“Lazy Eye” means, that the visual acuity of that eye/s is less than normal because of reduced maturation due to several reasons. Just by looking at a child or adult it is not possible to say if that person is suffering from a lazy eye. A squinting eye may be a lazy eye. A child with properly aligned eyes, may still be suffering from a lazy eye.

 

 

How does a lazy eye develop?  What exactly is a lazy eye?

 

Vision is no different to other functions e.g. speaking / walking. The newborn’s eye is a small eye and initially the newborn cannot see a sharp picture. With time, the baby learns how to use the internal muscles of the eye to focus the picture in front of him. When the picture is properly focused, the baby starts to learn how to fixate (and fuse) the two pictures (from the right and left eyes) together. Hence in the very early months of a baby’s life one may notice that the eyes may at times become misaligned - the baby has not yet learned how to fuse the two pictures yet. By the age of 4 months this function should be properly developed and the eyes should be straight. Normal vision develops when the child learns how to see with both eyes equally. So, vision too, is also a learning process.

 

If something inhibits the child from using both eyes equally then the child may develop a lazy eye. If for some reason, the child is not seeing as good from one eye as he does from his other eye then the child will learn to use only his good eye and his brain “forgets” the image from his other eye with the consequence that the eye becomes lazy. Some causes for a lazy eye are:

• If something is preventing his eye from seeing properly e.g. a lens opacity or an upper lid which is drooping and blocking vision and not allowing that eye to see.

• A defect of vision, e.g. the child may be long-sighted (hyperope) or short-sighted (myope) or astigmatic. Sometimes a combination of these defects may exist;

• A squint, this is when one eye deviates inwards (towards the nose) or outwards (towards the ear). Other deviations are also possible. The squint may be large angle, which is obvious, or small angle which can only be picked up by proper examination and is not visible to the naked eye, we call the latter a micro squint. It is important to mention that the smaller the squint angle, the higher the risk of getting a lazy eye!!

 

When, for any of the above reasons, the child is not “using” an eye as much as the other, or because of an unfocused image on one or both eyes, that eye/s may be “switched off” by the brain and a lazy eye/s develop/s. The peripheral vision often remains good. The earlier we find out and tackle such problems, the better are the chances for a positive outcome.

 

 

When is the best time to have my child’s eyes examined?

 

Unless you are aware of a positive family history, every child, between the ages of 2 and 3 years should have their first eye examination. Naturally, if you notice that something is “not right” with your child’s eyes, no matter how old the child is, then this should be brought to immediate medical attention and it would be best to speak about this with your paediatrician. He / She will be able to give further advice.

 

 

 

What should I consider?

 

Things to bear in mind are the family history of both parents’. This includes squints, lazy eyes, visual problems i.e. long sightedness / short sightedness / astigmatism / large differences of spectacle correction between the eyes, these should be discussed with the paediatrician. In such cases the child should be examined at the age of 1 year.

 

Information stating that the first examination should be carried out between the ages of 4 and 5 years is wrong. We should, in this day and age, aim for preventive medicine and not curative medicine. If certain conditions are found out early then we may be in a position of preventing a lazy eye from developing. If caught too late and a lazy eye has set in then we have the task, sometimes difficult, of trying to improve the lazy eye.

 

 

How common is a lazy eye?

 

The incidence of a lazy eye is quoted as 3 - 12% of children worldwide, but this depends from country to country. In Malta it is about 6%.

 

 

How will I find out if my child is suffering from a lazy eye? The examination.

 

The paediatrician may carry out some tests. If doubt exists the child must be seen by an ophthalmologist.

 

The tests carried out depend on the child’s age. The first information comes from the parents and their observation of the child. The doctor observes

• the alignment;

• if the child is “looking” with both eyes together;

• if he is able to follow a target;

• vision tests, depending on age;

• the existence of any errors of vision, e.g. long-sighted, short-sighted, +/- astigmatic. Eyedrops to relax the internal muscle of the eye will be used for this test.

 

 

How will the doctor treat a lazy eye?

 

Any refractive errors (defects of vison) are corrected. Prescribed glasses should be used during all waking hours. Upon reassessment it may be decided to start with occlusion exercises or other methods may be used.

 

Occlusion exercises are trying for both child and parent. The time and effort which parents’ invest during this stage is of utmost importance because the time-window available is very restricted. Once over we are not given a second chance of trying. Strict monitoring by parent and doctor is required during these exercises.

 

As everything in life, lazy eyes come in different degrees of severity. Whilst, not treating a lazy eye does not mean that sight of that eye will be lost, it does have implications for adult life. It is documented that people with one good eye have a three-fold chance of seriously injuring their “good” eye during adult life. Due to various medical conditions vision in an eye may diminish or be lost. If an eye with 20% vision can be improved to 80% vision, loss of the “good” eye through some form of accident or disease means that that person will now use the lazy eye with 80% rather than 20% vision for the rest of his life.

 

 

When should treatment for a lazy eye start?

 

The simple answer to this question is - as early as possible. The earlier we detect and the earlier we start the higher are our chances of success. OF IMPORTANT NOTE, here we must again mention that the treatment-window of a lazy eye is limited. The chances of improving a lazy eye after the age of 8 / 9 years are very slim. There are controversies whether one should try after this age. If we start early (preventive) and preclude a lazy eye from developing it would be far better than having to treat when the lazy eye has set in. Not every treated child will attain 100% acuity but, as mentioned earlier, if an eye which initially had 20% vision can be improved to 60% that is a 40% gain!

 

Whilst trying does not give a 100% guarantee of success, not trying is a guarantee for failure to improve.