Cytomegalovirus (CMV) retinitis is a viral inflammation of the retina of the eye.
Causes, incidence, and risk factors:
CMV retinitis is caused by a member of a group of herpes-type viruses. CMV is very common. Most adults have antibodies to CMV in their blood (indicating they have been infected) by age 40. Usually, CMV produces no symptoms. However, serious CMV infections can occur in people who have weakened immune systems due to:
- Drugs that suppress the immune system for bone marrow or organ transplants
Note: Many patients with CMV retinitis have no symptoms.
Retinitis usually begins in one eye, but often progresses to the other eye. Without treatment, progressive damage to the retina can lead to blindness in 4-6 months.
Even with regular treatment, the disease can worsen to blindness. This may be because the virus becomes resistant to the drugs so that the drugs are no longer effective, or because the patient's immune system has deteriorated further.
Patients with CMV retinitis also have a chance of developing retinal detachment, in which the retina detaches from the nerves of the eye, causing blindness. Systemic CMV infection also can occur.
Signs and tests:
CMV retinitis is diagnosed through a standard ophthalmologic exam. Dilation of the pupils and indirect ophthalmoscopy will show signs of CMV retinitis.
CMV infection can be diagnosed with blood or urine tests that look for substances specific to the infection. A tissue biopsy can detect the viral infection and presence of CMV virus particles.
The objective of treatment is to prevent the disease from progressing, which can lead to blindness. Therapy is often long term. Medications given by mouth (orally), through a vein (intravenous), or injected directly into the eye (intraviteous) are available for treatment.
The disease will often progress, even with treatment, because antiviral medications stop the replication of the virus but do not destroy it. CMV itself suppresses the immune system and may worsen the symptoms of other causes of immunosuppression .
Calling your health care provider:
If symptoms worsen or do not improve with treatment, or if new symptoms develop, call your health care provider.
People with AIDS (especially those with a very low CD4 count) who have visual disturbances should seek medical attention and arrange for an exam.
CMV infection that causes symptoms normally occurs only in those with weakened immune systems. People with AIDS who have a CD4 count of less than 100 should be examined regularly for retinitis even if they don't have symptoms.