Comparison of Lateral Rectus Muscle Re-recession and Medial Rectus Muscle Resection for Treatment of Postoperative Exotropia

Re-surgery for strabismus is one of the most challenging situations in the field of ophthalmology, with profound implications for both the patient and the operating surgeon. The interesting article by Lueder and Galli commendably takes the initiative to discuss this important problem, in particular the management of postoperative exotropia, with a large sample size and a long follow-up period. However, certain observations/queries are in order.

It may be highlighted that the authors have described their findings in the pediatric age group (mean age at first surgery is <4 years). As principles for squint surgery for exotropia in adults are quite different from those in children (including target angle and desired postoperative alignment), the findings cannot be uniformly applied across all age groups.

The authors state that their patients had constant or poorly controlled intermittent exotropia. However, the youngest patient was operated at 8 months of age (age range: 8 months – 7.5 years). It is likely that some of these patients actually had infantile exotropia rather than intermittent exotropia. Also, among patients with intermittent exotropia, there may be basic, convergence insufficiency, divergence excess, and pseudo-divergence excess subtypes. The authors make no comment on these subtypes. This is important, as subtype often determines the muscle to be operated (for example, medial rectus [MR] resection would be preferred in convergence insufficiency). Also, some patients had amblyopia. Surgeons may prefer operating on the worse eye only in such patients and amblyopic eyes may be more susceptible to postoperative exotropia. Also, concurrent cyclovertical procedures (inferior oblique procedures in this study) may affect horizontal alignment and act as confounding factors. Thus, the patient group used is both etiologically and clinically heterogeneous.

Re-surgery on the same muscle is fraught with a lot of problems, especially for the novice surgeon. There may be scar tissue involving the Tenon capsule and the conjunctiva, which may make the surgery technically challenging, with bleeding and obscuration of the operating field. There may also be difficulties in finding, detaching, and reattaching the previously operated muscle, with increased chances of muscle slip and loss. Large recessions require posterior scleral attachment with increased chances of scleral perforation, more so in children. Hang-back recessions may be safer in such cases. Adjustable techniques may also be used. One may also require the use of antimetabolites to decrease inflammation and scarring. It will be interesting to know the difficulties faced by the authors during the procedure.

The conjunctiva may need to be recessed at the end of re-surgery. This brings us to the important question of the type of conjunctival incisions used for the first surgery and re-surgery. The authors describe that some patients undergoing re-recessions also concurrently underwent inferior oblique procedures. Which types of incisions were used in these as well as in the other patients? Was conjunctival recession done?

Supramaximal recessions may cause abduction limitations and palpebral aperture changes. Also, the surgical dosing/calibration tables may no longer be accurate during re-surgery. How were the surgical dosages calculated for re-surgery in this study?

The forced duction test (FDT) for the lateral rectus (LR) may be useful to determine which muscle to operate during re-surgery. If tight, it may indicate that re-recessing the LR may be more useful than resecting the MR. However, the test finds no mention in the present study.

Thus, a number of determinants are important/need to be considered for re-surgery, including age, type and subtype of strabismus, presence of amblyopia, concurrent cyclovertical muscle involvement, FDT, surgical dosage and technique, as well as skill of the operating surgeon. It is both a clinical and an operative challenge to attain desired postoperative alignment and patient satisfaction in such cases.

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Jan 6, 2017 | Posted by in OPHTHALMOLOGY | Comments Off on Comparison of Lateral Rectus Muscle Re-recession and Medial Rectus Muscle Resection for Treatment of Postoperative Exotropia
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