Acute retinal necrosis syndrome (ARN) is a condition with an exact etiology that remains not fully understood. It is believed to be associated with herpesvirus infections and is characterized by retinal necrosis, vasculitis primarily involving the retinal arteries, vitreous opacities, and late-stage retinal detachment. It can occur at any age, with cases most commonly seen between 15 and 75 years. No significant gender differences have been noted, and the condition usually affects a single eye.
Clinical Manifestations
The onset is typically insidious, with symptoms such as eye redness, eye pain, or periorbital discomfort. Early signs include blurred vision and floaters, with significant vision loss occurring when the macular region becomes involved. Mild to moderate anterior segment inflammation may be observed, which can include mutton-fat keratic precipitates (KPs) and increased intraocular pressure.
Retinal necrosis is characterized by yellowish-white lesions with sharply delineated edges, often beginning in the peripheral retina. These lesions appear in a patchy (“thumbprint-like”) pattern, gradually coalescing and extending toward the posterior pole. Retinal vasculitis is a key feature, with involvement of both arteries and veins, although arterial inflammation is more prominent and may be accompanied by retinal hemorrhages. Mild to moderate vitreous opacity is observed in the early stages, progressing to marked opacification and subsequent fibrosis. During the recovery phase, multiple retinal tears commonly form in the areas of necrosis, leading to retinal detachment.
Diagnosis
Typical clinical manifestations facilitate diagnosis in most cases. During vitrectomy, small specimens may be collected for serum and vitreous antibody testing, as well as polymerase chain reaction (PCR) analysis, to identify the viral type. These tests, however, are not essential for diagnosis. Diagnosis is based on clinical features, but laboratory investigations such as vitreous and serum antibody testing, intraocular fluid analysis, or retinal and vitreous tissue biopsy are necessary for atypical cases. PCR can assist in detecting the DNA of varicella-zoster virus and herpes simplex virus in intraocular fluid.
Treatment
Antiviral Agents
Acyclovir is administered intravenously at 10–15 mg/kg three times daily for 10–21 days, followed by oral administration at 400–800 mg five times per day for 4–6 weeks. Alternatively, ganciclovir may be given intravenously at 5 mg/kg twice daily for 3 weeks, followed by a maintenance dose of 5 mg/kg per day for 4 weeks.
Corticosteroids
Concurrent with antiviral therapy, oral prednisone (30–50 mg/day) may be prescribed, with dosage gradually tapered after one week.
Laser Photocoagulation and Surgical Intervention
Laser photocoagulation may help reduce the risk of retinal detachment. For cases with retinal detachment, vitrectomy combined with intraocular gas or silicone oil tamponade can be employed.