الفهرس 
Intermittent Exotropia
Role of defective FusionOnly 14 pages are availabe for public view
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Abstract
Intermittent exotropia is the most common type of exodeviation in children. The child has an X that intermittently breaks down to an XT of one or both eyes, mostly for distance at times of fatigue or inattention. Approximately 80% of X(T) patients will show progressive loss offusional control and an increase in the X(T) over several months to years.
Although X(T) is a common condition, there is still a debate about the efficacy and timing of different treatment options whether surgical or non-surgical, particularly for young children since they are not cooperative for accurate examination. Non-surgical treatment options such as overminus glasses or PTO are used as a primary or a temporizing treatment option in those young children to delay or to improve the sensory outcome after surgery.
Overminus lenses are additional minus power over the cycloplegic refraction. They are prescribed full time with eventual weaning to a point at which the X(T) is well control in the regular refractive correction. It was proved by some authors that they improve control or reduce the angle of the exodeviaton. They work by stimulating the accommodative convergence and thus facilitating fusion.
It has been reported that PTO therapy has potential benefits in preservation of the binocularity and reduction in the frequency and/or magnitude of the exodeviation.
In our study, 60 patients of both sexes with basic or divergence excess types of exodeviation (CI type was excluded) were enrolled from the vicinity of the ophthalmology outpatient clinic of Ain Shams University Hospital. Children were randomly assigned into three groups;overminus spectacles (-3.00 DS over cycloplegic refraction) or PTO therapy (4 hours a day) or observation (non-overminus spectacles if needed or no spectacles) for 4 months followed by 2 months with no treatment.
Of the 60 participants, 78.3% of all the participants completed their 6th month follow up while the 4th-monthfollow-up before treatment cessation was completed by 91.6%.
The mean distance exotropia control score after 4 months of treatment improved significantly in the overminus spectacle and the PTO groups from (3.9 vs. 3.9) to(2.0 vs. 2.7) respectively. After stoppage of treatment for 2 months, the score deteriorated significantly to (3.3 and 3) respectively. The Observation group’s score showed non-significant change all through the study period.
There was a significant improvement in both mean near and distance angles only in the overminus spectacle group after 4 months of treatment and a significant deterioration after 2 months without treatment. Both near and distance angles showed non-significant change in both PTO and observation groups all through the study period.
There was a significant correlation between the poor compliance of the patients and their deterioration especially in the PTO group.
It was concluded that Overminus spectacle therapy is more effective in control of X(T) than PTO therapy. Poor compliance in PTO therapy affects the treatment effectiveness. It’s suggested to work on a protocol of treatment cessation in further studies in a larger sample group.