Developmental Optometry: Going Beyond 20/20

One key to identifying vision problems in developmental optometry is knowing the right questions to ask.

By Kristi Kading, OD, FAAO, FCOVD

Developmental optometry is a subspecialty that concentrates on understanding how a patient’s eyes function, particularly as a team. In a standard pediatric eye examinaton, we look at eye health and clarity of vision, we determine whether a prescription for spectacles is needed, and that is often where the inquiry ends, for both ophthalmologists and optometrists.

In developmental optometry, additional work is performed to examine three factors: how well the eyes coordinate as a team (eye teaming or binocularity), how well the eyes focus at different distances (accommodation), and how well the eyes track (oculomotor function). By assessing those visual skills, we try to understand how the patient functions visually. When there is inefficiency in one or more of those systems in a child, it can have an impact on learning and development, and that is why we use the term developmental optometry.

For this issue of AOC with a series on “Kids in the Exam Chair,” this article explains a bit of what developmental optometrists do, how our exams differ from standard pediatric eye exams, and how we deal with patients and their parents.

REFERRALS

Referrals for developmental optometry examinations come from a number of sources. Often optometrists or ophthalmologists who have done a standard pediatric eye health exam will detect an amblyopia or strabismus or will learn from the parent or patient of a problem with reading or double vision. Other times referrals come from another professional working with a child, such as an occupational therapist or speech language pathologist. Sometimes the parents just find us on their own because they are aware of a problem.

The patient population for developmental optometry can include the entire spectrum of children, not only special needs children. However, it is probably true that those of us who specialize more in this area tend to see more patients with special needs. Some special needs diagnoses are associated with a higher incidence of developmental vision problems: patients with Down syndrome, for example, have a higher incidence of strabismus. Patients with autism can have deficits in any of the functional areas mentioned, so we may see more of these kind of visual inefficiencies in certain populations.

THE EXAM

The nature of the developmental optometric exam can vary depending on the age and level of development of the patient. For any kind of pediatric exam, we have many different tools to try to make the exam fun for the patient and have them maintain interest. Developmental optometry tests can include three-dimensional testing, color vision testing, eye tracking tests, prisms, trial lenses, and other procedures that may be done in the lane but not behind the phoroptor base depending on the needs of the patient.

Oculomotor testing modalities include the King-Devick test, which has been used for more than 30 years to assess reading disabilities. The Developmental Eye Movement Test is a visual-verbal test that looks particularly at reading saccades and helps to evaluate visual processing speed. Visagraph is a test that uses infrared light with special goggles that track each eye as the patient reads a paragraph. It tracks visual skills such as how often patients have to stop, how much information they can take in, how often they have to go back and reread, as well as eye alignment. With a strabismus or an eye coordination problem, this test can show that the left and right eyes are not doing the same thing. The Visagraph also includes a comprehension test at the end with questions about what the patient read (Figure 1). That is very useful for school age kids and even older patients.

Eye teaming or binocularity is assessed by a number of methods, including the Worth four-dot test. This and other clinical tests for assessing stereopsis tell us about the status of the patient’s fusion and suppression. For eye teaming we also look at the range and flexibility of vergences. I usually tell parents this is kind of like a stress test for the visual system. We want to see what happens with fatigue. If there is inefficiency, we want to see where it is breaking down and how much it takes to break it down.

To assess the patient’s ability to accommodate and focus, we use negative and positive relative accommodation as well as facility tests. We use the monocular estimation method, a dynamic retinoscopy procedure that shows where the patient’s accommodative posture is. This test can show if the focusing between the two eyes is asymmetric, which is very common with strabismus or amblyopia. The amblyopic eye tends to focus further back, not on the page, which means the brain is only using one eye. Focusing in front of the page can also be problematic. As we describe it to parents, if you imagine your child reading or looking at a book, you want his or her eyes focusing on the page, not in front or behind it, which can cause blur.

