Amblyopia Suspect, Visual Impairment
Conditions
Brief summary
This trial aims to assess the accuracy and test-retest variability of a new digital app which enables community visual acuity testing without requirement of an trained examiner.
Detailed description
Eye problems like macular degeneration and amblyopia (lazy eye) require regular monitoring to prevent permanent visual impairment. Over 2000 patients a month are seen in Cambridge University Hospitals National Health Service Trust (CUH) eye clinics; concern about Covid-19 infection has led to over 80% of consultations being conducted by telephone with few clinical clues to inform decision making. Patients will face long delays even when routine clinics restart: there is no doubt that some will suffer preventable visual loss. DigiVis is a web-based vision testing app enabling self-testing of vision at home. Early testing and patient feedback is positive: 80% of children prefer DigiVis to regular testing. The investigators wish to test how accurately the app works for home use, by asking older children and adults to self-test their vision prior to their planned face to face clinic appointment. Once tested, DigiVis will be available free of charge to patients, not only during the Covid-19 crisis, but also to support telephonic consultations in the future. Visual acuity (VA) is a fundamental measure of vision required for all ophthalmic assessments. It is measured by health professionals using vision charts. DigiVis is a new app which enables self-testing of VA using two wirelessly connected digital devices. By matching letters on a handheld device to those displayed on the second device a distance away, threshold VA can be measured using a staircase algorithm. The distance and scaling of the test is vital to its accuracy and a concept (patent filed by Cambridge Enterprise) in DigiVis enables this without the need for manual distance measurement or an observer. Early validation using two tablet computers in 150 clinic patients has given positive results, both in testing accuracy and patient feedback. With the current Covid-19 crisis limiting face to face appointments, there is an urgent need for accurate home VA assessment. The DigiVis app has been re-coded for free website delivery for this purpose. The investigators wish to formally validate DigiVis home testing following Conformitè Europëenne (CE class I) marking so that it can be recommended for clinical use. 250 patients will be invited to self-test their VA twice using DigiVis prior to a planned face to face clinic appointment. The test-retest variability and comparison of DigiVis VA to chart based assessment will be compared.
Interventions
DEVICEDigiVis visual acuity app
Self-testing of visual acuity app on two occasions
Sponsors
Cambridge University Hospitals NHS Foundation Trust
Study design
Allocation
NA
Intervention model
SEQUENTIAL
Primary purpose
SCREENING
Masking
NONE
Intervention model description
Patients will test their own vision twice using the DigiVis app twice, subsequently they will have visual acuity assessment in eye clinic by a trained examiner. The results of visual acuity will be compared using Bland Altman statistical analysis.
Eligibility
Sex/Gender
ALL
Age
5 Years to 85 Years
Healthy volunteers
Yes
Inclusion criteria
* Age between 5 and 85 years * Previous recorded visual acuity of at least +0.8 logMAR in or both eyes
Exclusion criteria
* Individuals with poor conversant English * Individuals with cognitive impairment * Subjects unable to access the internet on two digital devices
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Mean Bias Between the Difference Between DigiVis and Standard Visual Assessment Compared to the Mean of DigiVis and Standard Visual Assessment | within 30 days | The mean bias (difference) in visual acuity assessment score between the difference in DigiVis and standard testing in logMAR units and the mean of DigiVis and standard testing in logMAR units was calculated. Where 0.00 logMAR is the value representing perfect distance visual acuity (equivalent to 20/20 Snellen acuity) and 1.00 logMAR is the value representing worst distance visual acuity (equivalent to 20/200 Snellen acuity). |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Mean Bias Between Repeated DigiVis Test Assessments | within 30 days | Mean bias between the difference of two DigiVis visual acuity assessments compared to the mean of two digiVis assessments measured in logMAR units. |
Countries
United Kingdom
Participant flow
Recruitment details
Over a two month period, research administrators posted study invitations and information leaflets to all patients due to attend an eye clinic appointment. Inclusion criteria were: age over 4 years, VA of +0.8 (6/38 Snellen) or better in each eye and no documentation of cognitive disability. The clinician researcher phoned the patient to explain the study, take verbal consent and give password access to the DigiVis test.
Pre-assignment details
All participants underwent both the DigiVis testing and the standard clinical visual acuity test.
Participants by arm
| Arm | Count |
|---|---|
| All Study Participants Right eye data for all 120 participants to the study. | 120 |
| Total | 120 |
Baseline characteristics
| Characteristic | All Study Participants | — |
|---|---|---|
| Age, Customized Age category 11-54 years | 37 Participants | — |
| Age, Customized Age category 5-10 years | 44 Participants | — |
| Age, Customized Age category 55 - 75 years | 32 Participants | — |
| Age, Customized Age category 76-85 | 7 Participants | — |
| Race and Ethnicity Not Collected | — | — Participants |
| Sex: Female, Male Female | 66 Participants | — |
| Sex: Female, Male Male | 54 Participants | — |
Adverse events
| Event type | EG000 affected / at risk |
|---|---|
| deaths Total, all-cause mortality | 0 / 120 |
| other Total, other adverse events | 0 / 120 |
| serious Total, serious adverse events | 0 / 120 |
Outcome results
Primary
Mean Bias Between the Difference Between DigiVis and Standard Visual Assessment Compared to the Mean of DigiVis and Standard Visual Assessment
The mean bias (difference) in visual acuity assessment score between the difference in DigiVis and standard testing in logMAR units and the mean of DigiVis and standard testing in logMAR units was calculated. Where 0.00 logMAR is the value representing perfect distance visual acuity (equivalent to 20/20 Snellen acuity) and 1.00 logMAR is the value representing worst distance visual acuity (equivalent to 20/200 Snellen acuity).
Time frame: within 30 days
Population: All participants had their right eye tested firstly with the standard chart technique and subsequently with DigiVis
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Standard Vision Testing | Mean Bias Between the Difference Between DigiVis and Standard Visual Assessment Compared to the Mean of DigiVis and Standard Visual Assessment | 0.112 logMAR | Standard Deviation 0.247 |
| DigiVis Vision Testing | Mean Bias Between the Difference Between DigiVis and Standard Visual Assessment Compared to the Mean of DigiVis and Standard Visual Assessment | 0.100 logMAR | Standard Deviation 0.27 |
Secondary
Mean Bias Between Repeated DigiVis Test Assessments
Mean bias between the difference of two DigiVis visual acuity assessments compared to the mean of two digiVis assessments measured in logMAR units.
Time frame: within 30 days
Population: Participants able to undertake DigiVis testing twice to analyse test repeatability
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Standard Vision Testing | Mean Bias Between Repeated DigiVis Test Assessments | 0.100 logMAR | Standard Deviation 0.27 |
| DigiVis Vision Testing | Mean Bias Between Repeated DigiVis Test Assessments | 0.105 logMAR | Standard Deviation 0.258 |