Photometric Compliance of Tablet Screens and Retro-Illuminated Acuity Charts As Visual Acuity Measurement Devices

Validation of a method to assess night myopia in a clinical setting

A study was conducted with 115 subjects who regularly drove at night to validate a refraction protocol for detecting refractive visual changes from daytime to nighttime conditions. Objective and subjective refractions were performed in both photopic and mesopic conditions, with a dark adaptation period before the mesopic subjective refraction. The results showed that in mesopic conditions, visual acuity decreased by 0.2 logMAR units on average (p < 0.01), and there was a myopic refractive shift of - 0.36 ± 0.20 D (p < 0.01). Most subjects (92.2%) exhibited a myopic refractive shift of at least 0.12 D. Compensation of refractive shift improved mesopic visual acuity by 0.06 logMAR on average (p < 0.01) and higher refractive shifts showed higher improvement. Night Rx was preferred by 82.1% of subjects with myopic refractive shift. Gender and age did not significantly affect the refractive shift, although myopes showed a higher shift compared to emmetropes (p < 0.01). The refractive shift remained stable over time when the time slot of the day did not change (p < 0.01). Night Rx protocol proved to be a robust and accurate method for identifying drivers with refractive changes when transitioning from photopic to mesopic conditions. The high prevalence and inter-individual variability of Rx shift highlight the need of customized refraction.

Development and validation of a new method for visual acuity assesment on tablet in pediatric population: eMOVA test

BACKGROUND

Amblyopia is a major public health concern. Its screening and management require reliable methods of visual acuity assessment. New technologies offer nowadays many tests available on different app stores for smartphone or tablet but most of them often lack of scientific validation for a medical use. The aim of our study was to attempt validating a tablet-based near visual acuity test adapted to the pediatric population: the eMOVA test (electronic Measurement Of Visual Acuity) by comparing visual acuity measured with more conventional test.

METHODS

A cohort of 100 children aged 3 to 8 attending the ophthalmic-pediatric for eye examination between September 2016 and June 2017 were included in the study. Near visual acuity was assessed on participants using both the eMOVA test and a Standard test (Rossano-Weiss test). Duration of each test, its comprehension, its acceptability and the attention of the child during the test was also investigated.

RESULTS

The eMOVA test overestimated near visual acuity by 0.06 logMAR. This difference, statistically significant, was not clinically relevant. The duration of the eMOVA test was longer than the reference test, but less discomfort and preferred by children and their parents compared to standard tests.

CONCLUSION

The eMOVA test appears as a reliable test to assess near visual acuity in children. By its portability and efficiency, this application proved to be a relevant tool to be used for children eye examination in daily routine at the hospital.

Age norms for grating acuity and contrast sensitivity in children using eye tracking technology

KEY MESSAGES

Visual acuity is the most used method to assess visual function in children. Contrast sensitivity complements the information provided for visual acuity, but it is not commonly used in clinical practice. Digital devices are increasingly used as a method to evaluate visual function, due to multiple advantages. Testing with these devices can improve the evaluation of visual development in children from a few months of age. Visual acuity and contrast sensitivity tests, using eye tracking technology, are able to measure visual function in children across a wide range of ages, objectively, quickly and without need of an experienced examiner.

PURPOSE

To report age-normative values for grating visual acuity and contrast sensitivity in healthy children using a digital device with eye tracking technology and to validate the grating acuity test.

METHODS

In the first project of the study, we examined healthy children aged between 6 months and 7 years with normal ophthalmological assessment. Grating visual acuity (VA) and contrast sensitivity (CS) were assessed using a preferential gaze paradigm with a DIVE (Device for an Integral Visual Examination) assisted with eye tracking technology to provide age norms. For the validation project, we compared LEA grating test (LGT) with DIVE VA in a group of children aged between 6 months and 4 years with normal and abnormal visual development.

RESULTS

Fifty-seven children (2.86 ± 1.55 years) were examined with DIVE VA test and 44 successfully completed DIVE CS test (3.06 ± 1.41 years). Both, VA and CS values increased with age, mainly along the first two years of life. Sixty-nine patients (1.34 ± 0.61 years) were included in the DIVE VA test validation. The mean difference between LGT and DIVE VA was - 1.05 ± 4.54 cpd with 95% limits of agreement (LoA) of - 9.95-7.84 cpd. Agreement between the two tests was higher in children younger than 1 year with a mean difference of - 0.19 ± 4.02 cpd.

CONCLUSIONS

DIVE is an automatic, objective and reliable tool to assess several visual function parameters in children, and it has good agreement with classical VA tests, especially for the first stage of life.

