Inferior oblique myectomy is a type of strabismus surgical procedure that aims to weaken an extraocular muscle by transecting it. The patient is a four old with a history of inferior oblique overaction and vertical strabismus, which can be corrected by resection of the inferior oblique muscle.
The ointment was applied to the cornea. Forced ductions were performed and identified restriction of the inferior oblique. A conjunctival incision is made in the fornix. Tenon’s capsule is dissected to expose the Inferior Oblique. The inferior oblique muscle is isolated using a Stevens tenotomy hook followed by Jameson muscle hooks. The inferior rectus was identified on a steven’s hook medially to the inferior oblique. The lateral rectus was then identified on a steven’s hook laterally to the inferior oblique. This was done to ensure that neither muscle was incorporated with the portions of the inferior oblique muscle to be cut. Wescott scissors were used to cut both ends of the muscle. Bipolar cautery forceps were used to cauterize the resected proximal and distal ends of the inferior oblique muscle. The two ends were released and the remaining muscle ends were allowed to retract into the orbit. The conjunctiva was closed using a plain gut suture.
No complications arose during the procedure. Postoperatively, the patient had a subconjunctival hemorrhage, injection, and pain that decreased over the following week. Neomycin-polymyxin-dexamethasone drops were applied daily to prevent infection and inflammation. At the one follow-up, the redness and pain had resolved.
Inferior oblique myectomy effectively treats inferior oblique overaction and vertical strabismus associated with this condition.
The ointment was applied to the cornea. Forced ductions were performed and identified restriction of the inferior oblique. A conjunctival incision is made in the fornix. Tenon's capsule is dissected to expose the Inferior Oblique. The inferior oblique muscle is isolated using a Stevens tenotomy hook followed by Jameson muscle hooks. The inferior rectus was identified on a steven’s hook medially to the inferior oblique. The lateral rectus was then identified on a steven’s hook laterally to the inferior oblique. This was done to ensure that neither muscle was incorporated with the portions of the inferior oblique muscle to be cut. Wescott scissors were used to cut both ends of the muscle. Bipolar cautery forceps were used to cauterize the resected proximal and distal ends of the inferior oblique muscle. The two ends were released and the remaining muscle ends were allowed to retract into the orbit. The conjunctiva was closed using a plain gut suture.
Strabismus surgery is indicated when conservative methods, such as the use of eyeglasses, patching, prisms, and orthoptic exercises, can no longer adequately treat a patient’s eye alignment. Common reasons for inferior oblique myectomy include vertical Strabismus, inferior oblique muscle overaction, superior oblique palsy1,2,3,8.
Specific conditions contraindicated for inferior oblique myectomy include asymmetric inferior oblique overaction and non-overactive inferior oblique muscle.
For procedure setup, the patient was positioned supine and placed under general anesthesia. Povidone-iodine was used to disinfect the peri-orbital skin. Sterile drapes were placed over the face and head. An eyelid speculum was placed in the eye. Forced ductions were performed to assess for any restriction of the extraocular muscles.
Strabismus surgery offers both cosmetic and functional benefits of restoring binocular vision and eliminates diplopia and compensatory head postures. Strabismus surgery can correct large deviations that may not be corrected with prisms or eye exercises. Strabismus surgery also leads to more permanent results than botulinum toxin administration4,5. When compared to inferior oblique recession, inferior oblique myectomy has a similar success rate in correcting inferior oblique overaction6.
Risks of strabismus surgery include excessive bleeding, pain, infection, and damage to nearby structures. Intraoperative risks include scarring and globe perforation, but the overall current incidence of globe perforation is low and only rarely associated with serious sequelae7. Other postoperative complications include epithelial inclusion cyst, granuloma, and diplopia, which can be managed with additional procedures. The dissatisfaction with eye alignment can occur, which can be managed with additional procedures or prisms8.
No disclosure of conflicts of interests
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1. DYER JA. Tenotomy of the inferior oblique muscle at its scleral insertion. An easy and effective procedure. Arch Ophthalmol. 1962;68:176-181. doi:10.1001/archopht.1962.00960030180007
2. Squirrell DM, Sears KS, Burke JP. Reexploration and inferior oblique myectomy temporal to the inferior rectus to treat persistent inferior oblique overaction. J AAPOS. 2007;11(1):48-51. doi:10.1016/j.jaapos.2006.09.018
3. Farvardin M, Attarzadeh A. Combined resection and anterior transposition of the inferior oblique muscle for the treatment of moderate to large dissociated vertical deviation associated with inferior oblique muscle overaction. J Pediatr Ophthalmol Strabismus. 2002;39(5):268-294.
4. Helveston EM. Surgical Management of Strabismus. 5th ed. Belgium: Wagenborg; 2005:199.
5. Trumler AA, Robbins SL, Miller AM, et al. Strabismus Surgery, Horizontal. EyeWiki on the American Academy of Ophthalmology website. https://eyewiki.aao.org/Strabismus_Surgery,_Horizontal#Management. Published 2020. Accessed March 2, 2020.
6. Rajavi Z, Molazadeh A, Ramezani A, Yaseri M. A randomized clinical trial comparing myectomy and recession in the management of inferior oblique muscle overaction. J Pediatr Ophthalmol Strabismus. 2011;48(6):375-380. doi:10.3928/01913913-20110118-04
7. Awad AH, Mullaney PB, Al-Hazmi A, et al. Recognized globe perforation during strabismus surgery: incidence, risk factors, and sequelae. J AAPOS. 2000;4(3):150-153.
8. Clark RA, Miller AM, Kozk A, Epley KD, et al. Strabismus Surgery Complications. EyeWiki on the American Academy of Ophthalmology website. https://eyewiki.aao.org/w/index.php?
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Review Inferior Oblique Myectomy.