the business of contact lenses

Correct Codes for Contact Lens-Related Infiltrative Keratitis

BY CARLA J. MACK, OD, FAAO

Diagnosis codes help describe the clinical condition and determine the medical necessity for procedures for every patient encounter. Are you confident that you're choosing the most accurate diagnosis codes? Could you locate a code efficiently if and when the need arises?

For some of you, these are straightforward questions with straightforward answers. For others, I know you're trying with a wrinkled brow to remember where you placed the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) reference book for safe keeping. This book as you know provides a comprehensive listing of diagnosis codes issued by the U.S. Department of Health and Human Services with annual revisions made available every October 1st in the latest edition.

Dr. William Miller's Treatment Plan column in the June 2007 issue titled, "Treating Infiltrative Keratitis in Contact Lens Wearers," prompted me to write this column. Finding seemingly common diagnoses isn't always as simple as it may seem. However, if you understand the ICD-9-CM reference guide, this task isn't so difficult.

Once you've definitively diagnosed infiltrative keratitis, you're ready to begin the hunt for the correct code.

Alphabetic or Tabular Listing

The ICD-9-CM book contains an alphabetic section and a numeric section. Fight the urge to go straight to the numeric section and instead, turn first to the alphabetic section. Don't get discouraged when you look up keratitis and see a long list of subheadings and none that corresponds to your diagnosis of infiltrative keratitis.

Next, turn to infiltrate in the alphabetic section. Again, you won't find keratitis as a subheading under infiltrate. You will, however, find corneal as a subheading under infiltrate. A side note or cross-reference directs you to "edema, corneal" where you'll find edema and the corresponding subheading of corneal.

The diagnosis code for corneal edema is 371.20 and is the same code used for corneal infiltrate. Corneal edema is then further differentiated into corneal edema due to contact lenses, 371.24.

You're now ready to double check your accuracy in the numeric or tabular section. It's this code of 371.24 that best describes contact lens-related corneal infiltrates. It would also be appropriate to add superficial keratitis (370.20), punctate keratitis (370.21) or keratoconjunctivitis (370.40) to your diagnosis list.

ICD-9-CM Tips

Here are a few ideas to help you get the most from your ICD-9-CM reference.

• Ensure your practice is equipped with up-to-date reference materials.
• Code definitive diagnoses only and avoid coding for those that are "probable," "suspected" or "rule-out" diagnoses.
• Code patient symptoms when the diagnosis isn't certain.
• Always reference the alphabetic listing first and then the tabular listing to avoid coding errors.
• Diagnosis codes may be 3, 4, or 5 digits; always choose the most specific code that represents your condition.

Look it Up

While this may conjure up images of a scavenger hunt, I encourage you to look up this example and re-familiarize yourself with the ICD-9 code book.

Another code I happened upon that you can use for a number of contact lens-related corneal complications that may not have another, more specific code is 371.82, or corneal disorder due to contact lens (excludes corneal edema due to contact lens). CLS

Dr. Mack is a Diplomate in the Cornea and Contact Lens Section of the American Academy of Optometry and the director of clinics at The Ohio State University College of Optometry.