Improving the eyesight of children using a tablet computer

Professor Steven Dakin
University of Auckland

What is the problem and who does it affect?

Amblyopia, colloquially referred to as ‘lazy eye’, is a developmental disorder characterised by reduced vision in one eye. It is the most common cause of visual impairment in childhood, affecting one in 30 children.

Long-term functional consequences of amblyopia are poor acuity (sharpness of sight) and contrast sensitivity, reduced or absent stereo-vision (depth perception) and elevated crowding, all in the affected eye.

The treatment of amblyopia using occlusion therapy – covering of the better-seeing eye – is well established, and can effectively reduce the risk of bilateral visual impairment later in life. Consequently, early detection is paramount.

Currently children are screened for amblyopia and other vision problems at around 4 years of age with a test that involves matching letters in the distance. However, this test has a high false positive referral rate meaning that many children who are ‘normal’ are also referred for a full eye examination.

 

What is the research hoping to achieve?

This research proposes to develop a new, tablet-computer based screening test for use in schools. This test is intended to be affordable, simple, quick to administer and engaging for children. The goal is to make the test as specific as possible; to pick up amblyopia and only amblyopia, as early as possible.

Traditionally amblyopia has been considered a monocular condition, characterised by reduced sharpness of sight in one eye. Recent studies, however, suggest that it is a binocular condition resulting from the brain’s inability to combine the images of the two eyes. This leads to inter-ocular suppression – the child relies heavily on the better-seeing eye and effectively “ignores” the affected eye, since using only one eye gives better vision than both eyes together.

The new screening test will include measures of suppression, depth perception and a shaped-based vision test. The goal is to more accurately detect children with ‘lazy eye’, which will allow these children to get quick and effective treatment. Because the system makes multiple measures of vision, the test may reduce the number of ‘normal’ children who are unnecessarily referred for further assessment.