The eye turns light from the world around us into electrical signals, but it’s the brain that receives these signals and pieces them together. If someone has trouble seeing, it might indicate a problem with their brain rather than with their visual system. This is cerebral visual impairment (CVI), the diagnosis of which is often missed.

Professor Rachel Pilling, Consultant Paediatric Ophthalmologist, sees children with CVI every day at Bradford Teaching Hospitals NHS Trust. The term CVI affects each child differently and encompasses a range of conditions, and this tends to lead to confusion, she says.

“Each child has a unique combination of difficulties and ways that they use their vision,” she says. Instead of thinking about what a child can see, she tends to think about how they see. Can the child see the object in front of them? If so, can they use their eyes to track it if it moves? And can they use their visual memory to interpret what they’re seeing and to know what to do with it? If the answer to any of these questions is no, that might suggest some form of CVI.”

But if a patient reaches Rachel, they’re one of the lucky ones. Diagnosing CVI is challenging. It is generally accepted that CVI is caused by an injury to the brain that often happens before, during or shortly after birth. Children who are born prematurely or have special educational needs, or conditions such as cerebral palsy, are more at risk of developing CVI (Harwood, 2015). But even if a child is identified as having special educational needs, many of the standard assessments fail to identify CVI, possibly because the symptoms can easily be confused with those of other conditions such as autism spectrum disorder or attention deficit hyperactivity disorder. Someone with CVI might be sensitive to light, struggle with eye contact or appear clumsy – warning signs shared with several other conditions.