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Coding for Nervous System Diagnoses – Chapter 7: Diseases of the Eye and Adnexa – PART 3

While codes for the diseases of the eye and adnexa are classified with diseases of the nervous system in Chapter 6 of ICD-9-CM, they are located in their own chapter in ICD-10-CM: Chapter 7- Diseases of the Eye and Adnexa.

As with other codes in ICD-10-CM, codes for diseases of the eye and adnexa have been expanded to increase the anatomic specificity and add the concept of laterality. Many of the diseases in the chapter include codes for right, left, bilateral, and unspecified. If “bilateral” is not an option and the condition is present in both eyes, it is correct to assign two codes, one for the right and one for the left. If, however, there is a code for bilateral, then that code should be assigned, not the codes for right and left. In some cases, as in the coding for blepharitis, the inflammation of eyelash follicles along the edge of the eyelid, the codes are subdivided into right and left, and upper and lower eyelids.

In general, the basic coding guidelines for the medical record documentation include the severity or status of the disease (e.g. acute or chronic), the site, etiology, and any other secondary disease process. If there is a relationship between the condition and the treatment of an eye disorder, the physician must document this cause and effect relationship in the medical record, including whether the complication occurred intraoperatively or postoperatively.

ICD-10-CM provides extensive coding guidelines for glaucoma, the H40 category, that will require a seventh character extension to be assigned for the stage of the disease. The following are available for the seventh character extension:

  • 0 – stage unspecified
  • 1 – Mild stage
  • 2 – Moderate stage
  • 3 – Severe stage
  • 4 – Indeterminate stage

Coding guideline “i.c.7.a.5 Indeterminate Stage Glaucoma” states that the assignment of seventh character 4, indeterminate stage, should be based on the clinical documentation. The character 4 is used for glaucoma when the stage cannot be clinically determined. This seventh character should not be confused with 0 – stage unspecified, which should be assigned when there is no documentation regarding the stage of the glaucoma.

When the patient has bilateral glaucoma and each eye is documented as having the same type of glaucoma and stage of glaucoma, and if there is a bilateral code, report only the one code for the type of glaucoma, bilateral, with the appropriate seventh character for stage of glaucoma. If, however, the classification does not have a code for bilateral glaucoma (i.e. subcategories H40.10, H40.11 and H40.20), report only one code for the type of glaucoma with the appropriate seventh character for the stage.

On the other hand, if the patient presents with glaucoma in both eyes and each is documented as a different stage or type, and the classification distinguishes laterality, assign the appropriate code for each eye rather than the code for bilateral glaucoma. If a patient is admitted with glaucoma and the stage progresses during the admission, assign the code for the highest stage documented.

With a diagnosis of age-related cataract, ICD-10-CM Index directs the coder to Senile Cataract, which is then further specified as right, left, and bilateral. ICD-10-CM includes greater specificity regarding the type and cause of eye disorders which will require thorough documentation by the provider in the medical record.

Knowledge of new, updated, and more specific coding terminology will be needed in addition to more detailed documentation of the patient’s condition. ICD-10-CM now has a number of combination codes that identify both the disorder and common manifestations.

Next week, in Part 4 of this series, we will cover coding guidelines for ICD-10-CM Chapter 8: Diseases of the Ear and Mastoid Process.

Part 1, Coding for Nervous System Diagnoses – ICD-10-CM Compared to ICD-9-CM – PART 1, and Part 2, Coding for Nervous System Diagnoses – Chapter 6: Diseases of the Nervous System – PART 2, also are available for your review.

For more ICD-10 articles, please visit our ICD-10 Updates page.

— Compiled by former CIPROMS ICD-10 Coordinator, Angela Hickman, CPC, CEDC, AHIMA-Approved ICD-10 CM/PCS Trainer, AHIMA Ambassador. All rights reserved. For use or reprint in your blog, website, or publication, please contact us at cipromsmarketing@ciproms.com.


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