Ophthalmology and Optometry Coding Alert

Question: What is the proper ICD-9 code for pellucid marginal degeneration?

Pennsylvania Subscriber

Answer: Use 371.40 (Corneal degeneration, unspecified) to correctly code for pellucid marginal degeneration cases.

Pellucid marginal degeneration is a subtle condition that could lead to corneal ectasia following laser eye surgery. Although the condition is atypical and rare, clinicians should learn how to identify pellucid and screen patients for it preoperatively.

In pellucid marginal degeneration, corneal thinning typically occurs from the 4 to the 8 o'clock position approximately 1 mm from the inferior limbus. Another difference between pellucid marginal degeneration and keratoconus is that the onset of pellucid tends to be in patients aged in their 30s, rather than around the time of puberty.

The key to recognizing early cases of pellucid is topography. Patients may appear clinically normal and have normal pachymetry, if it is performed centrally or paracentrally. However, since the cornea typically gets thicker from the center to the periphery, clinicians should be suspicious if there is little difference between the central and inferior pachymetry.