New rarebit vision test captures macular deficits hidden to acuity tests

Home vision monitoring in patients with maculopathy: current and future options for digital technologies

Patients with macular pathology, including that caused by age-related macular degeneration and diabetic macular oedema, must attend frequent in-clinic monitoring appointments to detect onset of disease activity requiring treatment and to monitor progression of existing disease. In-person clinical monitoring places a significant burden on patients, caregivers and healthcare systems and is limited in that it only provides clinicians with a snapshot of the patient's disease status. The advent of remote monitoring technologies offers the potential for patients to test their own retinal health at home in collaboration with clinicians, reducing the need for in-clinic appointments. In this review we discuss visual function tests, both existing and novel, that have the potential for remote use and consider their suitability for discriminating the presence of disease and progression of disease. We then review the clinical evidence supporting the use of mobile applications for monitoring of visual function from clinical development through to validation studies and real-world implementation. This review identified seven app-based visual function tests: four that have already received some form of regulatory clearance and three under development. The evidence included in this review shows that remote monitoring offers great potential for patients with macular pathology to monitor their condition from home, reducing the need for burdensome clinic visits and expanding clinicians' understanding of patients' retinal health beyond traditional clinical monitoring. In order to instil confidence in the use of remote monitoring in both patients and clinicians further longitudinal real-world studies are now warranted.

Patient Acceptability of Home Monitoring for Neovascular Age-Related Macular Degeneration Reactivation: A Qualitative Study

Neovascular age-related macular degeneration (nAMD) is a chronic, progressive condition and the commonest cause of visual disability in older adults. This study formed part of a diagnostic test accuracy study to quantify the ability of three index home monitoring (HM) tests (one paper-based and two digital tests) to identify reactivation in nAMD. The aim of this qualitative research was to investigate patients' or participants' views about acceptability and explore adherence to weekly HM. Semi-structured interviews were held with 78/297 participants (26%), with close family members (n = 11) and with healthcare professionals involved in training participants in HM procedures (n = 9) (n = 98 in total). A directed thematic analytical approach was applied to the data using a deductive and inductive coding framework informed by theories of technology acceptance. Five themes emerged related to: 1. The role of HM; 2. Suitability of procedures and instruments; 3. Experience of HM; 4. Feasibility of HM in usual practice; and 5. Impediments to patient acceptability of HM. Various factors influenced acceptability including a patient's understanding about the purpose of monitoring. While initial training and ongoing support were regarded as essential for overcoming unfamiliarity with use of digital technology, patients viewed HM as relatively straightforward and non-burdensome. There is a need for further research about how use of performance feedback, level of support and nature of tailoring might facilitate further the implementation of routinely conducted HM. Home monitoring was acceptable to patients and they recognised its potential to reduce clinic visits during non-active treatment phases. Findings have implications for implementation of digital HM in the care of older people with nAMD and other long-term conditions.

Monitoring for neovascular age-related macular degeneration (AMD) reactivation at home: the MONARCH study

AIMS

This study aims to quantify the diagnostic test-accuracy of three visual function self-monitoring tests for detection of active disease in patients with neovascular age-related macular degeneration (nAMD) when compared with usual care. An integrated qualitative study will investigate the acceptability of these home-based testing strategies.

METHODS

All consenting participants are provided with an equipment pack containing an iPod touch with two vision test applications installed and a paper journal of reading tests. Participants self-monitor their vision at home each week with all three tests for 12-18 months. Usual care continues over this period. Key eligibility criteria are: age ≥50 years; at least one eye with AMD with ≥6-≤42 months since first AMD treatment; and vision not worse than Snellen 6/60, LogMAR 1.04 or 33 letters. The primary outcome, and reference standard, is diagnosis of active disease during usual care monitoring in the Hospital Eye Service. Secondary outcomes include duration of study participation, ability of participants to do the tests, adherence to weekly testing and acceptability of the tests to participants.

CONCLUSIONS

Recruitment is in progress at five NHS centres. Challenges in procuring equipment, setting up the devices and transporting devices containing lithium batteries to participating sites delayed the start of recruitment. The study will describe the performance of the tests self-administered at home in detecting active disease compared to usual care monitoring. It will also describe the feasibility of the NHS implementing patient-administered electronic tests or similar applications at home for monitoring health.

Detection of Progression With 10-2 Standard Automated Perimetry: Development and Validation of an Event-Based Algorithm

PURPOSE

To describe the development of a new algorithm for detecting progressive changes in 10-2 visual field (VF) tests using event-based analysis and to test its validity in a second, independent glaucoma cohort.

