS and MD in both perimeters. Inter-test correlations for MS and MD were high. The limits of agreement (LoAs) (lower, upper limit) between test days for MS were (- 3.4, 4.0) for BRSET and (-3.3, 3.0) for HFA. The LoA for MD was (- 3.3, 3.8) for BRSET and (- 3.2, 2.9) for HFA. Sensitivity at each testing location was more variable between testing days for BRSET than for HFA. For reliability indices, LoAs between testing days were wider for BRSET than for HFA.

CONCLUSION

The imo BRSET showed similar reproducibility to HFA in MS and MD. However, sensitivity at each test location varied more for BRSET than for HFA. Further studies are needed to verify the reproducibility of the imo BRSET.

Comparison of Perimetric Outcomes from a Tablet Perimeter, Smart Visual Function Analyzer, and Humphrey Field Analyzer

PURPOSE

The tablet-based Melbourne Rapid Fields (MRF) visual field (VF) test and the IMOvifa Smart Visual Function Analyzer (SVFA) are portable perimeters that may allow for at-home monitoring and more frequent testing. We compared tablet and SVFA results with outputs from the Humphrey Field Analyzer (HFA) 24-2 Swedish Interactive Threshold Algorithm Standard program.

DESIGN

Observational cross-sectional study.

SUBJECTS

Adult participants with a diagnosis of glaucoma, suspected glaucoma, or ocular hypertension seen in the Massachusetts Eye and Ear glaucoma clinic were enrolled. All participants were reliable and experienced HFA testers.

METHODS

Participants were tested with the SVFA and HFA. The study staff also trained participants on the MRF tablet with instructions to take weekly tests at home for 3 months. Visual field results from the 3 devices were compared.

MAIN OUTCOME MEASURES

Mean deviation (MD), pattern standard deviation (PSD), reliability parameters, and point sensitivity.

RESULTS

Overall, 79 participants (133 eyes) with a mean age of 61 ± 13 years (range, 26-79 years) were included; 59% of the participants were female, and the mean HFA MD was -2.7 ± 3.9 dB. The global indices of MD and PSD did not significantly vary between HFA and the 2 novel devices, except that the tablet VF reported a 0.6 dB higher PSD compared with HFA. However, tablet and SVFA sensitivities significantly differed from those of the HFA at 36 and 39 locations, respectively, out of 52 locations. Relative to HFA, the tablet overestimated light sensitivity in the nasal field while underestimating the temporal field. The SVFA generally underestimated light sensitivity, but its results were more similar to HFA results compared with the tablet.

CONCLUSIONS

Although average MD values from the 2 novel devices suggest that they provide similar results to the HFA, point-by-point comparisons highlight notable deviations. Differences in specific point sensitivity values were significant, especially between the tablet and the other 2 devices. These differences may in part be explained by differences in the devices' normative databases as well as how MD is calculated. However, the tablet had substantial differences based on location, indicating that the tablet design itself may be responsible for differences in local sensitivities.

FINANCIAL DISCLOSURE(S)

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

Eye Tracking in Optometry: A Systematic Review

This systematic review examines the use of eye-tracking devices in optometry, describing their main characteristics, areas of application and metrics used. Using the PRISMA method, a systematic search was performed of three databases. The search strategy identified 141 reports relevant to this topic, indicating the exponential growth over the past ten years of the use of eye trackers in optometry. Eye-tracking technology was applied in at least 12 areas of the field of optometry and rehabilitation, the main ones being optometric device technology, and the assessment, treatment, and analysis of ocular disorders. The main devices reported on were infrared light-based and had an image capture frequency of 60 Hz to 2000 Hz. The main metrics mentioned were fixations, saccadic movements, smooth pursuit, microsaccades, and pupil variables. Study quality was sometimes limited in that incomplete information was provided regarding the devices used, the study design, the methods used, participants' visual function and statistical treatment of data. While there is still a need for more research in this area, eye-tracking devices should be more actively incorporated as a useful tool with both clinical and research applications. This review highlights the robustness this technology offers to obtain objective information about a person's vision in terms of optometry and visual function, with implications for improving visual health services and our understanding of the vision process.

Stimulus contrast, pursuit mode, and age strongly influence tracking performance on a continuous visual tracking task

Human observers tend to naturally track moving stimuli. This tendency may be exploited towards an intuitive means of screening visual function as an impairment induced reduction in stimulus visibility will decrease tracking performance. Yet, to be able to detect subtle impairments, stimulus contrast is critical. If too high, the decrease in performance may remain undetected. Therefore, for this approach to become reliable and sensitive, we need a detailed understanding of how age, stimulus contrast, and the type of stimulus movement affect continuous tracking performance. To do so, we evaluated how well twenty younger and twenty older participants tracked a semi-randomly moving stimulus (Goldmann size III, 0.43 degrees of visual angle), presented at five contrast levels (5%-10%-20%-40%-80%). The stimulus could move smoothly only (smooth pursuit mode) or in alternation with displacements (saccadic pursuit mode). Additionally, we assessed static foveal and peripheral contrast thresholds. For all participants, tracking performance improved with increasing contrast in both pursuit modes. To reach threshold performance levels, older participants required about twice as much contrast (20% vs. 10% and 40% vs. 20% in smooth and saccadic modes respectively). Saccadic pursuit detection thresholds correlated significantly with static peripheral contrast thresholds (rho = 0.64). Smooth pursuit detection thresholds were uncorrelated with static foveal contrast thresholds (rho = 0.29). We conclude that continuous visual stimulus tracking is strongly affected by stimulus contrast, pursuit mode, and age. This provides essential insights that can be applied towards new and intuitive approaches of screening visual function.

Online Circular Contrast Perimetry: A Comparison to Standard Automated Perimetry

PURPOSE

The aim was to validate and compare the diagnostic accuracy of a novel 24-degree, 52-loci online circular contrast perimetry (OCCP) application to standard automated perimetry (SAP).

