How do optometrists obtain information without a child answering “which option is better, one or two?”
Dr. Leanne Roach
It was easy for me to choose a topic for my first blog post with Insight Optometry. Since beginning practicing with the team in July 2016, I have made some amazing connections with patients of all ages. My patients with children often ask whether their child is even old enough for an eye exam, given a significant amount of time is spent choosing which option is clearest. Surely, they express, young children cannot definitively answer which option is clearer! With children, optometrists rely on objective measurements that do not require such answers.
So, is your child old enough for an eye exam? The answer is always…YES! Below are some techniques we employ in paediatric eye exams:
Determining visual acuity
Visual acuity, or the sharpness of vision, is measured typically by patients reciting letters on an eye chart. When toddlers have not yet learned their letters, we use shapes and symbols that the child can either name or match with a card they hold on their lap. With infants, we present a card with alternating black and white stripes simultaneously with a grey coloured card. The infant will look at the stripes, as it appears more interesting to them (this is called preferential looking). The gratings get closer together with each presentation in order to arrive at a visual acuity limit. No matter the method used, testing visual acuity involves the child wearing a pirate patch so we can measure each eye individually. If your child is apprehensive with objects around their face, we recommend “playing pirate” at home with a patch before the exam date so the experience will be more familiar to the child.
Assessing ocular alignment
Normal ocular alignment occurs when both eyes are pointed straight ahead and work as a team to achieve binocular vision. When strabismus (an eye turn) is suspected, we use prism lenses to determine the magnitude while the child is focusing on an object, usually a toy or a picture of an animal. Furthermore, we measure stereopsis, or 3-D vision, by having the child wear a pair of special glasses and name or match the shapes seen on the cards. Correct results on this test indicate that their eyes are working together as a team.
Typical colour vision testing involves naming shapes or numbers displayed on various backgrounds. With children, we often ask them to trace the pattern they see with a paintbrush or point to the card with a specific object, for example, a circle, when two cards are presented side by side. We can confidently determine colour vision around age 4 or 5.
While the child is looking straight ahead at us or an interesting toy, we are able to “sneak” other toys, sometimes with the help of our assistants, behind them and slowly bring them to the side of their vision. When we see the child quickly look to the object on the side, we know they caught a glimpse of it in their peripheral vision.
Determining a glasses prescription
The best way to determine a child’s prescription is through cycloplegic retinoscopy. Under “cycloplegia”, the child’s focusing system is completely relaxed. We achieve this by administering dilation drops that will cause the child’s pupils to enlarge and vision to be blurry for a while thereafter. We then use our retinoscope to determine if the child has a glasses prescription. By shining the retinoscope light towards the eye and holding up different lenses in front of the light beam, we are able to measure how the light refracts or focuses and whether a prescription is required, all without asking the child which option seems clearest. Children usually love this part of the exam as we commonly ask them to focus on Rescue Heroes or Dora the Explorer on DVD while we take our measurements.
Assessing ocular health
Depending on the comfort level of the child, we will use various handheld or head-mounted tools to assess ocular health. With focusing lenses, we can evaluate structures in the back of the eye including the optic nerve, macula, and peripheral retina. Thankfully, serious eye conditions causing blindness in children are rare, but an ocular health assessment is still extremely important. We always recommend a optomap retinal image as well, so comparisons can be easily made in the future.
In summary, paediatric eye exams are extremely important and useful information is obtained at any age. By using a variety of techniques (and toys!), we are accurately able to assess your child’s visual function and eye health. We are looking forward to meeting your child at his or her first eye exam!