Too Many Shades of Grey: Photometrically and Spectrally Mismatched Targets and Backgrounds in Printed Acuity Tests for Infants and Young Children

Purpose

Acuity tests for infants and young children use preferential looking methods that require a perceptual match of brightness and color between grey background and target spatial average. As a first step in exploring this matching, this article measures photometric and colorimetric matches in these acuity tests.

Methods

The luminance, uniformity, contrast, and color spectra of Teller Acuity Cards, Keeler Acuity Cards for Infants, and Lea Paddles under ambient, warm, and cold lighting, and of grey-emulating patterns on four digital displays, were measured. Five normal adults' acuities were tested at 10 m observationally.

Results

Luminance and spectral mismatches between target and background were found for the printed tests (Weber contrasts of 0.3% [Teller Acuity Cards], -1.7% [Keeler Acuity Cards for Infants], and -26% [Lea Paddles]). Lighting condition had little effect on contrast, and all printed tests and digital displays met established adult test luminance and uniformity standards. Digital display grey backgrounds had very similar luminance and color whether generated by a checkerboard, vertical grating, or horizontal grating. Improbably good psychophysical acuities (better than -0.300 logMAR: (logarithm of the minimum angle of resolution)) were recorded from adults using the printed tests at 10 m, but not using the digital test Peekaboo Vision.

Conclusions

Perceptible contrast between target and background could lead to an incorrectly measured, excessively good acuity. It is not clear whether the luminance and spectral contrasts described here have clinically meaningful consequences for the target patient group, but they may be avoidable using digital tests.

Translational Relevance

Current clinical infant acuity tests present photometric mismatches that may return inaccurate testing results.

Validation of the visual acuity iPad app Eye Chart Pro compared to the standard Early Treatment Diabetic Retinopathy Study chart in a low-vision population

INTRODUCTION

A low-vision assessment (LVA) is central to developing a vision rehabilitation plan. However, access to LVAs is often limited by the quantity and geographic distribution of low-vision providers, as well as patient-centred transportation challenges. A tablet-based LVA tool kit, delivered virtually, has the potential to overcome many of these barriers. The purpose of this research was to validate a key component of the tablet-based tool kit - a commercially available iPad visual acuity (VA) test (Eye Chart Pro) iPad app - in a low-vision population.

METHODS

Participants with low vision (n = 26) and those who were normally sighted (n = 25) underwent VA testing with both the iPad VA test application and the Early Treatment Diabetic Retinopathy Study (ETDRS) chart. The VA data were compared using a t-test, linear regression and Bland-Altman analysis.

RESULTS

There was no significant difference in the mean absolute difference in VA (log of minimum angle of resolution (logMAR)=0.11; p = 0.82). Eye Chart Pro and Standard ETDRS Chart measures were also not significantly different (p = 0.98). However, there were significant differences between test methods in the low-vision group and the normally sighted group (p > 0.0001 and p = 0.007, respectively). The Bland-Altman analysis showed a mean bias (difference) of -0.0005 logMAR between methods, and 95% limits of agreement of 0.298 and -0.299 logMAR.

DISCUSSION

The ETDRS chart function on the Eye Chart Pro application can reliably measure VA across a range, from normally sighted patients to those with low vision.

Screen and Virtual Reality-Based Testing of Contrast Sensitivity

Contrast sensitivity is a key visual ability for everyday tasks, as well as a potential indicator of important optical and neurological diseases. Current clinical standards, based on visual discrimination performance on printed charts, present problems that could be bypassed using electronic devices. This work describes the development of new tests for contrast sensitivity, based on the detection of a moving target on a computer screen and in virtual reality headset. It presents preliminary evaluation of these innovations by comparison of their performance, using healthy adults with normal vision and by artificially altering their contrast sensitivity. The results demonstrate consistent correlation between all test modalities explored.

Use of the King-Devick Variable Color Contrast Sensitivity Chart to differentiate stages of age-related macular degeneration

Objective

This study aimed to determine which colour contrast sensitivity differences exist in early to advanced age-related macular degeneration (AMD) and examine the potential utility of the King-Devick Variable Color Contrast Sensitivity Chart in detecting AMD severity.

Methods and analysis

A total of 85 participants (144 total eyes) were recruited from multiple clinical practices and enrolled in the study. The control group consisted of 57 healthy eyes. The non-exudative AMD (NE-AMD) group consisted of 45 eyes. The exudative AMD (E-AMD) group consisted of 42 eyes. In a single study visit, monocular best-corrected visual acuity (BCVA) at 40 cm with 100% black contrast was determined for each eye. Using the BCVA line, the number of letters correctly identified (out of 10) was recorded for various colour presentations (red, green, blue and yellow) and at decreasing contrast levels (100%, 75%, 50% and 25%).

