It is important to detect and treat a lazy eye or amblyopia as soon as possible, preferably before a child is six years old. Treatment is essential if normal vision in the “bad” eye is going to be restored. If the condition is left untreated, central vision in the weak eye may never fully develop.
Not all children may be aware of their symptoms if they have amblyopia. While older children may notice their sight is poor in one eye, younger children are usually either unaware or unable to explain that there vision is less clear in one eye. All children should have their eyes tested before they start school and every two years thereafter in order to check for visual abnormalities.
A form of the condition called refractive amblyopia (refer to “Amblyopia types” for details) is often the most challenging to detect early on, as the eye may appear to be looking ahead even though the brain is no longer interpreting images from it.
Detection and diagnosis
An amblyopia diagnosis is usually made by an eye specialist or an ophthalmologist. During an eye test, the structure and appearance of the eyes are checked. Visual acuity checks are performed for each individual eye.
Other tests include:
- For young children, one technique is to place a hand over each of the child’s eyes, one at a time. If the child pushes the hand away when it is over one eye but not the other, one eye may be working less well.
- For an older child that can talk, the Snellen chart (with rows of letters or numbers) may be used.
The ophthalmologist also checks the eyes for other conditions such as squint, cataracts and ptosis (dropping eyelid) as these conditions can cause amblyopia.
Treatment of lazy eye
Treatment for amblyopia is more effective, the earlier it is started. There are two main approaches to treatment which include correcting any underlying pathology causing the condition and encouraging the child to use the weak eye again.
Glasses are prescribed to correct problems such as refractive errors, astigmatism and squint but the child must wear the glasses continuously. For older children, contact lenses may be suggested. Surgical therapy may be useful in cases of cataract and ptosis.
To encourage a child to use the weaker eye, the “good” eye may be covered with an eye patch. The length of time the child has to spend wearing the patch depends on their age and the intensity of the problem. A patch is most effective if the child starts wearing it before the age of eight. An alternative to wearing an eye patch is using eye drops to temporarily blur vision in the good eye, therefore forcing the child to use the “bad” eye.
Reviewed by Sally Robertson, BSc