DESIGN

Prospective cohort study.

METHODS

Two hundred and twenty participants (125 normal controls, 95 open angle glaucoma patients) were included. Agreement, correlation, sensitivity, specificity, and area under receiver operating curves (AUC) were compared for parameters of OCCP, SAP, and optical coherence tomography (OCT) for the retinal nerve fiber layer and macular ganglion cell complex inner plexiform layer.

RESULTS

Pointwise sensitivity for OCCP was greater than SAP by 1.02 log units (95% CI: 0.95-1.08); 95% limits of agreement 0.860 to 1.17. Correlation and agreement for global indices and regional zones between OCCP and SAP were strong. OCCP mean deviation (MD) AUC was 0.885±0.08, similar to other instruments' parameters with the highest AUC: SAP MD (0.851±0.08), OCT retinal nerve fiber layer inferior thickness (0.908±0.07), OCT ganglion cell complex inner plexiform layer inferior thickness (0.849±0.08), P>0.05. At best cutoff, OCCP MD sensitivity/specificity were comparable to SAP MD (90/74 vs 94/65%).

CONCLUSIONS

OCCP demonstrates similar perimetric sensitivities to SAP and similar AUC to SAP and OCT in distinguishing glaucoma patients from controls. OCCP holds promise as a glaucoma surveillance and screening tool, with the potential to be utilized for in-clinic and at-home perimetry and expand community testing.

A systematic review of the current availability of mobile applications in eyecare practices

BACKGROUND

There is an increasing shift towards non-communicable eye diseases (NCEDs) because of a demographic transition. Incorporation of telemedicine into everyday clinical practice is becoming increasingly popular. We sought to carry out a systematic review to look at which applications on portable devices are available for use in eyecare practices for patients with NCEDs, specifically refractive error, diabetic retinopathy, age-related macular degeneration (AMD) and glaucoma.

METHODS

Pubmed, EMBASE, Medline, PsychInfo databases were systematically searched using keywords and MeSH terms. Eligible articles included peer-reviewed, original full text articles evaluating apps for use on portable devices aimed at patients with NCEDs.

RESULTS

The initial search yielded 100 studies. Nine studies met the inclusion criteria, and an additional eight studies were identified through reference screening. Of the included studies, 29.4%% (n = 5) evaluated applications aimed for use to identify refractive errors, 35.3% (n = 6) aimed at patients with glaucoma, 23.5% (n = 4) for use by patients with AMD, 11.7% (n = 2) for the non-specific monitoring of visual acuity/fields. 76.5% (n = 13) of the studies showed that the application evaluated was an effective and reliable tool compared to clinical standards.

CONCLUSIONS

Portable device applications in patients with NCED have been shown to be effective. The use of these apps for patients is limited to either diagnostic or monitoring use. There is scope for apps which encompass other aspects of patient care that have been used in other specialties that may be applied to ophthalmic patients, including those with an educational aim which have a role in increasing compliance.

Circular Contrast Perimetry via a Web Application: A Patient Appraisal and Comparison to Standard Automated Perimetry

Purpose

Design

Subjects

Methods

Main Outcome Measures

Results

Conclusions

Test Reliability and Compliance to a Twelve-Month Visual Field Telemedicine Study in Glaucoma Patients

Background: Our primary aim is to quantify test reliability and compliance of glaucoma patients to a weekly visual field telemedicine (VFTM) schedule. A secondary aim is to determine concordance of the VFTM results to in-clinic outcomes. Methods: Participants with stable glaucoma in one eye were recruited for a 12 month VFTM trial using the Melbourne Rapid Fields (MRF-home, MRFh) iPad application. Participants attended routine 6 month clinical reviews and were tasked with weekly home monitoring with the MRFh over this period. We determined compliance to weekly VFTM (7 + 1 days) and test reliability (false positives (FPs) and fixation loss (FL) <33%). A secondary aim considered concordance to in-clinic measures of visual field (MRF-clinic (MRFc) and the Humphrey Field Analyzer (HFA)) in active participants (≥10 home examinations and 5 reliable HFA examinations). The linear trend in the MRFh mean deviation (MD) was compared to the HFA guided progression analysis (GPA) using Bland−Altman methods. Data are shown as the mean ± standard deviation. Results: Forty-seven participants with a mean age of 64 ± 14.6 years were recruited for the trial. The VFTM uptake was 85% and compliance to weekly home monitoring was 75% in the presence of weekly text reminders in the analysed group (n = 20). The analysed group was composed of test subjects with five reliable in-clinic HFA examinations (GPA analysis available) and who submitted a minimum of 10 MRFh examinations from home. Of the 757 home examinations returned, approximately two-thirds were reliable, which was significantly lower than the test reliability of the HFA in-clinic (MRFh: 65% vs. HFA: 85%, p < 0.001). The HFA-GPA analysis gave little bias from the MRFh slope (bias: 0.05 dB/yr, p > 0.05). Two eyes were found to have clinical progression during the 12 month period, and both were detected by VFTM. Conclusions: VFTM over 12 months returned good compliance (75%) to weekly testing with good concordance to in-clinic assays. VFTM is a viable option for monitoring patients with glaucoma for visual field progression in between clinical visits.

Spotlight on iPad Visual Field Tests Efficacy

Tablet based perimetry has the potential to be used as a low-cost, portable method for glaucoma screening. With the advent of tablets with large dynamic luminance range and high spatial resolution, perimetry applications can test visual field locations within the central 30 degrees, just like bowl perimetry. Tablet perimetry has garnered interest in this COVID era as it can be promptly done in the waiting room or even from the comfort of home. The current review focuses on evaluating glaucoma detection sensitivities, diagnostic abilities and correlation of each parameter and examination time of the iPad based perimetry applications with those of HFA.

