Homonymous bilateral field defects, left side

This code describes a specific type of visual field defect where there is a loss of the left half of the visual field in both eyes. This defect is "homonymous" because the same side of the visual field is affected in each eye, and it is "bilateral" because both eyes are involved. It typically results from a lesion in the retrochiasmal visual pathway, such as a stroke or tumor affecting the right optic tract or visual cortex.

Use this code when documentation clearly indicates a homonymous bilateral field defect affecting the left side of the visual field. This diagnosis is often made following a neurological examination and visual field testing (e.g., perimetry). Supporting documentation should specify the laterality and homonymous nature of the visual field loss.

• Ensure the documentation specifies "left side" for the homonymous defect; do not confuse with right-sided defects.
• Distinguish from other visual field defects, such as bitemporal hemianopsia or quadrantanopsia.
• Always code the underlying cause of the visual field defect (e.g., stroke, tumor) first, if known and documented.