Incidence of Strabismus Post–Plaque Brachytherapy in Patients With Uveal Melanoma

Abstract

PurposeTo determine the incidence and type of strabismus in patients with uveal melanoma treated with plaque brachytherapy. DesignRetrospective incidence estimation study SettingMulticenter Patient Population438 eyes of 438 patients with uveal melanoma treated with plaque brachytherapy between October 2011 to May 2021. InterventionIodine 125 plaque brachytherapy Main Outcome MeasuresVariables reviewed included incidence of non-resolving strabismus post-plaque brachytherapy, type of strabismus developed, extraocular muscles operated, and modality of treatment received. ResultsFour hundred thirty-eight patients underwent plaque brachytherapy treatment for uveal melanoma. Eleven patients developed strabismus post plaque brachytherapy (2.5%, n=11/438). Of these patients, five (1.1%, n=5/438) developed strabismus immediately post-operation. Specifically, two patients (0.5%, n=2/438) developed strabismus immediately post-operation due to slipped muscles, two patients (0.5%, n=2/438) due to decompensated phorias, and one patient (0.5%, n=1/438) due to a fibrotic muscle. Six patients (1.4%, n=6/438) developed late onset sensory strabismus. A total of 355 (81.1%, n=355/438) patients had their extraocular muscles disinserted during surgery, with the lateral rectus being the most common, accounting for 45.4% (n=161/355). Followed by the superior rectus at 26.8% (n=95/355). Strabismus surgery was the most common treatment modality, comprising 72.7% (n=8/11) of patients. ConclusionThe incidence of strabismus following plaque brachytherapy treatment for uveal melanoma was low, and primarily classified as late onset sensory strabismus. Previous studies may underestimate the long-term incidence of strabismus post plaque brachytherapy by focusing primarily on strabismus present immediately post-operatively.