Remote Video Monitoring of Simultaneous Visual Field Testing

PRCIS

In this prospective interventional case series that included 474 patients, there were no significant differences in visual field (VF) parameters between fields from patients tested one-at-a-time and simultaneously, except for fixation losses.

PURPOSE

To test for differences in reliability and performance parameters of patients taking VF tests while using a remote patient monitoring system to supervise 1 or 2 test sessions simultaneously.

METHODS

In a prospective interventional case series, 861 eyes of 474 consecutive patients undergoing automated perimetry during a 6-month period were monitored during the test using an audio/video-enabled remote monitoring system. Two patients were simultaneously tested (simultaneous test) by a single technician if they were ready for testing at the same time. Patients were otherwise tested individually (single test). Performance and reliability parameters including false negatives, false positives, fixation losses, mean deviation, pattern standard deviation, VF index, and test duration were compared between patients undergoing simultaneous tests and single tests. Patients undergoing remotely monitored testing, for whom a prior VF could be found, had performance and reliability parameters compared with those prior tests. VFs were analyzed separately for 2 test strategies: SITA Standard 24-2 and SITA Faster 24-2C.

RESULTS

No significant parameter differences were observed among SITA Standard 24-2 VFs between single and simultaneous tests, except for fixation losses (single: 16.8±19.7%, simultaneous: 22.5±25.0%, P=0.01). Similarly, there were no significant differences observed among SITA Faster 24-2C tests. Paired analyses comparing remotely monitored VFs with prior traditionally monitored VFs showed no significant differences for any parameters, except for fewer fixation losses with remote monitoring (traditional: 23.6±27.5%, remote 17.7±20.8%, P=0.003).

CONCLUSIONS

Remote patient monitoring of VF testing enabled technicians to supervise testing of 2 patients simultaneously with preserved performance and reliability.

Home-Based Perimetry for Glaucoma: Where Are We Now?

PURPOSE

To systematically summarize the current literature on home-based perimeters for glaucoma.

METHODS

A systematic review was conducted in accordance with the PRISMA-DTA checklist. Studies reporting portable perimeters designed for home use were retrieved from electronic databases and handsearching of reference lists of relevant publications. Studies reporting diagnostic accuracy data were evaluated with the QUADAS-2 tool and using standard automated perimetry as the reference standard. Other aspects of the technology such as detection of disease progression and patient acceptability were also included. Data were reported in a narrative and tabular format.

RESULTS

Of 18 included studies, 10 evaluated tablet-based perimeters, 4 evaluated web-based perimeters, and 4 evaluated head-mounted displays. Most studies used a clinic or laboratory setting. All studies reporting diagnostic accuracy data had high risk of bias in at least one domain. Across studies, sensitivity ranged from 54% in detecting mild to 91% in detecting moderate/severe glaucoma patients from controls, while specificity was between 50% and 100% for any form of glaucoma. The reported acceptability was high but had high risk of bias.

CONCLUSION

Several promising technologies designed for home-based perimetry have been reported. Current studies used a controlled setting in highly selected populations. There is uncertainty on the performance and value of home-based perimetry for glaucoma. Additional efforts are required to elucidate the ability of the home-based perimeters to detect glaucoma and disease progression in real life situations.

Developing a Screening Tool for Areas of Abnormal Central Vision Using Visual Stimuli With Natural Scene Statistics

Purpose

Previous studies show that some visual field (VF) defects are detectable from visual search behavior; for example, when watching video. Here, we developed and tested a VF testing approach that measures the number of fixations to find targets on a background with spatial frequency content similar to natural scenes.

Methods

Twenty-one older controls and 20 people with glaucoma participated. Participants searched for a Gabor (6 c/°) that appeared in one of 25 possible locations within a 15° (visual angle) 1/f noise background (RMS contrast: 0.20). Procedure performance was assessed by calculating sensitivity and specificity for different combinations of control performance limits (p = 95%, 98%, 99%), number of target locations with fixations outside control performance limits (k = 0 to 25) and number of repeated target presentations (n = 1 to 20).

Results

Controls made a median of two to three fixations (twenty-fifth to seventy-fifth percentile: two to four) to locate the target depending on location. A VF was flagged “abnormal” when the number of fixations was greater than the p = 99% for k = 3 or more locations with n = 2 repeated presentations, giving 85% sensitivity and 95.2% specificity. The median test time for controls was 85.71 (twenty-fifth to seventy-fifth percentile: 66.49–113.53) seconds.

Conclusion

Our prototype test demonstrated effective and efficient screening of abnormal areas in central vision.

Translational Relevance

Visual search behavior can be used to detect central vision loss and may produce results that relate well to performance in natural visual environments.

Serafini R, Lakhtakia S, Valliani AA, Warburton AJ, Patel A, Zhou D, Sklar B, Chelnis J, Elahi E. Portable hardware & software technologies for addressing ophthalmic health disparities: A systematic review

Vision impairment continues to be a major global problem, as the WHO estimates 2.2 billion people struggling with vision loss or blindness. One billion of these cases, however, can be prevented by expanding diagnostic capabilities. Direct global healthcare costs associated with these conditions totaled $255 billion in 2010, with a rapid upward projection to $294 billion in 2020. Accordingly, WHO proposed 2030 targets to enhance integration and patient-centered vision care by expanding refractive error and cataract worldwide coverage. Due to the limitations in cost and portability of adapted vision screening models, there is a clear need for new, more accessible vision testing tools in vision care. This comparative, systematic review highlights the need for new ophthalmic equipment and approaches while looking at existing and emerging technologies that could expand the capacity for disease identification and access to diagnostic tools. Specifically, the review focuses on portable hardware- and software-centered strategies that can be deployed in remote locations for detection of ophthalmic conditions and refractive error. Advancements in portable hardware, automated software screening tools, and big data-centric analytics, including machine learning, may provide an avenue for improving ophthalmic healthcare.

