A18.52 Tuberculous keratitis

Name of the Condition

• Tuberculous keratitis
• ICD Code: A18.52

Summary

Tuberculous keratitis is a rare form of extrapulmonary tuberculosis where Mycobacterium tuberculosis infects the cornea, the clear front surface of the eye. This condition occurs when TB bacteria spread from a primary site, typically the lungs, to the cornea via the bloodstream or lymphatic system. It can cause inflammation, pain, and vision impairment if not promptly diagnosed and treated.

Causes

Tuberculous keratitis is caused by the dissemination of Mycobacterium tuberculosis from an existing infection, usually pulmonary tuberculosis. The bacteria can travel to the cornea during active disease or reactivation of latent TB. Direct inoculation is rare but possible in certain cases.

Risk Factors

• Immunocompromised states, such as HIV/AIDS or chronic immunosuppressive therapy.
• History of untreated or inadequately treated tuberculosis.
• Close contact with individuals who have active TB.
• Living in or traveling to regions with high TB prevalence.
• Underlying conditions like diabetes or malnutrition.

Symptoms

• Redness and swelling in the eye.
• Eye pain and sensitivity to light (photophobia).
• Decreased vision or blurred vision.
• Discharge or tearing.
• Corneal opacity or ulceration.

Diagnosis

Diagnosis involves a comprehensive eye examination, including slit-lamp evaluation to assess corneal changes. Laboratory tests, such as corneal scrapings for acid-fast bacilli or PCR, may confirm TB infection. Imaging or systemic evaluation may be performed to identify the primary TB source.

Treatment Options

Treatment typically includes systemic antitubercular therapy (e.g., isoniazid, rifampin) to target the underlying infection. Topical medications, such as corticosteroids or antibiotics, may be used to manage inflammation or secondary infections. Close monitoring by an ophthalmologist is essential.

Prognosis and Follow-Up

With timely and appropriate treatment, prognosis is generally favorable, though vision impairment may occur if the cornea is severely damaged. Follow-up care includes regular eye exams to monitor healing and address complications like scarring or vision loss.

Complications

• Corneal scarring or opacity.
• Vision loss or blindness.
• Secondary bacterial or fungal infections.
• Chronic inflammation leading to persistent discomfort.

Lifestyle & Prevention

• Avoid close contact with individuals who have active TB.
• Ensure proper ventilation in living or work environments.
• Maintain good overall health to support immune function.
• Seek prompt treatment for suspected TB infections.

When to Seek Professional Help

Consult an ophthalmologist immediately if you experience persistent eye pain, redness, vision changes, or discharge, especially if you have a history of TB or risk factors for the disease.

Tips for Medical Coders

Use A18.52 for tuberculous keratitis, specifying the corneal involvement. Document clinical findings (e.g., corneal ulceration, inflammation) and confirmatory tests (e.g., acid-fast bacilli, PCR) to support the diagnosis. Ensure the code aligns with the specific site of infection and any associated complications.