Incomitant Exotropia After Nasal Polyp Surgery

BACKGROUND: Incomitant exotropia is one of ocular complication that has been reported after intranasal surgery. This case report aims to describe the causes of exotropia in a patient with a history of nasal polyp surgery. CASE PRESENTATION: A 50-years-old male, came with the main complaint of double vision 1 month after nasal polyp surgery. He also complained his right eye turned outward. The visual acuity on the right eye was 6/7.5 with his head turn to the left. On the examination, the Hirschberg test was XT 45°, and the Krimsky test > 95 ∆BI. Duction and version test on the right eye were -4 adduction. There was no shifting on the cover-uncover test. Ishihara test was within normal limit, and there was suppression on the right eye in WFDT. On force generation test, we found limited adduction on the right eye and no restriction in force duction test. Head MRI showed atrophy of medial recti on the right eye, 2.2 mm in size. The patient underwent vertical muscle transposition procedure surgery, and it was found atrophy of medial recti without any rupture. Two months after surgery, the double vision was decreased, the result of the Hirschberg test was XT 30° and Krimsky test 65°∆BI. DISCUSSION: Nasal polyp surgery-related incomitant exotropia mostly caused by extraocular muscles rupture. In this case, we found no rupture. Therefore, we suspected the abnormalities of muscles vascularisation, supported by the atrophy of medial recti.