CMV retinitis
Alternative names:
chorioretinitis
Definition:
Cytomegalovirus (CMV) is a member of a group of large herpes-type
viruses that can cause many diseases.
Causes, incidence, and risk factors:
CMV retinitis occurs in approximately 25% of AIDS patients
and can become a sight-threatening infection. Retinitis
usually begins in one eye, but progression to the other eye
is common. Systemic CMV
infection may also be present. Even with continuous treatment,
progression of the disease to blindness
can occur. This may result from viral resistance to drugs,
or from continued deterioration of the person's immune system.
Cytomegalovirus, also known as CMV, is very
common. Eighty-five percent 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.
Update Date: 04/01/00
Updated By: Luis A. Diaz, Jr. M.D., Johns Hopkins Medical Institute, VeriMed
Health Network
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