Outcome of surgical treatment of monocular elevation deficiency

To assess the outcome of surgical treatment in patients with monocular elevation deficiency.

This prospective study included 36 patients of monocular elevation deficiency surgically treated from January 2006 to June 2009, at a tertiary care eye hospital in Rawalpindi, Pakistan. Corrected visual acuity, refractive error, ocular examination, orthoptic assessment and ptosis evaluation were recorded. Strabismus surgery was performed according to the results of forced duction test (FDT). Ptosis surgery, if required, was performed after the strabismus surgery. Patients having any restrictive cause or previous strabismus surgery were excluded. The study conformed to all local laws and was compliant with the principles of the Declaration of Helsinki and had the approval of the Hospital Ethics Committee.

The 36 patients were treated surgically and completed the required follow-up. The forced duction test was positive for inferior rectus (IR) of the involved eye in 20 of the 36 eyes (55.55%). Twelve patients had inferior rectus recession with or without one horizontal muscle recession or resection, 12 had Knapp procedure correcting for any horizontal deviation if present, 10 had inferior rectus recession followed by Knapp surgery, with or without recession or resection of horizontal recti, 1 patient had horizontal correction only, while one patient had ptosis correction only without squint surgery. Of the 36 patients, 33 had post-operative (PO) hypotropia within 10 prism diopters (PD). Three patients developed consecutive hypertropia.

Careful pre-operative evaluation can lead to satisfactory cosmetic improvement after surgery in monocular elevation deficiency. The forced duction test should be performed in both eyes so that any associated oblique muscle laxity (OML) can be noted.