DESIGN

Prospective cohort study.

METHODS

Patients with established open-angle glaucoma from the Macular Assessment and Progression Study (MAPS; development cohort, n = 151), and the African Descent and Glaucoma Evaluation Study (ADAGES; validation cohort, n = 52) were evaluated. The 10-2 VF results from MAPS were obtained during 4 test-retest sessions within a 4-month period. For the validation analysis, 10-2 VF results from ADAGES performed on at least 5 visits were used. The event-based pointwise changes on 10-2 tests in the validation cohort were determined using 2 progression criteria: at least 3 progressing VF locations on 2 or 3 consecutive tests ("possible" or "likely" progression). Linear mixed-effects models were used to evaluate VF progression.

RESULTS

In the validation cohort, the mean (SD) follow-up time was 2.3 (0.7) years. The number of eyes experiencing 10-2 VF progression based on "possible" and "likely" progression was 36 (54.5%) and 11 (16.6%), respectively. Eyes experiencing "possible" progression had MD changes (-0.60 dB/year [95% confidence interval (CI): -0.93 to -0.28]) faster than those not meeting this criterion (P < .001), whereas for those with "likely" progression the difference was -0.91 dB/year (95% CI: -1.26 to -0.56, P < .001).

CONCLUSIONS

A new event-based progression algorithm using the 10-2 VF can identify eyes experiencing more rapid MD progression and may be used as a tool to assess progressive macular functional changes in glaucoma.

Testing the visual field of children and adults with Rarebit: The role of task repetition on sensitivity

Rarebit is a simple and user-friendly perimetry that tests the visual field by using tiny supra-threshold dot stimuli. It appears to be especially useful for examining the visual field of children who are under 12 years of age. However, previous data showed that the number of errors was higher in children than adults. We ask whether the different number of errors in these two groups depended on task learning and whether it may be accounted for by sensitivity differences or a response bias. Thirty-one children between 9 and 12 years of age and thirty-nine adults were tested three times with Rarebit perimetry. A bias-free sensitivity index, d', rather than the simple hit rate, revealed a group difference that remained after extensive task repetition. Indeed, d' increased with task learning in a similar way in the two groups so that group difference remained after practice. The response bias differed in the two groups, being conservative in the older group (criterion C >0) and liberal in the younger (criterion C < 0). Both biases disappeared with task learning in the third session, suggesting that response bias cannot account for the group difference in sensitivity after practice. When bias-free measures of sensitivity are used and task learning effects are minimized, Rarebit perimetry may be a more valuable method than simple mean hit rate (MHR) to enlighten sensitivity differences in the visual field assessment within the pediatric population.

Impact of simulated micro-scotomas on reading performance in central and peripheral retina

Observers with central field loss typically fixate within a non-foveal region called the preferred retinal locus, which can include localized sensitivity losses, or micro-scotomas (Krishnan and Bedell, 2018). In this study, we simulated micro-scotomas at the fovea and in the peripheral retina to assess their impact on reading speed. Ten younger (<36 years old) and 8 older (>50 years old) naïve observers with normal vision monocularly read high and/or low contrast sentences, presented at or above the critical print size for young observers at the fovea and at 5 and 10 deg in the inferior visual field. Reading material comprised MNREAD sentences and sentences taken from novels that were presented in rapid serial visual presentation (RSVP) format. Randomly distributed 13 × 13 arc min blocks corresponding to 0-78% of the text area (corresponding to ∼0-17 micro-scotomas/deg2) were set to the background luminance to simulate micro-scotomas. A staircase algorithm estimated maximum reading speed from the threshold exposure duration for each combination of retinal eccentricity, contrast and micro-scotoma density in both age groups. Log10(RSVP reading speed) decreased significantly with simulated micro-scotoma density and eccentricity. Across conditions, reading speed was slower with low-compared to high-contrast text and was faster in younger than older normal observers. For a given eccentricity and contrast, a higher density of random element losses maximally affected older observers with normal vision. These outcomes may explain some of the reading deficits observed in older observers with central field loss.

Test Conditions in Macular Visual Field Testing in Glaucoma

PURPOSE

The purpose of this study is to evaluate the suitable visual field (VF) test conditions (target size, test type, and eccentricity) for the macular region, we investigated the correlations between the ganglion cell layer (GCL) thickness and 6 VF test results.

