H31.23 Gyrate atrophy, choroid

Name of the Condition

• Gyrate Atrophy, Choroid (ICD Code: H31.23)

Summary

Gyrate atrophy of the choroid is a rare, inherited disorder characterized by progressive degeneration of the choroid and retinal pigment epithelium, leading to vision loss. It involves the gradual atrophy of these structures, resulting in impaired visual function over time.

Causes

The condition is primarily caused by mutations in the OAT gene, which is involved in the metabolism of ornithine. This genetic defect disrupts normal metabolic processes, leading to the accumulation of ornithine and subsequent degeneration of the choroid and retina.

Risk Factors

• Family history of gyrate atrophy.
• Genetic mutations in the OAT gene.
• Consanguinity (increased risk in populations with shared ancestry).

Symptoms

• Progressive night blindness (nyctalopia).
• Loss of peripheral vision (tunnel vision).
• Decreased visual acuity over time.
• Difficulty with color perception in advanced stages.
• Photophobia (sensitivity to light).

Diagnosis

Diagnosis involves a comprehensive eye examination, including dilated fundus evaluation to assess retinal and choroidal changes. Additional tests may include optical coherence tomography (OCT) to visualize retinal layers, electroretinography (ERG) to measure retinal function, and genetic testing to confirm OAT gene mutations. Elevated plasma ornithine levels may also be measured to support the diagnosis.

Treatment Options

While no cure exists, treatments aim to manage symptoms and may include:

• Dietary restriction of arginine and protein to reduce ornithine levels.
• Vitamin B6 (pyridoxine) supplementation, which may help lower ornithine in some patients.
• Low vision aids to assist with daily activities.
• Regular monitoring of visual function and metabolic status.

Prognosis and Follow-Up

Prognosis varies, with most patients experiencing progressive vision loss over time. Regular follow-up with an ophthalmologist is essential to monitor disease progression, adjust treatments, and address complications. Early intervention may help slow visual decline in some cases.

Complications

• Progressive vision loss leading to legal blindness.
• Cataracts (may develop secondary to retinal degeneration).
• Macular involvement, which can further impair central vision.

Lifestyle & Prevention

• Adherence to dietary restrictions (low-arginine diet) as recommended by a healthcare provider.
• Use of protective eyewear to reduce photophobia.
• Regular eye examinations to detect changes early.

When to Seek Professional Help

Seek immediate medical attention if you experience sudden changes in vision, increased difficulty with night vision, or new visual disturbances. Prompt evaluation is important for managing symptoms and preventing further progression.

Tips for Medical Coders

When coding for gyrate atrophy, ensure documentation supports the diagnosis, including clinical findings (e.g., fundus changes, visual field defects) and genetic testing results if available. Note that this code is specific to the choroidal form of the condition and should not be used for other retinal dystrophies. Verify that the code aligns with the patient's documented clinical presentation and any associated metabolic abnormalities.