In partial oculomotor nerve palsy, the involved muscles are paretic to varying degrees. This variability in residual muscle function defines the pattern of strabismus and determines which surgical steps remain necessary when an initial intervention is insufficient.
The first surgical line — resection of the paretic muscle with residual function combined with recession of its antagonist (in the horizontal and vertical planes) — targeted improved primary position alignment with restoration of a functional field of binocular single vision. When those goals are not achieved, a structured next-line approach is indicated.
The next stage addresses residual vertical and torsional deviation through transposition and torsional surgery. The specific surgical configuration is guided by the residual function of the affected muscles and the nature of the remaining deviation — the full protocol details which procedures apply under which conditions.
DOI: 10.1016/j.jaapos.2022.11.017
With partial oculomotor nerve palsy, the involved muscles are paretic to varying degrees.
When there is residual function of one or both vertical rectus muscles, nasal transposition of these muscles may be used in place of nasal transposition of the SO, or instead of NTSLR.
If elevation is limited, transposition of the MR and LR toward the SR can be considered if the IR is not tight on forced duction testing; if it is, and active force generation testing suggests residual activity of the SR, IR recession may be preferable.
Generally, incyclotorsion is present due to preserved SO tone, and SO-weakening procedures are performed if torsional diplopia is a concern.
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