Patients Prefer a Virtual Reality Approach Over a Similarly Performing Screen-Based Approach for Continuous Oculomotor-Based Screening of Glaucomatous and Neuro-Ophthalmological Visual Field Defects

Standard automated perimetry (SAP) is the gold standard for evaluating the presence of visual field defects (VFDs). Nevertheless, it has requirements such as prolonged attention, stable fixation, and a need for a motor response that limit application in various patient groups. Therefore, a novel approach using eye movements (EMs) - as a complementary technique to SAP - was developed and tested in clinical settings by our group. However, the original method uses a screen-based eye-tracker which still requires participants to keep their chin and head stable. Virtual reality (VR) has shown much promise in ophthalmic diagnostics - especially in terms of freedom of head movement and precise control over experimental settings, besides being portable. In this study, we set out to see if patients can be screened for VFDs based on their EM in a VR-based framework and if they are comparable to the screen-based eyetracker. Moreover, we wanted to know if this framework can provide an effective and enjoyable user experience (UX) compared to our previous approach and the conventional SAP. Therefore, we first modified our method and implemented it on a VR head-mounted device with built-in eye tracking. Subsequently, 15 controls naïve to SAP, 15 patients with a neuro-ophthalmological disorder, and 15 glaucoma patients performed three tasks in a counterbalanced manner: (1) a visual tracking task on the VR headset while their EM was recorded, (2) the preceding tracking task but on a conventional screen-based eye tracker, and (3) SAP. We then quantified the spatio-temporal properties (STP) of the EM of each group using a cross-correlogram analysis. Finally, we evaluated the human-computer interaction (HCI) aspects of the participants in the three methods using a user-experience questionnaire. We find that: (1) the VR framework can distinguish the participants according to their oculomotor characteristics; (2) the STP of the VR framework are similar to those from the screen-based eye tracker; and (3) participants from all the groups found the VR-screening test to be the most attractive. Thus, we conclude that the EM-based approach implemented in VR can be a user-friendly and portable companion to complement existing perimetric techniques in ophthalmic clinics.

Virtual Reality-Based and Conventional Visual Field Examination Comparison in Healthy and Glaucoma Patients

Purpose

Clinically evaluate the noninferiority of a custom virtual reality (VR) perimetry system when compared to a clinically and routinely used perimeter on both healthy subjects and glaucoma patients.

Methods

We use a custom-designed VR perimetry system tailored for visual field testing. The system uses Oculus Quest VR headset (Facebook Technologies, LLC, Bern, Switzerland), that includes a clicker for participant response feedback. A prospective, single center, study was conducted at the Department of Ophthalmology of the Bern University Hospital (Bern, Switzerland) for 12 months. Of the 114 participants recruited 70 subjects (36 healthy and 34 glaucoma patients with early to moderate visual field loss) were included in the study. Participants underwent perimetry tests on an Octopus 900 (Haag-Streit, Köniz, Switzerland) as well as on the custom VR perimeter. In both cases, standard dynamic strategy (DS) was used in conjunction with the G testing pattern. Collected visual fields (VFs) from both devices were then analyzed and compared.

Results

High mean defect (MD) correlations between the two systems (Spearman, ρ ≥ 0.75) were obtained. The VR system was found to slightly underestimate VF defects in glaucoma subjects (1.4 dB). No significant bias was found with respect to eccentricity or subject age. On average, a similar number of stimuli presentations per VF was necessary when measuring glaucoma patients and healthy subjects.

Conclusions

This study demonstrates that a clinically used perimeter and the proposed VR perimetry system have comparable performances with respect to a number of perimetry parameters in healthy and glaucoma patients with early to moderate visual field loss.

Translational Relevance

This suggests that VR perimeters have the potential to assess VFs with high enough confidence, whereby alleviating challenges in current perimetry practices by providing a portable and more accessible visual field test.

Acceptance of a Smartphone-Based Visual Field Screening Platform for Glaucoma: Pre-Post Study

Background

Glaucoma, the silent thief of sight, is a major cause of blindness worldwide. It is a burden for people in low-income countries, specifically countries where glaucoma-induced blindness accounts for 15% of the total incidence of blindness. More than half the people living with glaucoma in low-income countries are unaware of the disease until it progresses to an advanced stage, resulting in permanent visual impairment.

Objective

This study aims to evaluate the acceptability of the Glaucoma Easy Screener (GES), a low-cost and portable visual field screening platform comprising a smartphone, a stereoscopic virtual reality headset, and a gaming joystick.

Methods

A mixed methods study that included 24 eye care professionals from 4 hospitals in Southwest Ethiopia was conducted to evaluate the acceptability of GES. A pre-post design was used to collect perspectives before and after using the GES by using questionnaires and semistructured interviews. A Wilcoxon signed-rank test was used to determine the significance of any change in the scores of the questionnaire items (two-tailed, 95% CI; α=.05). The questionnaire and interview questions were guided by the Unified Theory of Acceptance and Use of Technology.

Results

Positive results were obtained both before and after use, suggesting the acceptance of mobile health solutions for conducting glaucoma screening by using a low-cost headset with a smartphone and a game controller. There was a significant increase (two-tailed, 95% CI; α=.05) in the average scores of 86% (19/22) of postuse questionnaire items compared with those of preuse questionnaire items. Ophthalmic professionals perceived GES as easy to use and as a tool that enabled the conduct of glaucoma screening tests, especially during outreach to rural areas. However, positive evaluations are contingent on the accuracy of the tool. Moreover, ophthalmologists voiced the need to limit the tool to screening only (ie, not for making diagnoses).

Conclusions

This study supports the feasibility of using a mobile device in combination with a low-cost virtual reality headset and classic controller for glaucoma screening in rural areas. GES has the potential to reduce the burden of irreversible blindness caused by glaucoma. However, further assessment of its sensitivity and specificity is required.

