New surgical technique produces better postoperative eye alignment in large angle exotropia
Consecutive exotropia is a manifest exotropia that develops after surgical treatment of esotropia. Many factors are thought to be responsible for this overcorrection, such as amblyopia, presence of A or V patterns, developmental delay, early-onset esotropia, early surgery for esotropia before 6 months of age, and multiple previous strabismus surgeries.
Also, limited adduction is one of the risk factors for consecutive exotropia development caused by early or late muscle slippages, which necessitates medial rectus advancement to be corrected. So, careful assessment of both the medial and lateral rectus muscles during surgical treatment for consecutive exotropia is very important. Permanent treatment of consecutive exotropia depends upon the angle of deviation. Optical treatments like over minus lenses or prescription of prisms are indicated for small deviations less than 20 prism diopters, while surgical correction is usually reserved for larger angle deviations and the surgical plan should be based on the angle of deviations at the time of diagnosis, rather than attempting to undo previous surgery.
Abdelaziz and Ibrahiem designed study to compare the effects of two different procedures: the postoperative eye alignment in patients who underwent bilateral medial rectus advancement with those who underwent unilateral medial rectus advancement plus ipsilateral lateral rectus recession in the case of large angle consecutive exotropia without adduction deficit and its stability in patients with consecutive exotropia after infantile esotropia surgery. Medial rectus advancement combined with ipsilateral lateral rectus recession was more effective than bilateral medial rectus advancement in patients with large angle consecutive exotropia without adduction deficiency.
Thirty-four patients with large angle consecutive exotropia that developed after infantile esotropia surgery were included in this retrospective study. Nineteen patients underwent bilateral medial rectus muscle advancement (group I) and 15 underwent unilateral medial rectus muscle advancement with ipsilateral lateral rectus muscle recession (group II). The follow-up periods were at least 12 months. Postoperative eye alignment was assessed and orthotropia within 10 prism diopters was considered a successful result.
The mean age of patients was 9.45±2.71 years in group I and 9.93±2.05 years in group II. Sixty percent of patients were female in group II and 57.89% in group I. In group I, the mean preoperative angle of deviation was 56.26±3.78 PD at distance and 53.11±3.49 PD at near. In group II, patients had a mean preoperative angle of deviation of 56±3.38 and 52.47±2.77 PD at distance and near, respectively. At the end of the follow-up period, the success rate was 52.63% in group I and 73.33% in group II (p = 0.22). The mean of the dose-effect relationship in group I was 2.62±1.35 PD/mm while in group II it was 2.36±0.84 PD/mm (p = 0.52).
Strabismus surgery reoperations are a complicated issue and must be tailored to the surgeon. Controversy in surgical management of consecutive exotropia does exist. In the current study, all patients underwent bilateral medial rectus muscle recession as a standard procedure to correct infantile esotropia. To manage large angle consecutive exotropia, authors decided to reverse the primary surgery in group I by advancement of the medial rectus muscle guided according to the degree of deviation, while in group II they decided to reverse one medial rectus muscle and recess the previously non-operated lateral rectus muscle of the same eye. At the end of the follow-up period, bilateral medial rectus advancement in group I yielded lower results (52.63%) than unilateral medial rectus advancement plus lateral rectus recession in group II (73.33%), although the difference between the two groups was statistically insignificant (P value = 0.224).
Although this study compared two different surgical techniques conducted by a single surgeon for the management of large angle consecutive exotropia, it has some limitations as it is a retrospective study with a small sample size, so further studies are recommended to overcome the limitations of the current study.
"Medial rectus advancement combined with ipsilateral lateral rectus recession was more effective than bilateral medial rectus advancement in patients with large angle consecutive exotropia without adduction deficiency."
Source: Abdelaziz and Ibrahiem; Clinical Ophthalmology 2022:16
https://doi.org/10.2147/OPTH.S377522
