Tue. Jul 14th, 2026

NEWNMCLE

WE ACCEPT KHALTI PAYMENT [NOTE:FOLLOW THE TEXTBOOK]

ACUTE RETINAL NECROSIS

Etiology

Acute retinal necrosis (ARN) is a rare clinical syndrome caused by any of the following viruses:

  1. Varicella-zoster virus (VZV). It is the commonest cause of ARN, particularly in older patients.
  2. Herpes simplex virus 1 and 2 (HSV 1 & 2) both cause ARN, typically in younger patients.
  3. Cytomegalo virus (CMV) can also cause ARN, very rarely.

Clinical features

Symptoms include decreased visual acuity, floaters, ocular discomfort, pain and photobhobia.

Signs are as follows:

  1. Anterior segment may or may not show signs of inflammation in the anterior chamber.
  2. Vitritis is usually marked
  3. Retinal lesions include areas of focal , well demarcated peripheral necrotising retinitis , associated with occlusive arteritis . Posterior pole is typically spared.

Complications include: retinal detachment (rhegmatogenous or tractional), and ischemic optic neuropathy.

Treatment consits of :

  1. Systemic antiviral drugs e.g. aciclovir i.v. 10 mg/kg body weight TID, for two weeks then PO dose for 6 -12 weeks. Alternative drug is valaciclovir. Note: Lifelong antiviral cover is required in immunosuppressed patients.
  2. Systemic steroids are needed to control inflammation.
  3. Aspirin to prevent arterial occlusion.
  4. Barrier laser photocoagulation for retinal breaks.
  5. Vitrectomy with silicon oil injection for associated retinal detachment.

PROGRESSIVE OUTER RETINAL NECROSIS

Progressive outer retinal necrosis is a very rare devastating necrotizing retinitis caused by a Varicella Zoster Virus (VZV) infection in immunocompromised patients (usually in patients suffering with AIDS with CD4+ T-cell counts < 50/mm2.

Clinical features

  1. Painless rapid loss of vision in one or both eyes is the presenting symptom.
  2. Retinal lesions include rapidly coalescing white areas of outer retinal necrosis (often central as well as peripheral ) but with minimal vasulitis, retinitis or viritis (cf ARN). Retinal detachment is an extremely common complication.

Treatment consists of intravenous injection of ganciclovir or foscarnet combined with intravitreal ganciclovir.

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