Multicenter Comparison of the Toronto Portable Perimeter with the Humphrey Field Analyzer: A Pilot Study

PURPOSE

To evaluate the agreement between glaucomatous 24-2 visual field (VF) testing performed with the Toronto Portable Perimeter (TPP; VEM Medical Technologies) and the Humphrey Field Analyzer (HFA; Carl Zeiss Meditec).

DESIGN

Multicenter prospective cohort analysis.

PARTICIPANTS

Patients with suspected or confirmed glaucoma treated at Prism Eye Institute (Oakville, Canada), York Finch Eye Associates (North York, Canada), or the Ontario Mobile Medical Eye Care Unit (Cochrane, Canada) between March 2019 and March 2020.

METHODS

Patients underwent consecutive VF tests on the same eye using the HFA Swedish Interactive Threshold Algorithm Standard 24-2 test and TPP Standard 24-2 test in randomized order. Bland-Altman analysis and paired t tests were used to compare VF results obtained by the TPP and the HFA. Participants completed a 5-question validated questionnaire after completing both testing methods.

MAIN OUTCOME MEASURES

Mean difference and degree of agreement in mean deviation (MD), pattern standard deviation (PSD), visual field index (VFI), and test duration between VF modalities.

RESULTS

One hundred fifty eyes from 91 patients were included in analysis. Average MD of the overall cohort using HFA and TPP VF testing was -4.32 ± 5.47 dB and -4.53 ± 5.22 dB, respectively (P = 0.74). Bland-Altman analysis showed good agreement between HFA and TPP tests. The mean differences (95% limits of agreement) between HFA and TPP for MD, PSD, VFI, and test duration were 0.21 dB (-4.25 to 4.67 dB), -0.13 dB (-3.72 to 3.47 dB), 0.66% (-10.94% to 12.26%), and 0.65 seconds (-97.51 to 98.81 seconds), respectively. No statistically significant mean difference was found between HFA and TPP tests for MD, PSD, VFI, or test duration. Mean deviation (R² = 0.830) and VFI (R² = 0.866) were correlated strongly with both modalities. Questionnaire results demonstrated that patients significantly preferred the TPP over the HFA for VF testing (P < 0.001).

CONCLUSIONS

Mean deviation, PSD, and VFI outcomes measured by the TPP were statistically similar to corresponding parameters obtained with the HFA. Test time duration did not differ significantly between the TPP and HFA, and patients significantly preferred the TPP to the HFA examination experience. These pilot results suggest that the TPP may offer an accessible alternative to HFA VF testing.

Computational Methods for Continuous Eye-Tracking Perimetry Based on Spatio-Temporal Integration and a Deep Recurrent Neural Network

The measurement of retinal sensitivity at different visual field locations-perimetry-is a fundamental procedure in ophthalmology. The most common technique for this scope, the Standard Automated Perimetry, suffers from several issues that make it less suitable to test specific clinical populations: it can be tedious, it requires motor manual feedback, and requires from the patient high levels of compliance. Previous studies attempted to create user-friendlier alternatives to Standard Automated Perimetry by employing eye movements reaction times as a substitute for manual responses while keeping the fixed-grid stimuli presentation typical of Standard Automated Perimetry. This approach, however, does not take advantage of the high spatial and temporal resolution enabled by the use of eye-tracking. In this study, we introduce a novel eye-tracking method to perform high-resolution perimetry. This method is based on the continuous gaze-tracking of a stimulus moving along a pseudo-random walk interleaved with saccadic jumps. We then propose two computational methods to obtain visual field maps from the continuous gaze-tracking data: the first is based on the spatio-temporal integration of ocular positional deviations using the threshold free cluster enhancement (TFCE) algorithm; the second is based on using simulated visual field defects to train a deep recurrent neural network (RNN). These two methods have complementary qualities: the TFCE is neurophysiologically plausible and its output significantly correlates with Standard Automated Perimetry performed with the Humphrey Field Analyzer, while the RNN accuracy significantly outperformed the TFCE in reconstructing the simulated scotomas but did not translate as well to the clinical data from glaucoma patients. While both of these methods require further optimization, they show the potential for a more patient-friendly alternative to Standard Automated Perimetry.

Acceptability of a home-based visual field test (Eyecatcher) for glaucoma home monitoring: a qualitative study of patients' views and experiences

OBJECTIVES

To explore the acceptability of home visual field (VF) testing using Eyecatcher among people with glaucoma participating in a 6-month home monitoring pilot study.

DESIGN

Qualitative study using face-to-face semistructured interviews. Transcripts were analysed using thematic analysis.

SETTING

Participants were recruited in the UK through an advertisement in the International Glaucoma Association (now Glaucoma UK) newsletter.

PARTICIPANTS

Twenty adults (10 women; median age: 71 years) with a diagnosis of glaucoma were recruited (including open angle and normal tension glaucoma; mean deviation=2.5 to -29.9 dB).

RESULTS

All participants could successfully perform VF testing at home. Interview data were coded into four overarching themes regarding experiences of undertaking VF home monitoring and attitudes towards its wider implementation in healthcare: (1) comparisons between Eyecatcher and Humphrey Field Analyser (HFA); (2) capability using Eyecatcher; (3) practicalities for effective wider scale implementation; (4) motivations for home monitoring.

CONCLUSIONS

Participants identified a broad range of benefits to VF home monitoring and discussed areas for service improvement. Eyecatcher was compared positively with conventional VF testing using HFA. Home monitoring may be acceptable to at least a subset of people with glaucoma.

Glaucoma Home Monitoring Using a Tablet-Based Visual Field Test (Eyecatcher): An Assessment of Accuracy and Adherence Over 6 Months

Purpose

To assess accuracy and adherence of visual field (VF) home monitoring in a pilot sample of patients with glaucoma.

Design

Prospective longitudinal feasibility and reliability study.

