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is a manifest outward deviation of the visual axes relative to each other. It may be primary, secondary (associated with poor vision), or consecutive (may follow an ET with time or after surgical correction). According to fusion control, exodeviation could be XT; being present all the time or X (T); ranging according to ease of dissociation, where large X intermittently breaks down to an XT.
X (T) can be further classified into three types based on the difference between the distance and near deviation: (1) basic, where the distance and near deviations are similar, within 10 PD and the target angle is the distance deviation. (2) divergence excess (pseudo and true), where the exotropia is larger for distance fixation than near fixation (≥10 PD). True divergence excess is when the divergence excess persists even after prolonged binocular dissociation by monocular patching (i.e., Patch test). Pseudo-divergence excess is when the near deviation increases after the patch test, so the distance and near deviations are similar (3) convergence insufficiency when the near deviation is 10 PD or larger than the distance deviation. If there is no significant distance deviation, with an exodeviation for near, then this is a pure convergence insufficiency.It is more common in teenagers who report asthenopia.
Surgical treatment is performed to prevent deterioration to constant exotropia, to improve distance stereoacuity and for aesthetic considerations. Common surgical modalities for treatment of XT include BLR and RR procedure.In our study, 30 patients of both sexes with basic type exodeviation were enrolled from the vicinity of the ophthalmology outpatient clinic of Ain Shams University Hospital. Patients were assigned randomly into two groups: group A: 15 patients underwent BLR procedure & group B: 15 patients underwent unilateral RR procedure on the nondominant eye.
It was concluded that in patients with basic type exodeviation with preoperative angle between 25 PD and 35 PD submitted to either BLR or RR, the two procedures could be considered to be equally effective as there are no statistically significant difference between them. Hence, patients’ preference to be operated upon a single eye or both eyes could be the standard of choosing the surgical procedure. In addition, the surgeon’s preference and the consideration of the theoretical complications could affect the decision of which procedure to be performed.
No statistically significant correlation between age, sex or BCVA postoperative outcome.
It was concluded that mean deviations at each postoperative time immediate postoperative deviations did not differ in each group throughout our 6 months follow up.
Overcorrections were seen more with the RR technique than BLR. Undercorrections were seen more with the BLR technique than the RR.
We found that there was no statistically significant difference in overcorrection and undercorrection between both groups.No complications were found in either group in our study.
No lateral incomittance was obsereved in any of our patients.
Further studies could be made to study the long term effect of both techniques. In addition, further research will be necessary to prove the hypothesis that patients who underwent resection procedures under general anesthesia with muscle relaxant tended to be less corrected than patients without muscle relaxant.