A Comparison of Squint Tests
Research type
Research Study
Full title
A comparison of the traditional Hess chart, a projector-based Lancaster test, and VR headset-based Lancaster test in the assessment of ocular deviation
IRAS ID
209165
Contact name
Peter Thomas
Contact email
Sponsor organisation
Cambridge University Hospitals NHS Foundation Trust
Duration of Study in the UK
0 years, 4 months, 1 days
Research summary
Strabismus, or squint, describes any misalignment of the eyes, and can affect both children and adults. As a result, the images of the outside world conveyed to the brain from the two eyes do not correspond, which can result in diplopia, or ‘double vision’. As well as impacting on a patient’s functionality, strabismus can have cosmetic and psychosocial ramifications. Furthermore, if left untreated in childhood, strabismus can lead to life-long visual impairment, despite best spectacle correction.
Current treatment is guided by the exact nature of the strabismus and the patient’s age; options include spectacle prescription to correct underlying refractive error, use of prisms to control deviation, or in certain cases, surgery. In order to investigate the type of strabismus present, and determine the best management, tests of ocular deviation are performed in Eye Clinics.
The aim of these tests is to ‘dissociate’ the eyes, and thus establish how each eye is working individually. The Hess chart and the Lancaster red-green test are two well-established tests of ocular deviation in clinical practice, which use red-green goggles to dissociate the eyes, and change the image that each eye receives. They are able to produce reproducible, pictorial representations of deviations of the eye to aid in management of strabismus.
However, both of these tests require a screen to be mounted onto the wall, upon which lights are projected, and the patient to be sat at the appropriate distance from the screen without moving their head for the duration of the test. In this study, we investigate whether a virtual reality headset-based Lancaster red-green test can produce comparable measurements of ocular deviation to the traditional Hess chart and Lancaster red-green test, without the need for a screen or projector, or control of head posture.
Lay Summary of Results:
This small feasibility study investigated whether a virtual reality headset could be used to assess ocular misalignment, also known as strabismus or squint. In routine eye clinics, patients with double vision or abnormal eye movements may undergo tests such as the Lees screen, Hess chart or Lancaster red-green test. These tests help clinicians understand which eye muscles are affected and guide diagnosis and management.
The study compared a virtual reality headset-based test with established clinical tests of ocular misalignment. Three adult patients with different causes of abnormal eye movement took part. Each patient underwent routine clinical assessment and a virtual reality-based test. The virtual reality test presented separate images to each eye through the headset and measured horizontal, vertical and torsional deviation.
The results showed that the pattern of eye movement abnormality measured using the virtual reality headset was broadly consistent with the pattern obtained using the standard Lees screen test. Agreement was seen in patients with a fourth nerve palsy, thyroid eye disease and comitant esotropia.
The study was very small and was designed only to assess feasibility, not to prove that the virtual reality test should replace existing clinical tests. The findings suggested that virtual reality headsets could potentially provide a practical way to assess ocular misalignment without the need for a fixed wall-mounted screen or strict head fixation. Further larger studies would be needed to assess accuracy, reliability, patient acceptability and clinical usefulness.
The results were published in the peer-reviewed journal Eye in 2017: Nesaratnam N, Thomas P, Vivian A. Stepping into the virtual unknown: feasibility study of a virtual reality-based test of ocular misalignment. Eye. 2017;31:1503–1506.
Has the registry been updated to include summary results?: No
If yes - please enter the URL to summary results:
If no – why not?: N/A
Did you follow your dissemination plan submitted in the IRAS application form (Q A51)?: Yes
If yes, describe or provide URLs to disseminated materials: This was publised in Eye in 2017:
https://gbr01.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftrack.pstmrk.it%2F3ts%2Fwww.nature.com%252Farticles%252Feye201797%2FNBTI%2FD9XFAQ%2FAQ%2Fb6c4028f-387c-4a8f-b86c-8ed51ccb94f0%2F1%2FgBi08W1BJB&data=05%7C02%7Cleedswest.rec%40hra.nhs.uk%7C3b8079fcdbfc4ce79e4f08dec2e7d336%7C8e1f0acad87d4f20939e36243d574267%7C0%7C0%7C639162498101314419%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=SAOnja0bbidNVSFP5gMxcdcCjcXuxGprdJVbWHoBnKg%3D&reserved=0
If pending, date when dissemination is expected:
If no, explain why you didn't follow it:
Have participants been informed of the results of the study?: No
If yes, describe and/or provide URLs to materials shared and how they were shared:
If pending, date when feedback is expected:
If no, explain why they haven't: No.This was a small single-site feasibility study undertaken in 2016/2017. The approved IRAS application stated that participants would be asked at enrolment whether they wished to receive the study results, and that those who elected to do so would be contacted after study conclusion.
The final report is being submitted retrospectively after identifying that administrative close-out had not been completed at the time. I have checked with the other member of the research team who; neither of us not recall any participants requesting to receive the results, and do not think individual participant notification was undertaken. The study results were disseminated publicly through peer-reviewed publication in Eye in 2017.
Have you enabled sharing of study data with others?: No
If yes, describe or provide URLs to how it has been shared:
If no, explain why sharing hasn't been enabled: Results were published as above with meaningful data included in the figures.
Have you enabled sharing of tissue samples and associated data with others?: No
If yes, describe or provide a URL:
If no, explain why: N/A
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Yorkshire & The Humber - Leeds West Research Ethics Committee
REC reference
16/YH/0378
Date of REC Opinion
1 Sep 2016
REC opinion
Favourable Opinion