Ischemic optic neuropathy, left eye

This code signifies damage to the left optic nerve due to insufficient blood supply, leading to sudden, painless vision loss in that eye. This condition results from an interruption of blood flow to the optic nerve head, causing nerve fiber death.

Assign this code when documentation clearly indicates ischemic optic neuropathy affecting the left eye. Supporting documentation should include ophthalmological examination findings, visual field defects, and often, a history of cardiovascular risk factors or giant cell arteritis.

• Ensure laterality is precisely documented; do not use for bilateral or unspecified cases.
• Distinguish from optic neuritis (H46.-) which is inflammatory, not ischemic.
• Code any underlying systemic conditions, such as giant cell arteritis (M31.5) or diabetes mellitus, as additional diagnoses.