29th December 2023

Skew deviation

This is a vertical and oblique diplopia which cannot be localised to a single extraocular muscle or cranial nerve and is, therefore, a diagnosis of exclusion. Suspicion for skew deviation should be raised if a 3-step test does not highlight a problem with the 4th cranial nerve, i.e. the problematic muscle is not superior oblique. Further testing can be performed via Maddox Rod; however, this requires specialist input and interpretation.