H49.02 Third [oculomotor] nerve palsy, left eye

ICD-10-CM Code H49.02: Third [oculomotor] nerve palsy, left eye

ICD-10-CM code H49.02 identifies third nerve palsy, left eye, a neurologic condition involving dysfunction of the oculomotor nerve. This active, billable diagnosis code is nested under parent concept H49.0. The condition affects eye movements, eyelid elevation, and pupil function, and the code appears in Medicare billing articles. 1 2 4 5

Plain-language overview

Third nerve palsy, also known as oculomotor palsy, results from dysfunction of the third cranial nerve, which controls most eye movements, eyelid elevation, and parasympathetic pupil and lens functions. 2

Dysfunction of the oculomotor nerve produces ophthalmoplegia, ptosis, and variable pupillary involvement, affecting a patient's ability to move the eye, raise the eyelid, and control pupil constriction. 2

What this code represents

ICD-10-CM code H49.02 is the specific diagnosis for third nerve palsy of the left eye, and the terminology record classifies its semantic type as a disease or syndrome. 1

Code H49.02 is a billable, specific code valid for reimbursement, and it is an active concept that has narrower concepts within the ICD-10-CM terminology. 1 5

Coding details

Code H49.02 for left eye palsy is listed alongside H49.03 for bilateral palsy and H49.11 for right eye fourth nerve palsy in a Medicare billing and coding article. 4

Documentation considerations

Clinical documentation for oculomotor palsy may note whether pupillary fibers are spared, as medical causes like diabetes affect blood vessels and spare pupils, while compressive or traumatic injuries cause aberrant nerve regeneration. 2

What the sources add

While the terminology record establishes the official code definition and hierarchy, the clinical reference adds operational context by describing the underlying nerve dysfunction, whereas the Medicare article demonstrates the code's utilization in billing. 1 2 4

Sources

1. ICD-10-CM H49.02 terminology record — National Cancer Institute Enterprise Vocabulary Services; accessed 2026-07-27.
2. Bookshelf — ncbi.nlm.nih.gov; accessed 2026-07-27.
3. EVS Explore — evsexplore.semantics.cancer.gov; accessed 2026-07-27.
4. Article - Billing and Coding: Nerve Conduction Studies and Electromyography (A57123) — cms.gov; accessed 2026-07-27.
5. H49.02 — Third [oculomotor] nerve palsy, left eye | ICD-10 Code · Eleplan — eleplan.com; accessed 2026-07-27.