Diffuse interstitial keratitis, bilateral

This code describes a chronic, non-ulcerative inflammation affecting the middle layers of both corneas, characterized by cellular infiltration without primary involvement of the epithelium or endothelium. It often presents with photophobia, pain, and decreased vision due to corneal opacification. This condition can be a manifestation of systemic diseases like syphilis, tuberculosis, or Lyme disease, or it can be idiopathic.

Use this code when documentation clearly indicates diffuse interstitial keratitis affecting both eyes. This diagnosis is typically supported by slit-lamp examination findings showing stromal inflammation, neovascularization, and corneal edema. It is appropriate when the laterality is explicitly stated as bilateral, or when documentation implies involvement of both eyes without specifying laterality (as bilateral is the most specific option for unspecified laterality in this context).

• Ensure the documentation specifies "diffuse" and "interstitial" to differentiate from other forms of keratitis.
• Always check for an underlying systemic cause, and code it first if identified and actively treated.
• Do not use this code for localized or non-interstitial forms of keratitis; specific codes exist for those conditions.