Examining small children – guide for optometrists

Young children are not able to describe their vision or explain their visual symptoms, so there is a bigger emphasis on observing them and taking their birth and health history from their parents or guardians. Standard questions include those about any immediate concerns and the cause of the appointment. It may be that the parents have noticed something unusual, or the child’s nursery has mentioned something to them.

You may ask about any complications during pregnancy and the child’s delivery, their birth weight and whether they were born full-term as well as about the child’s motor development for which vision plays a fundamental role.

Another set of assessment questions usually relates to any family history of ocular disease, whether any close family members or the child have had eye problems, treatments, surgeries, allergies, systemic diseases affecting eye health and if the child is taking any medication.

It is important to observe the child while taking their history. Is there any asymmetry in in their face? Is there difference in the opening of the eyes? Is one side of the face or the head flatter than the other? Do they tilt their head when looking around? These could indicate eye problems. Does their behaviour correspond with the reported symptoms? For example, if the child says they can’t see, does their behaviour support that or are they happily play on their mother’s phone whilst waiting?

The child’s functional vision is evaluated using a series of tests to establish their responses to visual stimuli. The results are then compared to the expected functional vision for children of the same age and abilities.

Infants 6 months to 2 years of age are usually tested for general visual behaviour and responses and if there is any degree of ocular misalignment. It’s important to try to make the process quick and fun to keep the child’s attention.

The tests would assess:

• Pupil responses - measures the child’s reflex that regulates the pupil’s constriction and dilation in reaction to light, usually a pen torch.
• Fixate and follow - evaluates the child’s ability to fixate on and follow an object as it moves. The fixation skill usually develops by 6 weeks old, while the ability to follow an object typically develops by three months of age. For this test, a small, silent toy is held in front of the child’s eyes. The trick is to get the child look at the toy and then follow it with their eyes as it’s moved to various positions around them. Horizontal tracking develops first so test this as standard. If the test indicates poor ability to fix and follow an object, refer the child to a consultant for further investigations.
• Red (fundus) reflex – while the red reflex eye test is commonly performed shortly after birth as part of the newborn screening process, it may also be conducted during routine child eye check-ups to check for potential abnormalities in the eyes, such as cataracts, retinoblastoma, or other eye conditions that may affect vision. The test should be conducted in a dark room to dilate the pupils and enhance the visibility of the red reflex. An ophthalmoscope is used to emit a light that is shone into the baby’s eyes. The red reflex in both eyes should be symmetrical and of equal brightness. If any concerns or abnormalities are noted during the red reflex test, an urgent referral to an eye specialist is needed.
• Ocular misalignment – using cover/uncover test to identify the presence and type of ocular deviation. The child looks straight ahead at the toy or other object while their eyes are briefly covered one at a time. Observe any movement in the other (uncovered) eye. Such movement may be abnormal and may indicate strabismus.
• Retinoscopy - to measure any refractive error such as myopia, that might be affecting a child’s vision. While it may be difficult to do it on very young patients, the best practice is to assess children of all ages where possible. Young children should have their eyes dilated for the test. During the test, the child is asked to look at a picture or a light, while the optometrist shines the retinoscope into the eyes and then move it in different directions to assess the reflection (retinoscopic reflex) from the child’s eyes and find the point at which the light focuses or “neutralizes.”
  Different lenses should be placed in front of the child’s eyes to refine the
  results and determine the most accurate prescription.
• Visual acuity – testing visual acuity in small children is challenging. Preferential looking cards, containing striped patterns or images of different spatial frequency, can be used in infants if available. As children tend to prefer looking at patterns with higher spatial frequency (thinner stripes, more detail), the examiner can estimate the visual acuity based on the thinnest stripes the child responds to. It’s important to note that the preferential tests provide estimates of acuity and results may be influenced by the child’s mood and interest. Visual behaviour can be used to estimate vision in babies if preferential looking cards are not practical or available. Does the baby look at faces or objects? Do they respond to smiles or behaviour? Do they watch what is happening around them? Children with better vision in one eye will object or cry when the better eye is covered and this is a useful observation to note.

Visual acuity in older pre-school children can be tested with Kay’s pictures or letters, and school age children can usually manage a Snellen or LogMar test. Eyes should be tested together and individually, if possible, to identify reduced vision which may indicate a refractive error.

Regular eye exams from young age and a subsequent referral to secondary care as needed, are essential for detecting and addressing visual problems in children. In general, the younger the child, the more urgent the referral should be. If a glasses prescription is found in association with reduced vision, always give the glasses, even if a referral is made. The sooner the child starts wearing the glasses, the sooner their visual rehabilitation can begin.