Children’s eye care is often overlooked, with parents assuming that the checks done at school are enough to ensure all is well. Whilst school screening is a worthwhile exercise, it can mean that children are 5+ before they receive their first check. This is really too old- we are born with quite poor vision, and this gradually improves until it should be at a near adult like level by an age of three. Children need to learn to use their eyes as a single unit, and anything that causes an interruption to this can have lifelong effects.
We recommend the first eye examination should be done at approximately 3 years of age- this is particularly important where there is any family history of squints or lazy eyes, but a child of any age can be checked, and should be checked if there is any concern.
To book an appointment contact us, or ask your GP for a referral to the children’s community clinic for your area- there will be a waiting list, but the length depends on your local clinic.
The most common childhood eye problem, except for simple refractive errors, is amblyopia (dull sight through lack of use).
If a person develops a squint (a turn or a cast) in an eye, they have a problem. Two eyes pointing in different directions, means that the individual loses their sense of what is straight ahead- the object they are looking at may be straight in front of them, but one eye tells the brain “straight ahead” whilst the other says something different, depending on whether the squinting eye is in, out, up or down- this causes confusion.
Double vision also occurs- one eye is looking at an object, but the other eye is looking at something else, so the brain sees two of everything (and because of confusion it can’t tell which is in the straight ahead position).
An adult will generally have to cover one eye to get around this problem, but children quickly adapt to this by suppressing an eye. Suppression is a normal phenomenon- the brain cannot process all of the information it receives, so it prioritises- a car alarm going off for example- initially we are aware of it, but soon become unaware, until it stops, at which point we may often think to ourselves “has that just stopped?” “or when did that stop?”. The answer is probably right now, but we become aware that we were unaware of something- suppressing it. Suppression allows us to have a conversation in a crowded room, and we have all been in the situation where another conversation, perhaps behind us is more interesting than the one we are having, resulting in that classic “sorry, what were you saying?” line.
Children can quickly learn to suppress an eye, to avoid the double vision and confusion caused, but soon this can become habit- when the good eye is covered, the brain doesn’t want to use the other eye- it forgets how to! Most children end up favouring one eye, and suppressing the other, which then becomes the squinting eye, and probably also becomes lazy. Some can learn to alternate- they do not develop a preference for either eye, so one eye looks straight and the other is turned. Because the suppression also alternates this group are the only ones who are unlikely to develop a lazy eye.
The primary problem is the squint, and this may be correctable with spectacles- most squints arise because the child is Hyperopic -longsighted, and without correction has to focus the eyes to see clearly. Because the focussing ability is there to adjust from far to near, the eyes automatically want to converge when they focus, and this can lead to an inward turning eye. Some squints may be correctable surgically, but only those which cannot be fully corrected with glasses would be candidates- the cause of the squint must be determined. Whether correctable by either means the effect of the lazy eye must be addressed, most commonly by patching the good eye to force the brain to use the bad one.
Amblyopia can also occur when one eye sees better than the other- for example due to a refractive error (Longsight), or rarer due to a cataract or a droopy eyelid. If the individual can see better with one eye than they could with both, again it will not take long for the child to learn to ignore the bad eye, which again can quickly become habitual.
Physical causes of poor sight in one eye- such as congenital cataract or a droopy lid (ptosis) must be corrected as soon after birth as possible as these cases cause the most severe types of amblyopia- instead of the child having to learn to ignore an eye, they just never learn to use it, which is much more difficult to remedy with patching.
Many adults present for routine eye tests with a lazy eye and a history of patching as a child, but say that it didn’t work- because their eye is still lazy. Without patching however the eye may have been much worse, and patching cannot be expected to bring the poor eye all the way back up to the same level as the good one- there is a risk that too much patching could affect the good eye, and no-one wants to achieve equal vision by pulling the good eye down to match the bad one! Any child on patch therapy must be regularly monitored to ensure this does not occur. The amount of patching is determined by the severity of amblyopia, the age at detection and by charting the improvement over time- a young child’s lazy eye usually improves quite rapidly initially and then begins to slow, eventually reaching a plateau, which is a sign that further patching would not be a benefit. A lazy eye detected after age 7 is probably not going to improve very much at all, because at this age the visual system is fully developed.
Nobody is too old to get an improvement with patching, but with increasing age comes a requirement for longer periods of wearing the patch, which most would find impractical. Most adults also admit to poor compliance with patching as a child- taking it off as soon as out of sight of their parents! This is understandable- many children cannot comprehend why the grown ups want to make them walk about with a cover over their good eye so that they can’t see very well- quite an incentive to cheat!
Any parent who had eye problems as a child would be advised to have their children checked as young as possible, as many causes of amblyopia are hereditary.
It is not possible to test very young children to the same level of accuracy we could achieve with an adult, but this is not important- what the Optometrist needs to determine is, firstly, is there a squint or significant risk of squint and secondly, is there a significant refractive error in one or both eyes which may impede normal development. We can then go on to check for normal eye control and binocular visual development, by checking the child’s stereoscopic (3D) vision.
3D vision requires that both eyes are seeing approximately equally well, and are being used as a pair, which can confirm that everything is developing normally. Ideally the Optometrists would also want to measure the standard of vision of the child, and there are ways of doing this easily even on pre-school children- nobody needs to know letters to have an eye exam!
From then routine checks are advisable to ensure everything stays on track- we would generally recommend 6 monthly checkups for a young child with no visual problems or risks.