The Mechanics of Lazy Eye

Eye patches are frequently used to treat children with lazy eye.
Lazy Eye (or Amblyopia) is a visual impairment that occurs in early childhood, well before school age. In this condition, visual acuity does not develop evenly in both of a child’s eyes, and the brain begins to ignore visual information from the weaker, “lazy” eye. Approximately three percent of Canadian children experience this condition. Although vision in the weaker eye may be aided with eyeglasses, eyeglasses will not correct the communication between the eye and the brain. Currently an eye patch over the stronger eye is the gold standard treatment to improve eye-brain communication; however up to 50% of children do not have a complete restoration of visual acuity with this therapy. When amblyopia is not successfully treated in early life, abnormal vision may persist throughout life.

Dr. Agnes Wong and her team are working to better understand how and why amblyopia occurs and its effects on hand-eye coordination and depth perception. This information will contribute to improved rehabilitation for lazy eye. 

Dr. Wong and her team were the first group to show that patients with lazy eye have impaired perception of images in real-world settings and that the condition has a detrimental effect on how a person’s vision guides her/his movements. The team has developed a virtual reality apparatus that lets them conduct detailed studies of how a person moves their eyes and limbs in response to what they see.

The team is also helping to explain how lazy eye influences the processing of visual signals. Human eyes make quick binocularly co-ordinated movements call saccades, which help the brain build a high resolution picture of a scene by moving the eyes to specific areas of interest. Dr. Wong’s team has demonstrated that children with lazy eye have abnormal saccades.

Dr. Wong’s research is support by grants from the Canadian Foundation for Innovation and the Canadian Institutes of Health Research.