METHODS

We tested 32 eyes of patients (61.1±9.2 y) with preperimetric (6), early-stage (16), and moderate-stage (10) glaucoma. The VF tests included 3 SAP (the 10-2 HFA using SITA with target size III [HFA SITA (III)], full threshold with size III [HFA FULL (III)] and size I [HFA FULL (I)]) and 3 visual function-specific perimetry tests (the 10-2 SWAP, 10-2 flicker, and 10-2 Humphrey Matrix). The GCL and inner plexiform layer (GCL+IPL) thickness was measured by Spectral Domain Optical Coherence Tomography (SD-OCT) with a macular 7×7 mm cube scan (3D OCT-2000, Topcon). The coefficient of determination (r) for the correlation between visual sensitivity and the GCL+IPL thickness was calculated for each test at eccentricities 0 to 5 degrees, 5 to 7 degrees, and 7 to 10 degrees using linear and quadratic regressions.

RESULTS

All 6 tests showed the strongest correlation with the GCL+IPL thickness at 5 to 7 degrees. The respective r (linear) and R (quadratic) for HFA SITA (III), HFA FULL (III), HFA FULL (I), SWAP, Flicker, and Matrix were (0.40, 0.50), (0.43, 0.53), (0.44, 0.46), (0.51, 0.51), (0.33, 0.34), and (0.52, 0.52).

CONCLUSIONS

As compared with the frequently-used SAP with a size III, SAP with size I and the function-specific perimetry tests (especially the Matrix) could be more suitable for testing the macular region.

Functional changes at the preferred retinal locus in subjects with bilateral central vision loss

PURPOSE

Subjects with bilateral central vision loss (CVL) use a retinal region called the preferred retinal locus (PRL) for performing various visual tasks. We probed the fixation PRL in individuals with bilateral macular disease, including age-related macular degeneration (AMD) and Stargardt disease (STGD), for localized sensitivity deficits.

METHODS

Three letter words at the critical print size were presented in the NIDEK MP-1 microperimeter to determine the fixation PRL and its radial retinal eccentricity from the residual fovea in 29 subjects with bilateral CVL. Fixation stability was defined as the median bivariate contour ellipse area (BCEA) from 3 fixation assessments. A standard 10-2 grid (68 locations, 2° apart) was used to determine central retinal sensitivity for Goldmann size II test spots. Baseline and follow-up supra-threshold screening of the fixation PRL for localized sensitivity deficits was performed using high density (0.2° or 0.3° apart) 0 dB Goldmann size II test spots. Custom MATLAB code and a dual bootstrapping algorithm were used to register test-spot locations from the baseline and follow-up tests. Locations where the 0 dB test spots were not seen on either test were labeled as micro-scotomas (MSs).

RESULTS

Median BCEA correlated poorly with the radial eccentricity of the fixation PRL. Mean (±SD) sensitivity around the PRL from 10-2 testing was 4.93 ± 4.73 dB. The average percentage of MSs was similar for patients with AMD (25.4%), STGD (20.3%), and other etiologies of CVL (27.1%).

CONCLUSIONS

The fixation PRL in subjects with bilateral CVL frequently includes local regions of sensitivity loss.

Self-Testing of Vision in Age-Related Macula Degeneration: A Longitudinal Pilot Study Using a Smartphone-Based Rarebit Test

Purpose. There is a need for efficient self-tests of vision in patients with neovascular age-related macula degeneration. A new tablet/smartphone application aiming to meet this need is described and its performance is assessed in a longitudinal pilot study. Materials and Methods. The new MultiBit Test (MBT) employs segmented digits defined by rarebits, that is, receptive field-size bright dots briefly presented against a dark background. The number of rarebits per digit segment was varied in a cyclic fashion, in preset steps. There were no fixation demands. Twenty-eight patients with neovascular AMD of varying severity were monitored for an average of 30 weeks. Test scores were evaluated on an individual basis, by contrasting observed trends with the clinical status recorded at independently scheduled clinical examinations. Results. Serial plots of MBT results revealed gradual improvement after successful antineovascular treatment. Recurrences were signalled by gradual deteriorations of results. Test results remained stable during clinically stable time intervals. MBT results agreed well with clinical assessments whereas an acuity test performed at chance level. The MBT was well accepted by all subjects. Conclusions. The MBT appears to have a good potential for effective self-testing of vision in AMD and merits large-scale studies. Exploration of MBT performance with other forms of macula conditions may be worthwhile.