Lateral rectus muscle entrapment, left eye

This code signifies the involuntary restriction or impingement of the left lateral rectus muscle, which is responsible for abducting (moving outward) the left eye. This entrapment typically results from trauma, such as an orbital fracture, or can be iatrogenic following surgery. It leads to impaired ocular motility and diplopia.

Assign this code when documentation clearly indicates mechanical restriction of the left lateral rectus muscle, often due to tissue or bone impinging on the muscle. This diagnosis is typically supported by imaging studies (e.g., CT scan of the orbit) showing the entrapment and clinical findings of restricted abduction and diplopia of the left eye.

• Ensure laterality is precisely documented and matches the code (left eye).
• Distinguish from paresis or paralysis (H49.xx) where the muscle itself is weak or non-functional, rather than physically restricted.
• Code any underlying cause, such as an orbital fracture (S02.1xx), as a primary diagnosis if applicable, with this code as a secondary diagnosis.