Methods

Twenty adults (median 71 years) with an established diagnosis of glaucoma were issued a tablet perimeter (Eyecatcher) and were asked to perform 1 VF home assessment per eye, per month, for 6 months (12 tests total). Before and after home monitoring, 2 VF assessments were performed in clinic using standard automated perimetry (4 tests total, per eye).

Results

All 20 participants could perform monthly home monitoring, though 1 participant stopped after 4 months (adherence: 98% of tests). There was good concordance between VFs measured at home and in the clinic (r = 0.94, P < .001). In 21 of 236 tests (9%), mean deviation deviated by more than ±3 dB from the median. Many of these anomalous tests could be identified by applying machine learning techniques to recordings from the tablets' front-facing camera (area under the receiver operating characteristic curve = 0.78). Adding home-monitoring data to 2 standard automated perimetry tests made 6 months apart reduced measurement error (between-test measurement variability) in 97% of eyes, with mean absolute error more than halving in 90% of eyes. Median test duration was 4.5 minutes (quartiles: 3.9-5.2 minutes). Substantial variations in ambient illumination had no observable effect on VF measurements (r = 0.07, P = .320).

Conclusions

Home monitoring of VFs is viable for some patients and may provide clinically useful data.

Uptake, Persistence, and Performance of Weekly Home Monitoring of Visual Field in a Large Cohort of Patients With Glaucoma

PURPOSE

This study examines the short-term uptake, compliance, and performance of a tablet device used for home monitoring of visual field (VF-Home) by glaucoma patients.

DESIGN

Single-center, observational, longitudinal, compliance study.

METHODS

Participants who were glaucoma suspects or had stable glaucoma in at least one eye were recruited during a regular clinic review. Baseline in-clinic visual field (VF) was recorded with the Humphrey Field Analyser (HFA, SITA standard) and repeated at 6 months. Participants were tasked with performing 6 VF examinations from home, at weekly intervals, using a loaned iPad tablet. Uptake was defined as returning at least 1 test from home. Reliability and global indices from VF-Home were compared to in-clinic outcomes. Data are shown as either mean ± [standard deviation] or median [quartile 1-3 range], and group comparisons were achieved with bootstrap.

RESULTS

We recruited 186 eyes of 101 participants. VF-Home uptake was excellent, with 88% of participants successfully completing ≥1 home examination and 69% completing all 6 examinations. The median duration between tests was 7.0 [7.0-8.0] days. Barriers to uptake and compliance involved information technology (IT) logistical reasons, lack of motivation, or competing life demands. VF-Home gave greater fixation loss but a similar level of False Positives (FP) as the HFA. A high correlation was found for the mean defect between in-clinic and at-home outcomes (R = 0.85).

CONCLUSIONS

VF-Home can return a high level of short-term compliance and results comparable to those found by in-clinic testing. IT logistical reasons and lack of motivation are barriers to uptake and compliance.

Advances in perimetry for glaucoma

PURPOSE OF REVIEW

Perimetry remains important for the diagnosis and management of glaucoma despite advances in imaging technology. The purpose of this review is to describe advances in the acquisition and analysis of visual field data and highlight novel techniques for performing perimetry.

RECENT FINDINGS

Studies have focused on improving the detection of patients at highest risk of severe vision loss and the development of innovative testing strategies that allow for more frequent testing. Artificial intelligence has been utilized in research settings to improve detection and characterization of glaucomatous field damage. Furthermore, tablet-based strategies and virtual reality headsets show promise for glaucoma screening and remote monitoring of patients with glaucoma.

SUMMARY

New testing strategies and research findings have improved our ability to identify patients with both paracentral and mid-peripheral visual field progression. New strategies have the potential to make visual field testing more efficient, reliable and accessible for patients with glaucoma.

A case control study examining the feasibility of using eye tracking perimetry to differentiate patients with glaucoma from healthy controls

To explore the feasibility of using Saccadic Vector Optokinetic Perimetry (SVOP) to differentiate glaucomatous and healthy eyes. A prospective case-control study was performed using a convenience sample recruited from a single university glaucoma clinic and a group of healthy controls. SVOP and standard automated perimetry (SAP) was performed with testing order randomised. The reference standard was a diagnosis of glaucoma based a comprehensive ophthalmic examination and abnormality on standard automated perimetry (SAP). The index test was SVOP. 31 patients with glaucoma and 24 healthy subjects were included. Mean SAP mean deviation (MD) in those with glaucoma was - 8.7 ± 7.4 dB, with mean SAP and SVOP sensitivities of 23.3 ± 0.9 dB and 22.1 ± 4.3 dB respectively. Participants with glaucoma were significantly older. On average, SAP sensitivity was 1.2 ± 1.4 dB higher than SVOP (95% limits of agreement = - 1.6 to 4.0 dB). SVOP sensitivity had good ability to differentiate healthy and glaucomatous eyes with a 95% CI for area under the curve (AUC) of 0.84 to 0.96, similar to the performance of SAP sensitivity (95% CI 0.86 to 0.97, P = 0.60). For 80% specificity, SVOP had a 95% CI sensitivity of 75.7% to 94.8% compared to 77.8% to 96.0% for SAP. SVOP took considerably longer to perform (514 ± 54 s compared to 267 ± 76 s for SAP). Eye tracking perimetry may be useful for detection of glaucoma but further studies are needed to evaluate SVOP within its intended sphere of use, using an appropriate design and independent reference standard.

Development of an Age-corrected Normative Database for Saccadic Vector Optokinetic Perimetry (SVOP)

PRECIS

Normal age-corrected threshold sensitivity values were determined for a new eye tracking perimeter and compared with standard automated perimetry (SAP).

PURPOSE

The purpose of this study was to determine threshold visual field sensitivities in normal subjects performing saccadic vector optokinetic perimetry (SVOP), a new eye tracking perimeter.

