Lazy Eye

What is a lazy eye?

An amblyopic or lazy eye is one which lacks sharpness due to vision not having developed properly during early childhood. After the first eight to ten years of a child’s life, the visual system is usually fully developed. If, however, during this critical period in the development of a child’s sight there has been a lack of stimulation of the eye, then the nerve pathways responsible for vision are affected and will not recover unless they are treated early.

Generally, amblyopia affects just one eye but it can occasionally affect both.

What are the causes of a lazy eye?

Anything that prevents the eye’s normal development can cause amblyopia. The main causes of amblyopia are:

• Strabismus. One eye wanders, sight is worse in that eye and it doesn’t fully develop.

• Differences in prescriptions between eyes. If there is a difference in nearsightedness, farsightedness or astigmatism between eyes, the eye with the stronger prescription has inferior vision and is at a greater risk of developing amblyopia. Unilateral strabismus is difficult for parents to detect because the child leads an apparently normal life as they can see perfectly with the other eye and the condition goes unnoticed. Therefore, it’s essential for children to regularly see an ophthalmologist.

• Other less frequent but more serious causes include congenital cataracts, corneal lesions, drooping upper eyelid, intraocular tumours and retinal disease.

What are the consequences of lazy eye?

If amblyopia is not treated, it can cause several problems:

• Lazy eye can cause permanent, serious and irreversible visual defects.

• Depth perception (ability to see in three dimensions) can be lost since good vision in both eyes is necessary for good depth perception.

Treatment for lazy eye

The best treatment for lazy eye is prevention and early diagnosis so it’s essential that children regularly see an ophthalmologist. If parents suspect that their child has an eye disease, they should have them checked as soon as possible.

Firstly, the cause of the amblyopia must be treated i.e. recommend the correct eye prescription or operate on a congenital cataract.

Often, despite this treatment, the child’s sight doesn’t improve. In this case, treatment using an eye patch is necessary. When covering the child’s better eye with a patch, they are forced to use and develop their lazy eye. Another similar technique with the same objective is to make vision from the better eye blurry using special eye drops (Atropine). Once sight in the lazy eye has been recovered, it may still be necessary to continue using the eye patch for a few months or years to maintain the improvement.