Results

Our results show worse visual performance under various colour contrast settings in E-AMD patients compared with healthy controls and NE-AMD. Colour contrast performance using blue and yellow differentiated more advanced stages of disease in E-AMD from earlier NE-AMD disease. Blue and black colour contrast performance more accurately identified the E-AMD group from healthy controls and the NE-AMD group.

Conclusion

The findings of this study demonstrate that colour contrast, particularly with black, blue and yellow, is impaired in E-AMD suggesting the potential for colour contrast measures to serve as an adjunctive clinical tool in identifying subtle altered visual function as well as the potential for detecting disease severity.

Community health workers obtain similar results using cell-phone based hearing screening tools compared to otolaryngologists in low resourced settings

OBJECTIVE

To establish community health workers as reliable hearing screening operators in a technology-based pre-surgical hearing screening program in a low and middle-income country (LMIC).

METHODS

This is a cross sectional study that evaluated community health worker driven hearing screening that took place in semi-rural Malindi, Kenya during an annual two-week otolaryngology surgical training mission in October 2017. At five separate locations (four schools) near Malindi, Kenya, children between the ages of 2-16 underwent hearing screening using screening audiometry (Android-based HearX Group). Children were screened by a community health worker who underwent a short training course, a senior otolaryngology resident, or both. Hearing screening results were compared to determine the reliability and concordance between independent, blinded community health worker and otolaryngology resident testing.

RESULTS

One hundred and four participants (53% males) underwent hearing screening. Hearing screening pass rate was 93%. Community health workers obtained a similar result to otolaryngology residents 96% of the time (McNemar test: p = 0.16, OR 0.96, 95% CI 0.9-1.0).

CONCLUSION

Community health workers can obtain reliable results using a technology-based, pre-surgical hearing screening platform when compared to otolaryngology residents. This finding has profound implications in low-resourced settings where hearing healthcare specialists (audiologists and otolaryngologists) are limited and can ultimately improve the surgical yield of patients presenting to local otolaryngologists in these settings.

Accuracy and Feasibility of an Android-Based Digital Assessment Tool for Post Stroke Visual Disorders-The StrokeVision App

Background

Visual impairment affects up to 70% of stroke survivors. We designed an app (StrokeVision) to facilitate screening for common post stroke visual issues (acuity, visual fields, and visual inattention). We sought to describe the test time, feasibility, acceptability, and accuracy of our app-based digital visual assessments against (a) current methods used for bedside screening and (b) gold standard measures.

Methods

Patients were prospectively recruited from acute stroke settings. Index tests were app-based assessments of fields and inattention performed by a trained researcher. We compared against usual clinical screening practice of visual fields to confrontation, including inattention assessment (simultaneous stimuli). We also compared app to gold standard assessments of formal kinetic perimetry (Goldman or Octopus Visual Field Assessment); and pencil and paper-based tests of inattention (Albert's, Star Cancelation, and Line Bisection). Results of inattention and field tests were adjudicated by a specialist Neuro-ophthalmologist. All assessors were masked to each other's results. Participants and assessors graded acceptability using a bespoke scale that ranged from 0 (completely unacceptable) to 10 (perfect acceptability).

Results

Of 48 stroke survivors recruited, the complete battery of index and reference tests for fields was successfully completed in 45. Similar acceptability scores were observed for app-based [assessor median score 10 (IQR: 9-10); patient 9 (IQR: 8-10)] and traditional bedside testing [assessor 10 (IQR: 9-10); patient 10 (IQR: 9-10)]. Median test time was longer for app-based testing [combined time to completion of all digital tests 420 s (IQR: 390-588)] when compared with conventional bedside testing [70 s, (IQR: 40-70)], but shorter than gold standard testing [1,260 s, (IQR: 1005-1,620)]. Compared with gold standard assessments, usual screening practice demonstrated 79% sensitivity and 82% specificity for detection of a stroke-related field defect. This compares with 79% sensitivity and 88% specificity for StrokeVision digital assessment.

Conclusion

StrokeVision shows promise as a screening tool for visual complications in the acute phase of stroke. The app is at least as good as usual screening and offers other functionality that may make it attractive for use in acute stroke.

Clinical Trial Registration

https://ClinicalTrials.gov/ct2/show/NCT02539381.

Expanding the Capacity of Otolaryngologists in Kenya through Mobile Technology

Objective

To determine if reliable, objective audiologic data can be obtained by nonotolaryngology and nonaudiology practitioners using novel mobile technology in an effort to expand the capacity for early identification and treatment of disabling hearing loss in the developing world.