PATIENTS AND METHODS

A total of 113 healthy participants performed SVOP and SAP in both eyes with the order of testing randomized. The relationship between SAP and SVOP sensitivity was examined using Bland-Altman plots and 95% limits of agreement. The relationship between sensitivity and age was examined by pointwise linear regression and age-corrected normal threshold sensitivities were calculated.

RESULTS

After excluding unreliable tests, 97 participants with a mean age of 65.9±10.1 years were included. Average SAP mean deviation was -0.87±1.56 dB, SAP sensitivity was 29.20±1.68 dB and SVOP sensitivity was 32.18±1.96 dB. SVOP had a longer test duration (431±110 compared with 307±42 seconds for SAP, P<0.001). On average, the mean sensitivity obtained using SVOP was 2.98 dB higher than average SAP sensitivity, with 95% limits of agreement of -0.11 to 6.15 dB. For each decade older, SAP sensitivity decreased by 0.93 dB (95% confidence interval: 1.21 to 0.64) and SVOP sensitivity decreased by 1.15 dB (95% confidence interval: 1.47 to 0.84).

CONCLUSIONS

The results provide age-corrected normative values for threshold sensitivities from SVOP. Overall, SVOP provided a similar shaped hill of vision as SAP however threshold sensitivities were higher, meaning results are not interchangeable.

A critical review: Psychophysical assessments of diabetic retinopathy

Diabetic retinal disease remains a leading cause of vision loss despite currently available screening methods, ocular treatments, and efforts to control metabolic dysfunction. It is now understood that diabetes damages the entire retina and the cellular components of the neurovascular unit. Multiple studies have demonstrated impairment of various aspects of retinal function across the spectrum of retinopathy severity. Here we review these tests, the principles underlying their use, clinical data from multiple publications, the strengths and limitations of the studies, and prospects for their application to understand the pathophysiology of diabetic retinal disease and monitor its response to therapy. We focus on visual acuity, contrast sensitivity, color vision, visual field, and dark adaptation and their use to understand the pathophysiology of diabetic retinopathy and as potential endpoints for clinical trials.

Using an open-source tablet perimeter (Eyecatcher) as a rapid triage measure for glaucoma clinic waiting areas

Background

Glaucoma services are under unprecedented strain. The UK Healthcare Safety Investigation Branch recently called for new ways to identify glaucoma patients most at risk of developing sight loss, and of filtering-out false-positive referrals. Here, we evaluate the feasibility of one such technology, Eyecatcher: a free, tablet-based ‘triage’ perimeter, designed to be used unsupervised in clinic waiting areas. Eyecatcher does not require a button or headrest: patients are simply required to look at fixed-luminance dots as they appear.

Methods

Seventy-seven people were tested twice using Eyecatcher (one eye only) while waiting for a routine appointment in a UK glaucoma clinic. The sample included individuals with an established diagnosis of glaucoma, and false-positive new referrals (no visual field or optic nerve abnormalities). No attempts were made to control the testing environment. Patients wore their own glasses and received minimal task instruction.

Results

Eyecatcher was fast (median: 2.5 min), produced results in good agreement with standard automated perimetry (SAP), and was rated as more enjoyable, less tiring and easier to perform than SAP (all p<0.001). It exhibited good separation (area under receiver operating characteristic=0.97) between eyes with advanced field loss (mean deviation (MD) < −6 dB) and those within normal limits (MD > −2 dB). And it was able to flag two thirds of false-positive referrals as functionally normal. However, eight people (10%) failed to complete the test twice, and reasons for this limitation are discussed.

Conclusions

Tablet-based eye-movement perimetry could potentially provide a pragmatic way of triaging busy glaucoma clinics (ie, flagging high-risk patients and possible false-positive referrals).

The Human Touch: Using a Webcam to Autonomously Monitor Compliance During Visual Field Assessments

Purpose

To explore the feasibility of using various easy-to-obtain biomarkers to monitor non-compliance (measurement error) during visual field assessments.

Methods

Forty-two healthy adults (42 eyes) and seven glaucoma patients (14 eyes) underwent two same-day visual field assessments. An ordinary webcam was used to compute seven potential biomarkers of task compliance, based primarily on eye gaze, head pose, and facial expression. We quantified the association between each biomarker and measurement error, as defined by (1) test–retest differences in overall test scores (mean sensitivity), and (2) failures to respond to visible stimuli on individual trials (stimuli −3 dB or more brighter than threshold).

Results

In healthy eyes, three of the seven biomarkers were significantly associated with overall (test–retest) measurement error (P = 0.003–0.007), and at least two others exhibited possible trends (P = 0.052–0.060). The weighted linear sum of all seven biomarkers was associated with overall measurement error, in both healthy eyes (r = 0.51, P < 0.001) and patients (r = 0.65, P < 0.001). Five biomarkers were each associated with failures to respond to visible stimuli on individual trials (all P < 0.001).

Conclusions

Inexpensive, autonomous measures of task compliance are associated with measurement error in visual field assessments, in terms of both the overall reliability of a test and failures to respond on particular trials (“lapses”). This could be helpful for identifying low-quality assessments and for improving assessment techniques (e.g., by discounting suspect responses or by automatically triggering comfort breaks or encouragement).

Translational Relevance

This study explores a potential way of improving the reliability of visual field assessments, a crucial but notoriously unreliable clinical measure.

An Open-source Static Threshold Perimetry Test Using Remote Eye-tracking (Eyecatcher): Description, Validation, and Preliminary Normative Data

Purpose

To describe, validate, and provide preliminary normative data for an open-source eye-movement perimeter (Eyecatcher).

Methods

Visual field testing was performed monocularly in 64 normally sighted young adults, using (i) a Humphrey Field Analyzer (HFA) and (ii) the novel Eyecatcher procedure. Eyecatcher used a remote eye-tracker to position stimuli relative to the current point of fixation, and observers responded by looking towards the stimulus. In both tests, Goldman III stimuli were sampled from a 24-2 grid, and were presented against a 10 cd/m² background. Participants completed each test twice to assess test–retest repeatability.

