ICD-10-CM > H00-H59 > H49-H52 > H49 > H49.1 H49.1 Fourth [trochlear] nerve palsy Non-Billable/Non-Specific Codes H49.10Fourth [trochlear] nerve palsy, unspecified eyeH49.11Fourth [trochlear] nerve palsy, right eyeH49.12Fourth [trochlear] nerve palsy, left eyeH49.13Fourth [trochlear] nerve palsy, bilateral