Third [oculomotor] nerve palsy, left eye

This code describes a dysfunction of the third cranial nerve affecting the left eye. This nerve is responsible for controlling most eye movements, elevating the eyelid, and constricting the pupil. Palsy of this nerve can lead to ptosis, diplopia, and an inability to move the left eye in certain directions.

Use this code when documentation clearly indicates a diagnosis of third cranial nerve palsy specifically affecting the left eye. This diagnosis is typically supported by neurological examination findings demonstrating impaired adduction, elevation, and depression of the left eye, along with potential ptosis and pupillary involvement.

• Ensure laterality is precisely documented (left eye) to avoid miscoding.
• Distinguish from other cranial nerve palsies, particularly abducens (CN VI) or trochlear (CN IV) nerve palsies, which affect different eye movements.
• If the cause of the palsy is known (e.g., aneurysm, diabetes), code the underlying condition first, followed by this code.