Acute retinal necrosis

Acute Retinal Necrosis (ARN) is a rare but serious eye condition characterized by the rapid inflammation and necrosis of the retina. It is typically caused by a viral infection, most commonly by members of the herpesvirus family, including Herpes simplex virus (HSV) types 1 and 2, Varicella zoster virus (VZV), and less frequently by Epstein-Barr virus (EBV) and Cytomegalovirus (CMV).

Symptoms

The initial symptoms of ARN can be non-specific and may include eye pain, redness of the eye, sensitivity to light, and blurred vision. As the condition progresses, patients may experience a rapid decline in vision due to the involvement of the retina and the underlying choroid layer.

Causes

ARN is primarily caused by a reactivation of latent herpesvirus infection within the body. The exact mechanism by which the virus reactivates and targets the retina is not fully understood, but it is believed to involve the immune system's inability to keep the virus in check, leading to widespread inflammation and tissue damage.

Diagnosis

Diagnosis of ARN involves a comprehensive eye examination, including fundoscopy, which reveals characteristic patterns of retinal necrosis. Additional tests may include blood tests to identify the causative virus, polymerase chain reaction (PCR) testing of the vitreous or aqueous humor to detect viral DNA, and imaging studies such as fluorescein angiography to assess the extent of retinal involvement.

Treatment

Treatment of ARN is aimed at controlling the viral infection and reducing inflammation to prevent further damage to the retina. This typically involves the use of antiviral medications such as Acyclovir, Valacyclovir, or Famciclovir, often in combination with corticosteroids to reduce inflammation. In some cases, surgical intervention, such as vitrectomy, may be necessary to remove the vitreous gel and replace it with a saline solution to maintain the eye's shape and prevent retinal detachment.

Prognosis

The prognosis for patients with ARN can vary widely depending on the promptness of diagnosis and treatment. Early intervention with antiviral therapy and corticosteroids can help to preserve vision, but some patients may still experience significant vision loss or blindness in the affected eye. Regular follow-up with an ophthalmologist is essential for monitoring the condition and managing any complications.

Prevention

Prevention of ARN involves the management of systemic herpesvirus infections and maintaining a healthy immune system. For individuals with a history of herpesvirus infections, antiviral prophylaxis may be recommended to prevent reactivation.