Results

Mean Sensitivity (MS) did not differ between Eyecatcher and the HFA (P = 0.086), and both tests exhibited similar test–retest repeatability (CoR_Eyecatcher = ±1.86 dB; CoR_HFA = ±1.95 dB). Eyecatcher was also able to detect changes in sensitivity across the normal visual field (the “Hill of Vision”), and could differentiate the physiological blind spot from adjacent retinal locations. Mean sensitivities and 95% limits of agreement are described for each pointwise location.

Conclusions

Eyecatcher can use eye movements to assess visual fields in young, normally sighted adults. In such observers, it provides results similar to the current gold standard clinical device (HFA).

Translational Relevance

Given further development, eye movement perimeters such as Eyecatcher could be particularly useful for individuals unable to perform traditional perimetric assessments, such as young children or stroke patients. Full technical details and information on how to freely acquire the source code are included.

Using eye movements to detect visual field loss: a pragmatic assessment using simulated scotoma

Glaucoma is a leading cause of irreversible sight-loss and has been shown to affect natural eye-movements. These changes may provide a cheap and easy-to-obtain biomarker for improving disease detection. Here, we investigated whether these changes are large enough to be clinically useful. We used a gaze-contingent simulated visual field (VF) loss paradigm, in which participants experienced a variable magnitude of simulated VF loss based on longitudinal data from a real glaucoma patient (thereby controlling for other variables, such as age and general health). Fifty-five young participants with healthy vision were asked to view two short videos and three pictures, either with: (1) no VF loss, (2) moderate VF loss, or (3) advanced VF loss. Eye-movements were recorded using a remote eye tracker. Key eye-movement parameters were computed, including saccade amplitude, the spread of saccade endpoints (bivariate contour ellipse area), location of saccade landing positions, and similarity of fixations locations among participants (quantified using kernel density estimation). The simulated VF loss caused some statistically significant effects in the eye movement parameters. Yet, these effects were not capable of consistently identifying simulated VF loss, despite it being of a magnitude likely easily detectable by standard automated perimetry.

Refinement and preliminary evaluation of two tablet-based tests of real-world visual function

Purpose

To describe, refine, evaluate, and provide normative control data for two freely available tablet‐based tests of real‐world visual function, using a cohort of young, normally‐sighted adults.

Methods

Fifty young (18–40 years), normally‐sighted adults completed tablet‐based assessments of (1) face discrimination and (2) visual search. Each test was performed twice, to assess test‐retest repeatability. Post‐hoc analyses were performed to determine the number of trials required to obtain stable estimates of performance. Distributions were fitted to the normative data to determine the 99% population‐boundary for normally sighted observers. Participants were also asked to rate their comprehension of each test.

Results

Both tests provided stable estimates in around 20 trials (~1–4 min), with only a further reduction of 14%–17% in the 95% Coefficient of Repeatability (CoR₉₅) when an additional 40 trials were included. When using only ~20 trials: median durations for the first run of each test were 191 s (Faces) and 51 s (Search); test‐retest CoR₉₅ were 0.27 d (Faces) and 0.84 s (Search); and normative 99% population‐limits were 3.50 d (Faces) and 3.1 s (Search). No participants exhibited any difficulties completing either test (100% completion rate), and ratings of task‐understanding were high (Faces: 9.6 out of 10; Search: 9.7 out of 10).

Conclusions

This preliminary assessment indicated that both tablet‐based tests are able to provide simple, quick, and easy‐to‐administer measures of real‐world visual function in normally‐sighted young adults. Further work is required to assess their accuracy and utility in older people and individuals with visual impairment. Potential applications are discussed, including their use in clinic waiting rooms, and as an objective complement to Patient Reported Outcome Measures (PROMs).

Severity of Visual Field Loss at First Presentation to Glaucoma Clinics in England and Tanzania

Purpose: To compare severity of visual field (VF) loss at first presentation in glaucoma clinics in England and Tanzania.Methods: Large archives of VF records from automated perimetry were used to retrospectively examine vision loss at first presentation in glaucoma clinics in Tanzania (N = 1,502) and England (N = 9,264). Mean deviation (MD) of the worse eye at the first hospital visit was used as an estimate of detectable VF loss severity.Results: In Tanzania, 44.7% {CI_95%: 42.2, 47.2} of patients presented with severe VF loss (< -20 dB), versus 4.6% {4.1, 5.0} in England. If we consider late presentation to also include cases of advanced loss (-12.01 dB to -20 dB), then the proportion of patients presenting late was 58.1% {55.6, 60.6} and 14.0% {13.3, 14.7}, respectively. The proportion of late presentations was greater in Tanzania at all ages, but the difference was particularly pronounced among working-age adults, with 50.3% {46.9, 53.7} of 18-65-year-olds presenting with advanced or severe VF loss, versus 10.2% {9.3, 11.3} in England. In both countries, men were more likely to present late than women.Conclusions: Late presentation of glaucoma is a problem in England, and an even greater challenge in Tanzania. Possible solutions are discussed, including increased community eye-care, and a more proactive approach to case finding through the use of disruptive new technologies, such as low-cost, portable diagnostic aids.

Novel Means of Clinical Visual Function Testing among Glaucoma Patients, Including Virtual Reality

Computed perimetry remains the gold standard of visual field measurement among glaucoma patients. However, several emerging technologies, made possible by advances in computer programming, smartphone, tablet, or virtual reality, allow alternative means of visual function assessment. These new visual tests may one day have a useful complementary role in visual field testing and to bridge the gap between perimetry and daily experience. Many of these emerging technologies have distinct practical advantages over Ganzfield bowl-based computed perimetry. This paper outlines a discussion of some of these emerging techniques in visual function assessment in glaucoma.