It’s important to first understand how normal vision works before moving on to the definition of anisometropia. Light from the outside world passes through the various parts of the eye, namely the cornea, lens and vitreous, to finally strike the retina at the back of the eye.

The retina converts the light into an electrochemical signal, which is sent to the brain. The brain then interprets this signal as a clear image.If the light does not focus on the retina precisely, the message that the brain translates, creates a blurred picture. This is known as a refractive error.

This error, or degree of blurriness, can be measured in each eye. Glasses can then be prescribed to counteract this error.The refractive error in each eye can be different, in other words, the degree of blurriness in each eye can actually differ! This is known as “anisometropia”.

Did you know that treatment and diagnosis can lead to the prevention of permanent vision loss?

1. Simple: When only one eye is affected;
2. Compound: When both eyes are affected in the same way;
3. Mixed: When both eyes have a refractive error, but one is short-sighted, and the other is long-sighted.

Remember that your child should be screened at: birth, 6 months and just before attending school.

This protocol is designed to identify problems with vision, especially in infants and in children who are still too young to describe their symptoms clearly.

If your child is at an age where they can verbalize their symptoms, they may complain of double vision (diplopia), headaches, nausea, tired eyes, dizziness and sensitivity to light.

One of the most common complications of anisometropia in infants is amblyopia. When the eyes refract unequally, a fuzzy image is created in the brain. To limit the confusion, the brain starts to favour the stronger eye by gradually “switching off” the signals from the weaker eye. If not identified and treated promptly, this eye could be permanently “turned off” (amblyopia) by the brain, resulting in blindness.

Amblyopia can be difficult to identify in your child because the condition doesn’t have any external signs. It is also more common in pre-verbal children making the process even trickier. Some clues that amblyopia may be present include, watching your baby’s behavior when one eye is covered, noticing that your baby cries continuously and observing that your child constantly bumps into objects.

The final sign of anisometropia that you might notice is a squint, either intermittent or permanent.

The treatment has a high success rate, especially if treated early enough.

Prompt and accurate diagnosis is essential and in the case of amblyopia, will aim to prevent permanent vision loss.

An ophthalmologist will conduct a thorough examination to make a diagnosis. A treatment plan will be created to address your child’s specific needs.