Amblyopia, or “Lazy Eye”
The condition commonly known as “lazy eye” is actually called amblyopia. Affecting approximately 2-3% of children, it’s the most common reason why children and younger adults may experience decreased vision in a single eye. It rarely occurs in both eyes at once.
Amblyopia is the result of a disconnect in the signals between the brain and one of the eyes. The eye appears normal, but it’s not functioning properly. It can wander inward or outward, whilst the brain is favouring the other eye – hence the term “lazy eye”. There are several reasons this can happen, and most of them are to do with the eye not developing properly during childhood – specifically, the ability to focus light on the retina.
A retina that is working properly converts light into impulses that travel up the optic nerve to the brain, shaping the images that we see. With amblyopia, however, the affected eye is unable to focus light correctly, whether from near-sightedness, far-sightedness, or astigmatism (a misshaping of the cornea, the eye’s lens).
Treating “lazy eye” in children
Because the brain will favour the eye that is functioning correctly, the best treatment for children is to strengthen the amblyopic eye. This involves taking the stronger eye out of the mix for a while – which is why the best treatment for this condition is a simple eye patch.
Children’s eyes are still developing into the late teens and early twenties, so the earlier amblyopia can be diagnosed and treated, the better the chances that vision can be improved, both in the eye itself and the part of the brain that processes vision. Adhering to the eye patch therapy for a period of a few weeks to a few months, depending on the advice of your ophthalmologist can be very effective.
Another option is to try using eye drops called atropine in the stronger eye, causing blurred vision for a short period of time. The principle is the same as with the eye patch: forcing the amblyopic eye to work harder for a couple of hours each day, by reducing vision in the “good” eye. Some parents may find it easier to get children to take the drops than to wear the patch, but be assured that either approach is just as effective.
There is not much evidence yet surrounding the success of treatment plans for amblyopia in adults. With the visual system still developing in childhood, particularly up to the ages of seven to ten, it’s still considered the best time to diagnose “lazy eye” and begin treatments.
That’s why it’s so important to monitor children’s visual development, even if there’s no evidence of a problem – bearing in mind that an amblyopic eye can appear “normal”. One helpful exercise you can try at home is to ask your child to cover each eye in turn, and try reading or drawing using just one eye. If the child struggles with one but not the other, talk to your eye doctor, if you have one, or to your GP or paediatrician, who can refer you to a qualified eye doctor.