For Orthoptists & Ophthalmologists

ASTEROID publication in the Journal of Vision

The first paper on the findings from the ASTEROID project has been published in the Journal of Vision. It is free to view and download from the Journal of Vision website.

The paper, entitled: "Avoiding monocular artifacts in clinical stereotests presented on column-interleaved digital stereoscopic displays", explains how we designed the test so as to avoid giving “monocular artefacts” which could enable patients to perform the test even if they didn’t have good stereopsis.

Prof Ignacio Serrano Pedraza from Complutense University of Madrid who has been the Psychophysics consultant for ASTEROID was the lead author, working with Jenny and Kathleen to undertake this research.



Tell us what you would like to see from our test

 

 

Assessing binocular vision


“A measurement of stereoacuity (3D vision) is considered the ‘gold standard’” for assessing binocular vision.”  - 
Cochrane review on interventions for infantile esotropia (Elliott & Shafiq, 2013)


Every year, there are half a million appointments where children come into NHS eye clinics to be diagnosed or treated for binocular vision disorders. As part of this, the ophthalmologist will want to assess their binocular function, to find out how well their two eyes work with each other and with the brain. The “gold standard” for doing this is to test their stereoacuity.

 

 

 

Current clinical stereotests


The problem is that the majority of tests can be difficult in small children. They can be boring, so it’s hard to tell whether a child has stopped responding because they’ve genuinely reached their limit, or simply because they’ve lost interest.

Being printed on card or perspex, they offer only a limited number of depth steps, so they aren't always accurate. They can also be quite unreliable – the reported value can fluctuate within a factor of 4 just because of measurement error (this was shown in a paper whose lead author was Wendy Adams, now a consultant at Sunderland). Fairly often, the child just won’t cooperate at all.

 

Why this matters

 

“…worrying lack of evidence ... pressing need for improved measures of severity….” Cochrane review on interventions for intermittent exotropia (Hatt & Gnanaraj, 2013)

Unfortunately, this leave ophthalmologists making clinical judgments based on noisy or inaccurate data. And remember, we’re talking about clinical judgments such as when or whether to operate on a child’s eyes – there are more than 6000 such operations on the NHS every year. So it’s important that the evidence base supporting these interventions is adequate.

 

Solution

 

Mobile devices have become available which can present glasses-free 3D. We want to use this to embed a stereotest within a fun, engaging game. Kids love playing games on these things - as you’ll know if you’ve ever tried to wrestle your iPad back from a toddler.

They’ll be giving their answers by touching the screen. We’ll be able to let them hold the tablet, because the front camera will automatically monitor how far away they are holding the device and calibrate the data accordingly. Because these devices are smart computers, we’ll be able to use all the same clever algorithms which have been developed over decades in vision science labs.