Plain English Summary
Background and study aims
Glaucoma is one of the leading causes of irreversible blindness worldwide. The disease generally does not cause symptoms early as it affects the side-vision or visual field first. Current standard visual field testing machines such as a Humphrey visual field machine are not easily portable and come at a high cost. The Apple iPad however is a popular consumer technology that is portable, relatively low cost and has a high quality screen suitable for vision testing. As part of the treatment of your eye condition you might have had visual field testing on a Humphrey visual field machine, where you are required to keep your eye focused on a point in the center and respond to a white spot shined in your side vision by clicking a button. The aim of this study is to compare visual field testing perform using the Apple iPad against the Humphrey visual field machine over a period of 6 months.
Who can participate?
Adults aged 18 and older who have glaucoma.
What does the study involve?
The participation in the study will last for up to six months for each patient. This is made up of a baseline visit, and visits at one, three, and six months. At each visit participants have their usual visual field test using Humphrey visual field and then visual field test using an iPad. Similar to the traditional Humphrey visual field test, each participant is asked to focus on a red fixation dot and press a button on the keyboard when you see a white spot appear in your side-vision. The software tests each eye separately and takes on average 5 minutes per eye, therefore takes about 10 minutes of testing time.In order to check if the iPad visual field software is able to produce consistent outcomes on multiple occasions across time, participants are also asked to complete the same iPad visual field test again at the one month, three month and six month visits.
What are the possible benefits and risks of participating?
There are no benefits or risks expected with participation.
Where is the study run from?
Addenbrooke's Cambridge University Hospital (UK)
When is the study starting and how long is it expected to run for?
April 2016 to October 2017
Who is funding the study?
Addenbrooke's Charitable Trust, Cambridge University Hospitals (UK)
Who is the main contact?
Dr Yu Xiang George Kong (Scientific)
Dr Yu Xiang George Kong
Addenbrooke's Hospital Ophthalmology Department
Cambridge University Hospitals NHS Foundation Trust
IRAS ID: 204698
Longitudinal assessment of visual field using iPad tablet computer for patients with glaucoma
Hypothesis is visual field test performed on iPad will be able to produce output measures that matches visual field test performed on the gold standard Humphrey visual field test.
Health Research Authority (HRA), 28/09/2016, ref: 204698
Longitudinal observational study
Primary study design
Secondary study design
Patient information sheet
See additional files
The participation in the study lasts for up to six months for each patient. This is made up of a baseline visit, and visits at one, three, and six months.
At each visit participants have their usual visual field test using Humphrey visual field and then visual field test using an iPad. Similar to the traditional Humphrey visual field test, each participant is asked to focus on a red fixation dot and press a button on the keyboard when you see a white spot appear in your side-vision. The software tests each eye separately and takes on average 5 minutes per eye, therefore takes about 10 minutes of testing time.
In order to check if the iPad visual field software is able to produce consistent outcomes on multiple occasions across time, participants are also asked to complete the same iPad visual field test again at the one month, three month and six month visits.
This study does not cause any harm or discomfort to the patient during the test.
Primary outcome measure
1. Accuracy is measured by comparison of visual field Mean Deviation (MD) and Pattern Deviation (PD) produced by Humphrey Visual field and Melbourne Rapid fields app using Pearson correlation statistics at all time points (baseline, 1 month, 3 month and 6 month visit)
2. Inter-sesssion reliability is measured using Blandt-Altman analysis comparing the test outcomes at all time points (baseline, 1 month, 3 month and 6 month visit)
Secondary outcome measures
1. Reliability indices on visual field testing is measured using proportions of Fixation loss, False postive and False negative at all time points (baseine, 1 month, 3 month and 6 month visit)
2. Compliance with test-retest regimen is measured using proportion of visits attended at all time points
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
1. Patients with glaucoma of varying severity (mild, moderate and severe). The eligibility criteria are a diagnosis of glaucoma in one or both eyes (based on characteristic optic disc changes or glaucomatous visual field loss)
2. Visual acuity ≥6/12 vision
3. Aged ≥18 or above
Target number of participants
Participant exclusion criteria
1. Patients with any significant non-glaucomatous conditions affecting visual function such as cataract, macular degeneration, retinal detachment, diabetic retinopathy, non-glaucomatous optic neuropathy
2. Eye surgery less than 3 months prior to recruitment, because testing of visual field shortly after eye surgery can affect test results.
3. Non-English speaking due to the voice prompt on the software is only available in English.
4. Non-elective hospitalization within the past 60 days that could be of concern in the investigator's judgment.
5. Significant non-visual impairment (eg mobility, verbal communication) preventing the completion of the objective.
6. Patients who are not able to provide informed consent.
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Addenbrooke's Cambridge University Hospital
Addenbrooke's Charitable Trust, Cambridge University Hospitals
Addenbrooke's Charitable Trust, Cambridge University Hospitals NHS Foundation Trust, ACT
Funding Body Type
private sector organisation
Funding Body Subtype
Other non-profit organizations
Results and Publications
Publication and dissemination plan
Planned publication in a high-impact peer reviewed journal.
IPD sharing statement:
Clinical information about each patient will also be collected, these include age of patient, treatment history, visual acuity, visual field loss and type of glaucoma (Open angle or close angle or secondary glaucoma). In addition, the visual field testing results obtained from Humphrey Field Analyzer as well as iPad app at all time points (baseline, 1 month, 3 months, and 6 months) will also be stored in the data repository. The results will be de-identified and entered into a database, and will be analysed for significant association.
Consent from participants for data storage is requested as part of the standard informed consent procedure.
Data repository is stored in highly secure local repository provided by Cambridge University HNS Trust. All personnel accessing participant records are required to respect your confidentiality at all times. To ensure privacy, participant's full identity will not appear on any of the study data or samples collected for their analyses. A unique patient number for the study will be used to code any information about the participant. Only principal investigator and authorised personnel will be able to connect this code to the participant, by a list that will be kept securely by the hospital secure data repository for a period of at least 5 years. Study data will be transferred into a computer database and processed to allow the results of this study to be analysed and reported or published. If the results of the study are published, participant identity will remain confidential and de-identified.
Intention to publish date
Participant level data
Stored in repository
Basic results (scientific)