Study Design

Cross-sectional, proof-of-concept pilot study.

Setting

Screenings took place during an annual 2-week otolaryngology surgical mission in October 2016 in semirural Malindi, Kenya.

Subject and Methods

Eighty-seven patients (174 total ears) were included from 2 deaf schools (n = 12 and 9), a nondeaf school (n = 9), a tuberculosis ward (n = 8), and a walk-in otology clinic at a local hospital (n = 49). An automated, tablet-based, language-independent, clinically validated, play audiometry system and wireless otoscopic endoscopy via an iPhone or laptop platform was administered by Kenyan community health workers (CHWs) and nursing staff.

Results

Various degrees of hearing loss and otologic pathology were identified, including 1 child presumed to be deaf who was found to have unilaterally normal hearing. Other pathology included 2 active perforations, 2 healed perforations, 2 middle ear effusions, and 1 cholesteatoma. CHWs and nursing staff demonstrated proficiency performing audiograms and endoscopy. Patients screened in a deaf school were more likely to complete an unreliable audiogram than patients screened in other settings (P < .01).

Conclusion

This study demonstrates the feasibility of a non–otolaryngology-based hearing screening program. This may become an important tool in reducing the impact of hearing loss and otologic pathology in areas bereft of otolaryngologists and audiologists by allowing CHWs to gather important patient data prior to otolaryngologic evaluation.

Testing Pediatric Acuity With an iPad: Validation of "Peekaboo Vision" in Malawi and the UK

Purpose

To evaluate two builds of the digital grating acuity test, “Peekaboo Vision” (PV), in young (6–60 months) populations in two hospital settings (Malawi and United Kingdom).

Methods

Study 1 evaluated PV in Blantyre, Malawi (N = 58, mean age 33 months); study 2 evaluated an updated build in Glasgow, United Kingdom (N = 60, mean age 44 months). Acuities were tested-retested with PV and Keeler Acuity Cards for Infants (KACI). Bland-Altman techniques were used to compare results and repeatability. Child engagement was compared between groups. Study 2 included test-time comparison.

Results

Study 1 (Malawi): The mean difference between PV and KACI was 0.02 logMAR with 95% limits of agreement (LoA) of 0.33 to 0.37 LogMAR. On test-retest, PV demonstrated 95% LoA of −0.283 to 0.198 logMAR with coefficient of repeatability (CR) 0.27. KACI demonstrated 95% LoA of −0.427 to 0.323 logMAR, and larger CR was 0.37. PV evidenced higher engagement scores than KACI (P = 0.0005). Study 2 (UK): The mean difference between PV and KACI was 0.01 logMAR; 95% LoA was −0.413 to 0.437 logMAR. Again, on test-retest, PV had narrower LoA (−0.344 to 0.320 logMAR) and lower CR (0.32) versus KACI, with LoA −0.432 to 0.407 logMAR, CR 0.42. The two tests did not differ in engagement score (P = 0.5). Test time was ∼1 minute shorter for PV (185 vs. 251 s, P = 0.0021).

Conclusions

PV gives comparable results to KACI in two pediatric populations in two settings, with benefits in repeatability indices and test duration.

Translational Relevance

Leveraging tablet technology extends reliable infant acuity testing to bedside, home, and rural settings, including areas where traditional equipment cannot be financed.

Comparing performance on the MNREAD iPad application with the MNREAD acuity chart

Our purpose was to compare reading performance measured with the MNREAD Acuity Chart and an iPad application (app) version of the same test for both normally sighted and low-vision participants. Our methods included 165 participants with normal vision and 43 participants with low vision tested on the standard printed MNREAD and on the iPad app version of the test. Maximum Reading Speed, Critical Print Size, Reading Acuity, and Reading Accessibility Index were compared using linear mixed-effects models to identify any potential differences in test performance between the printed chart and the iPad app. Our results showed the following: For normal vision, chart and iPad yield similar estimates of Critical Print Size and Reading Acuity. The iPad provides significantly slower estimates of Maximum Reading Speed than the chart, with a greater difference for faster readers. The difference was on average 3% at 100 words per minute (wpm), 6% at 150 wpm, 9% at 200 wpm, and 12% at 250 wpm. For low vision, Maximum Reading Speed, Reading Accessibility Index, and Critical Print Size are equivalent on the iPad and chart. Only the Reading Acuity is significantly smaller (I. E., better) when measured on the digital version of the test, but by only 0.03 logMAR (p = 0.013). Our conclusions were that, overall, MNREAD parameters measured with the printed chart and the iPad app are very similar. The difference found in Maximum Reading Speed for the normally sighted participants can be explained by differences in the method for timing the reading trials.