Bright Sight

Oliver Backhouse, Consultant Eye Surgeon

Cytomegalovirus (CMV) Retinitis

Cytomegalovirus (CMV) is a viral infection that can cause damage to the retina which can lead to a disturbance of vision. The virus is common and affects many people without them knowing it but can give rise to a flu-like illness. It can lie dormant in the body and be awoken in people who have a reduced immune system from a variety of causes. In the eye it gives rise to symptoms such as floaters, flashing lights, blurred vision, or loss of part of the visual field but quite often patients can have no eye symptoms. Because of this, those who are at high risk of getting CMV retinitis are advised to have their eyes screened every 3 months.

The diagnosis of CMV retinitis is made by the clinical findings seen by an Ophthalmologist and confirmed on doing DNA analysis on a tiny sample of fluid from the front of your eye. This allows for the correct antiviral treatment to be started.


Valgancyclovir is a very effective tablet for CMV and is taken by the mouth. It has largely replaced the use of medicine given by the vein or surgically implanted into the eye. Sometimes other medicine is needed if the virus is thought to be resistant to Valgancyclovir.


If caught and treated early, the prognosis can be good providing the macula (the part of the retina that sees fine detail) has not been affected. If the cause of the reduced immune system can not be reversed then lifetime treatment with Valgancyclovir is needed to prevent any recurrence. Unfortunately in some patients the recovery of the immune system causes its own problems with a condition called immune recovery uveitis. This can cause loss of vision due to inflammatory fluid collecting at the macula. This can be very difficult to manage and requires the close attention of a Uveitis specialist.