Overview
Inherited retinal dystrophy is an important cause of childhood blindness. It’s the name for a group of conditions that affect the light-sensitive photoreceptor cells in the retina, including Leber congenital amaurosis and Stargardt macular dystrophy.
Clinical trials for gene therapy to treat inherited retinal dystrophy are taking place at Moorfields and elsewhere. A vital part of evaluating new treatments is having reliable measures of how the retina is working. But this is difficult to do with children. Infants can’t necessarily follow the instructions and older children may have trouble staying focussed.
In this project Dr Nardini is developing new ways to measure vision in children that are quick and reliable. The tests will measure several aspects of vision including how clear it is and how well photoreceptors are working. They will make use of technology such as touch screens for responses and eye-tracking to measure where the child is looking automatically.
The new tests will be calibrated by testing children with good vision and the team can use the results to study patterns of sight loss in young patients. Results from the study with make it easier to assess the benefits of treatment for children with inherited sight loss.
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Publications
- Burton, E. Infant Visual Assessment: Using Eye Tracking to Measure Visual Acuity. (2012).
- Jones, P. R., Kalwarowsky, S., Braddick, O. J., Atkinson, J. & Nardini, M. Optimizing the rapid measurement of detection thresholds in infants. Journal of Vision 15, 2 (2015).
- Bainbridge, J. W. B. et al. Long-Term Effect of Gene Therapy on Leber’s Congenital Amaurosis. New England Journal of Medicine 372, 1887–1897 (2015).
- Jones, P. R., Kalwarowsky, S., Atkinson, J., Braddick, O. J. & Nardini, M. Automated Measurement of Resolution Acuity in Infants Using Remote Eye-Tracking. Investigative Ophthalmology & Visual Science 55, 8102–8110 (2014).
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Research update
The team has developed new measures using technology including remote eye-tracking, in which participants look at items on a screen, and a computer and eye-tracker automatically score where they look From this the team can work out which items the children could or could not see. This is particularly suitable for infants who can’t talk yet.
The researchers have shown that these new methods work, including via publications in peer-reviewed scientific journals. The tests have also contributed to ongoing clinical trials such as the RPE65 gene therapy trial at Moorfields.
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Scientific summary
Understanding the developmental course of retinal dystrophies: from genes to behaviour
Inherited retinal dystrophies are an important cause of childhood blindness. The genetic mutations underlying many dystrophies are now known, and trials for gene replacement therapy are underway at Moorfields Eye Hospital and elsewhere. Understanding the natural history of these disorders, and evaluating any treatment, crucially depends on obtaining reliable measures of retinal function in young children. In this project we propose to develop and validate new age-appropriate behavioural (psychophysical) tests of retinal function for children and infants. These tests will measure (1) visual acuity and contrast sensitivity, (2) sensitivity across the visual field, and (3) photoreceptor function. These tests will take advantage of new technology (e.g. eye tracking and touch-screen interfaces) to maximise their speed and reliability. These new tests will be used to characterise in detail the visual consequences of retinal dystrophies in childhood, relating these to structural changes evident in retinal imaging and to the underlying genetic mutation. The tests will also be used to evaluate the outcome of current and future trials of novel therapies in young patients.