According to a new study by the University of Waterloo optometrists, elementary school children who read below their grade level may have lower than expected binocular vision test results, even if they see 20/20.
Kids can see words on the page, but if they have difficulty turning their eyes in to read, they may experience symptoms of eye strain, double vision or fatigue after 5 or 10 minutes,” said Dr. Lisa Christian, lead researcher on the project and an Associate Clinical Professor at the School of Optometry and Vision Science. “It’s not just about visual acuity but about how well the eyes work together when performing an activity such as reading.
The Faculty of Science researchers did a retrospective review of 121 children between the ages of 6 and 14 who all had an Individual Education Plan specifically for reading. More than three quarters of the students had good eyesight, but when they were tested for binocular vision, more than a third of the group scored below published norms.
A complete binocular vision assessment is not always part of the standard vision test,” said Christian. “However, binocular vision problems could be compounding a child’s academic difficulties, and should be investigated
Optometrists classify binocular vision anomalies under three main categories: accommodation, vergence and oculomotor - with the symptoms often seeming benign or masking as other problems.
Accommodation is known as eye focusing. Children with accommodative issues have trouble focusing either when they look at near or far, or they may have trouble changing their focus between, for example, a worksheet on their desk (near) and the blackboard (far).
Vergence is known as eye teaming. Children that have trouble with vergence have trouble turning their eyes in (converge) or out (diverge). For example, children with convergence insufficiency have trouble turning their eyes in to read.. This can then lead to symptoms such as fatigue,eye strain, or headaches after as little as 5 or 10 minutes of reading.
Oculomotor is known as eye tracking. Children with these issues may be more likely to lose their place while reading, and often use their finger or a ruler to compensate.
The good news is binocular vision anomalies can be treated with lenses, prisms or vision therapy. In addition, optometrists can provide recommendations to educators to help accommodate students with binocular vision problems. For example, encouraging the use of a line guide while reading, de-cluttering handouts or providing desk copies of notes from board presentations.
Our take home message is it is important for the optometrist to provide a binocular vision assessment in all children, especially those who have been identified with reading problems,” said Christian. “In Ontario, children under 19 are covered for a full eye examination yearly.
The study appeared this month in the Journal of Optometry. Authors also include Dr. Patricia Hrynchak and Dr. Elizabeth Irving, both professors at the School of Optometry and Vision Science, as well as former graduate student Dr. Krithika Nandakumar.