"I’ve just seen two images of the same person on the TV screen," my aging mother complained years ago. She had developed double vision.
But what causes double vision? And how many children suffering from attention deficit hyperactive disorder — or ADHD — are being needlessly medicated when the trouble is in their eye?
Dr. Patrick Quaid, an expert in double vision, is head of the Guelph Vision Therapy Centre. He says double vision must be taken seriously as a diagnosis can range from brain tumour, concussion, inflammation of an artery, to simple dysfunction of ocular muscles.
Fortunately, when adults notice double vision, they know something is wrong that demands quick attention.
But Quaid says children with ADHD often get either a delayed diagnosis or no diagnosis of ocular disorder. In addition, doctors treating a child with ADHD rarely consider arranging for an eye examination to detect ocular malfunction.
The most commonly encountered abnormality is "convergence insufficiency," or difficulty keeping the eyes tuned when reading. These children have eyes that do not work in unison due to an imbalance of muscle control.
Consequently, they see double when reading, frequently lose their place, find reading frustrating and shy away from it, which affects their learning. They’re also inclined to rub their eyes and suffer from frontal headaches that are misdiagnosed as sinusitis or migraine.
A major trap can lead both parents and doctors astray. Quaid states that ironically, parents of children with convergence insufficiency may be told their child has 20/20 vision by a regular eye test.
Yet the child still sees double when trying to focus on things that are close. The disconnect is that children may not complain. Although their vision is abnormal, it is, to them, their normal vision.
Convergence insufficiency is not rare. Quaid claims that one in 10 people has some sort of eye teaming problem.
But what is shocking, and generally unknown, is that children affected with ADHD have three times greater risk of convergence insufficiency. All the more reason that these children must see an eye doctor who is cognizant of eye teaming abnormalities.
Quaid adds that doctors who are looking for a quick fix often place ADHD children on Ritalin, or some other attention medication, without arranging for a detailed oculomotor workup. This is like putting a blanket over a fire and hoping it will go out.
During an interview, Quaid discussed another pressing problem that concerns many parents — post-trauma vision syndrome. Today, brain concussions are becoming a fact of life for children and adults involved in contact sports. Moreover, bruised brains can result in serious neurological and ocular abnormalities despite normal results from MRI and CT scans.
Ahead of the times, Quaid has sage advice for those who intend to engage in contact sports — be sure to get a baseline test for binocular vision function first.
This is important as those who already have binocular vision dysfunction, and may not realize it, will likely suffer even greater eye teaming issues should they suffer a subsequent concussion. In fact, a concussion may be like the straw that breaks the camel’s back, causing more severe and less treatable problems.
Just how many children in this country are being diagnosed with ADHD when they in fact suffer from subtle forms of double vision is unknown. But we do know that too many children are being placed on Ritalin for questionable reasons. Surely it makes sense to arrange for an eye examination specifically looking at eye teaming skills before doing so.
The difficulty for parents is that children will usually not complain of problems with eye teaming, as they may not be aware of what to report. This may result in misdiagnosis.
Fortunately, the Guelph Vision Therapy Centre is one of the few places that offers a comprehensive approach to ADHD and eye teaming problems. This involves close interaction among eye doctors with experience in binocular vision disorders, psychologists, speech and language pathologists and occupational therapists.
For more information, parents should see the excellent College of Optometrists Vision Development website at covd.org.
» Dr. Gifford-Jones is a graduate of The University of Toronto and The Harvard Medical School. He took post-graduate training in surgery at the Strong Memorial Hospital in Rochester, McGill University in Montreal and Harvard. During his medical training he has been a family doctor, hotel doctor and ship’s surgeon. His medical column is published by 70 Canadian newspapers, several in the U.S. and the Epoch Times which has editions in a number of European countries.