Grading Versus Classic Inferior Oblique Anterior Transposition in Patient With Asymmetric Dissociated Vertical Deviation

Purpose: To determine the surgical outcomes of the grading versus classic Inferior Oblique Anterior Transposition (IOAT) technique in treatment of patients with asymmetric dissociated vertical deviation (DVD) and inferior oblique overaction (IOOA).

Methods: In this randomized clinical trial, a total of 38 patients with IOOA of >+1 and a minimum DVD difference of 5pd between their two eyes will be included. Comprehensive ophthalmic examinations including visual acuity assessment, measurements of noncyclo- and cycloplegic refraction as well as ocular deviation, biomicroscopic and funduscopic evaluation will be performed at baseline and repeated three months after the surgery. The function of extra ocular muscles will be evaluated by duction and version movements denoting from -4 (underaction) to +4 (overaction) grades. Also, IOOA will be graded as +1 to +4 according to the covering of the cornea under the superior eyelid during the ocular movement towards supra-nasal direction. The difference of DVD≥5pd between two eyes will be considered as asymmetric DVD. All patients will be randomized in the two groups to undergo IOAT surgical procedure; in the classic group, IO muscle will be sutured to the sclera at the level of inferior rectus (IR) insertion at its temporal border, without considering the asymmetric DVD between the two eyes; while in the grading group, IO muscle of the eye with more severe DVD will be sutured at the level of IR insertion and IO muscle of the eye with lower magnitude of DVD will be sutured 2mm posterior to the sclera to consider the preoperative DVD difference between the two eyes.