Binocular diplopia can result from injury to or inflammation within the inferior rectus or other muscles after retrobulbar or peribulbar injection for cataract or other ocular surgery. The onset of vertical diplopia immediately following surgery initially suggests nerve damage or myotoxicity from the local anesthetic. Over time, the initial paretic or myotoxic effect evolves into extraocular muscle fibrosis, leading to an overaction or a restricted eye movement pattern. Consecutively, if the inferior rectus muscle is affected, the involved eye transitions from hypertropic (paretic) to hypotropic (restricted) status. In addition, restrictive diplopia may be caused by pterygium excision, scleral buckle placement, episcleral plaque brachytherapy, or tube shunt procedures.
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Excerpted from BCSC 2020-2021 series: Section 5 - Neuro-Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.