Patients with high myopia may sometimes develop a very significant convergent squint which is not only cosmetic disfiguring but severely affect the vision. The mechanism is thought to be herniation of the globe outside the muscle cone usually between the superior and lateral rectus (as mentioned in previous post). Surgical correction is often complex as simple recession/resection technique is usually insufficient to significantly correct the malposition. One way of correcting this difficult squint is with muscle transposition. However, it is important to inform the patients that more than one operation may be needed for good outcome.
Surgical procedure showing transposition of muscles for myopic strabismus fixus.
The medial rectus was released and allowed to hang back by 8mm. a. The superior
rectus is isolated; b. the superior rectus is split into two equal halves; c. the lateral rectus
is isolated and split into two equal halves; d e and f. a 5/0 silk is used to tie the upper
half of the rectus at 15mm from its origin of insertion to the lateral half
of the superior rectus. The technique strengthen the lateral rectus
and push the globe back into the muscle cone.
Diagramtic presentation of the procedure shown in the photos.
This patient has residual convergent squint but is able to perform
her daily activities without help.
Despite the located lenses due to high myopia, this patient regains good vision after
the surgery while awaiting surgical removal of the dropped lenses.
This patient has residual hypotropia but is pleased with his appearance.