CMV retinitis
Key points
- Cytomegalovirus (CMV) is a member of a group of herpes-type viruses that can cause many diseases, including retinitis (an inflammation of the retina of the eye).
- Cytomegalovirus, also known as CMV, is very common.
- CMV retinitis is diagnosed through a standard ophthalmologic exam.
- The objective of treatment is to prevent progression of the disease, which can lead to blindness.
Definition
Cytomegalovirus (CMV) is a member of a group of herpes-type viruses that can cause many diseases, including retinitis (an inflammation of the retina of the eye).
Causes, incidence, and risk factors
Cytomegalovirus, also known as CMV, is very common. The majority of 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 with impaired immunity (immunocompromised hosts), such as those with AIDS.
People undergoing chemotherapy, which weakens the immune system, or those receiving immunosuppressive drugs for bone marrow or organ transplants, are also vulnerable.
One serious CMV infection is CMV retinitis, which can cause blindness. Retinitis usually begins in one eye, but often progresses to the other eye. Without treatment, progressive retinal destruction will lead to blindness in 4 to 6 months.
Even with continuous treatment, the disease can become worse, causing 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 25-40% of developing retinal detachment, in which the retina detaches from the nerves of the eye, causing blindness. Systemic CMV infection can also occur.
About 25% of people with AIDS develop CMV retinitis. Therefore, AIDS patients with a CD4 count of less than 100 cell/ mm3 should be examined periodically for retinitis, even if they have none of the symptoms listed below.
An HIV positive individual with visual disturbances should seek medical attention and arrange for an exam.
Symptoms
Note: Many patients with CMV retinitis have no symptoms.
- floaters (small spots in the vision)
- decreased visual acuity
- loss of peripheral vision
- blurred vision
- blind spots
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.
Diagnosis of CMV infection can be made through the following tests:
- Blood or urine culture: a blood or urine sample is cultured to see if it will grow the virus in the laboratory. Results take as long as three weeks.
Written and revised by
Gerald Hurowitz, M.D.
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