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Sir,

We describe a case of varicella zoster virus acute retinal necrosis (ARN) in an immunocompetent woman that was successfully treated with oral valganciclovir. We believe this to be the first reported case of the use of oral valganciclovir for ARN.

Case report

A 30-year-old healthy Caucasian woman was referred to our Uveitis Clinic with a 2-week history of increasing blurred vision and floaters in her left eye. She had recently recovered from varicella that she caught from her two children 2 weeks prior to her visual symptoms. She had no relevant past medical history. At the referral hospital 5 days earlier she was noted to have a left panuveitis and was treated with guttae dexamethasone 0.1% two hourly and guttae cyclopentolate 1% three times a day.

On examination her best-corrected visual acuities were 6/5 in the right eye and 6/36, improving to 6/12 with pinhole in the left eye. She was a low myope. There was no relative afferent pupillary defect. There were 3+ cells and 2+ flare in the left anterior chamber, and 3+ vitreous haze. Her left optic disc was swollen and there were two focal white patches of retinitis/retinal necrosis in the supero and infero-temporal peripheral retina, each patch being 3–4 disc diameters in size. The right eye was healthy. A provisional diagnosis of the acute retinal necrosis syndrome was made.

A left anterior chamber paracentesis was performed and varicella zoster virus DNA was detected in the aqueous using the polymerase chain reaction. As she was unable to stay in hospital for intravenous aciclovir therapy due to social reasons, she was commenced on a 3-week induction course of oral valganciclovir 900 mg twice daily. One week later her visual acuity had improved to 6/6 in the affected eye. The anterior uveitis had resolved and there was less vitreous haze. The focal areas of retinitis/retinal necrosis had reduced in size.

Two weeks later her visual acuity was 6/5 in the left eye. There was no active vitreous inflammation. The focal lesions had completely resolved leaving atrophic retina with associated pigmentary changes. She continued oral valganciclovir at the maintenance dose of 900 mg once daily for 2 more weeks and then switched to oral aciclovir 400 mg three times a day, which was continued for 3 months. Her full blood count and renal function remained normal during treatment.

Comment

The ARN syndrome is a necrotising retinopathy with potentially devastating visual consequences. Prompt diagnosis and treatment are necessary to limit retinal damage and preserve vision.1 Intravenous aciclovir is usually given for 14 days, and in immunocompetent patients oral aciclovir for a further 3 months. Argon laser photocoagulation is often performed in two rows anterior to the edge of the necrosis.

Valganciclovir is a valyl ester prodrug of ganciclovir that is well absorbed after oral administration and rapidly metabolised to ganciclovir in intestinal tissues and the liver. In a randomised controlled clinical study, valganciclovir was shown to have an efficacy comparable to that of i.v. ganciclovir for induction and maintenance treatment of newly diagnosed AIDS-related CMV retinitis.2 It has the potential to cause adverse effects similar to those known to be associated with ganciclovir, including neutropaenia, anaemia, and diarrhoea.3 Also, it may be carcinogenic and/or mutagenic, and could cause fertility and pregnancy complications.

To our knowledge this is the first report of the use of oral valganciclovir to treat ARN. Although expensive it still offsets the cost of prolonged intravenous treatment that necessitates hospital admission and the associated costs. Long-term i.v. administration of medication also reduces quality of life and can result in considerable catheter-related morbidity.

Although not yet licensed for varicella zoster infection, oral valganciclovir provides an alternative treatment option in herpesviral retinitis. Nevertheless, testing for toxicity should be part of routine management, and advice on adequate contraceptive measures will need to be given to females of reproductive potential.