Keratoconus, unstable, left eye

This code describes a progressive, non-inflammatory corneal ectasia affecting the left eye, where the cornea thins and bulges into a cone-like shape, and the condition is actively worsening. Unstable keratoconus indicates ongoing changes in corneal curvature or thickness, often leading to increasing astigmatism and vision impairment.

Use this code when documentation specifies keratoconus in the left eye with evidence of progression, such as increasing steepening on topography, thinning, or worsening visual acuity despite corrective lenses. This code is appropriate when the clinician explicitly states "unstable" or "progressive" keratoconus for the left eye.

• Ensure laterality is clearly documented as "left eye" to support this specific code.
• Distinguish from stable keratoconus (H18.60-H18.61-) where no progression is noted.
• Look for terms like "progressive," "worsening," or "unstable" in the ophthalmologist's notes.