EXOTROPIA

 

This handout largely refers to the intermittent exotropia that is seen in children and adolescents. In these patients there is an underlying tendency for the eyes to diverge outwards (probably because of the anatomical arrangement of the muscles and other orbital tissues). This is controlled to varying degrees by the patient.

The symptoms that are noticed are an outswing of one or both eye(s), intermittent tendency to close the out-turning eye (squinting) and intermittent double vision.

The normal expectations vary. Many cases gradually deteriorate with time. The duration of each episode of out-turning increases and then the frequency of these episodes increases. Eventually the angle of out-turning increases. Not all cases get worse and a small number of cases may spontaneously get better (especially very young children) as the orbital tissues grow and change.

Sometimes glasses are an issue, especially if there is poor focusing in just one eye or one eye is slightly lazy.

In general, the most reliable treatment is surgery. The threshold for contemplating surgery should include one or more of the following:

1. I think my child often looks a bit weird because of the eye condition.
2. Others notice that my child often looks a bit weird.
3. My child has bothersome double vision.

Other therapies such as exercises, patching and glasses are always worth trying once the above measured threshold has been reached. Glasses are usually the most effective; the glasses are usually optically "wrong" and are used to change the aim of the eyes by modifying the focus. This approach is typically used for kids under 10. It is sometimes a useful delaying technique that allows us to defer surgery until the age of 6 or 7 (there are some small theoretical advantages to delaying surgery).

Once the decision has been made to consider surgery, the patient needs a separate visit for a pre-operative examination using techniques (e.g. wearing a patch for an hour) that try and simulate the "maximum" degree of outward deviation present. At this pre-operative assessment we are able to show that 1 in 10 children may require bifocals at some stage.

In the first week or two after surgery intermittent cross-eyedness with intermittent double vision is frequent. Of patients who have surgery, approximately 80% have a good result at 12 months and there is a low "deterioration" rate beyond that.

Repeat surgeries are needed in about 10% of patients in the first year after surgery, and about another 10% over the next 10 years. Few patients need repeat surgery beyond that time.