TALKING TO PATIENTS, PARENTS

In our office, we like to have the parents present for the child’s developmental exam because then they can hear what is happening as we look at eye teaming, eye focusing, and eye tracking. What they hear may be that everything looks good, or they may see that we are doing a lot of testing and finding inefficiencies. If it is not possible for at least one parent to be present, then we can give a summary of results at the end.

Figure 1. Visagraph uses infrared light with special goggles that track each eye as the patient reads a paragraph.

I have found that it is helpful for parents to understand certain things in order to appreciate the problems their children may be having. Three things in particular are key to this understanding.

First, one of the big misunderstandings regarding vision among the general public is a very fundamental one: what vision really is. Most people think that vision is 20/20. If you have 20/20 visual acuity, you have good vision (Figure 2).

We all know, however, that good vision is more than 20/20. We do not actually see with our eyes; we see with our brains. When I talk with parents, that is one of the main points I address. Developmental optometry is looking beyond eye health and 20/20 visual acuity. Amblyopia, of course, while it can also affect that 20/20 score, is more than just an eye chart or clarity problem. It’s about how the two eyes work together and how the brain and eyes are connected.

Second, it is typically helpful to show parents a visual aid demonstrating what it looks like when their child is seeing double or out of focus, or when the brain is suppressing one eye. During some of the tests that we perform, we include demonstrations that go a long way toward facilitating the educational process.

The third key is to ask the child to describe what he or she is experiencing. Most kids don’t just come home and say, “Hey, mom, I’m seeing double,” or “One eye is blurry.” When I do these exams with the parents present, if I find something unusual I will ask the patient, “What do the words do when you read?” They may say, “They move around,” or “They kind of go curvy.” And the parents will be sitting there with their mouths dropped open because they have never heard that before.

Just because a child has not described a vision problem that does not mean it has not been happening. Humans are very good at figuring out how to function with whatever visual information is coming in through our eyes. Children generally do not say anything about a vision problem—unless you ask the right questions—because they assume that everybody sees the way they do.

Figure 2. The developmental model of vision shows that vision is more than just 20/20 acuity.

If we are prescribing an extensive treatment plan, especially if we are recommending optometric vision therapy or if there are vision-related learning problems, we typically schedule a separate visit in the office with just the parents. There we talk about the treatment plan and deliver a written report so that the parents have a record of all the tests we did. This is especially helpful if one of the parents has not met us before and been present for the testing. At this meeting they have the opportunity to ask questions, see some demonstrations, and sign off on the treatment plan. This meeting also allows us, as well as the parents, to speak frankly without the child present.

FINAL THOUGHTS

When I write a prescription for a child being evaluated for developmental status, I approach it slightly differently than I would for an adult. The prescription will be based on a number of factors, taking into account how far off the child may be from the developmental norm and if his or her refractive status is amblyogenic. Another consideration is whether a prescription can improve function, for example in a classroom setting. These prescriptions may address any of the functional issues discussed above, whether accommodation, binocularity, strabismus (bifocal or prism), or eye tracking.

In a nutshell, I would say this: the philosophy of prescribing is different in developmental or functional optometry than it is in pediatric or general optometry or ophthalmology.

For colleagues who might want to refer patients for developmental optometry evaluation, a helpful tool is the Convergence Insufficiency Symptom Survey. This is a quick symptoms checklist that the parent or the patient can fill out. Patients with a score higher than the benchmark are good candidates for referral for developmental or binocular vision workup. The nice thing for referring doctors is that they do not have to do any additional tests. They can refer based on symptoms alone, and also the checklist gives us a good idea of what this incoming patient may be experiencing.

A good resource for more information about developmental optometry and all the information discussed in this article is the College of Optometrists in Vision Development (COVD.org). It is an international organization, primarily in the United States and Canada that offers a specialty program so professionals can be board certified in vision development and vision therapy. It also offers continuing education, and it serves as a combination governing board, public awareness resource, and professional resource. n

Kristi Kading, OD, FAAO, FCOVD
• Residency trained and board certified in vision development and vision therapy
• Specialty Eyecare Group, Seattle and Kirkland, Washington
drkristi@specialtyeye.com