Cytomegalovirus retinitis

Eye

The eye is the organ of sight, a nearly spherical hollow globe filled with fluids (humors). The outer layer or tunic (sclera, or white, and cornea) is fibrous and protective. The middle tunic layer (choroid, ciliary body and the iris) is vascular. The innermost layer (the retina) is nervous or sensory. The fluids in the eye are divided by the lens into the vitreous humor (behind the lens) and the aqueous humor (in front of the lens). The lens itself is flexible and suspended by ligaments which allow it to change shape to focus light on the retina, which is composed of sensory neurons.

Also known as: CMV retinitis

Definition

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 people are exposed to CMV in their lifetime, but typically only those with weakened immune systems become ill from CMV infection. Serious CMV infections can occur in people who have weakened immune systems due to:

  • AIDS
  • Bone marrow transplant
  • Chemotherapy
  • Drugs that suppress the immune system
  • Organ transplant

Symptoms

Note: Many patients with CMV retinitis have no symptoms.

Symptoms include:

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 or less.

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 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, but this is rarely done.

Treatment

The goal of treatment is to stabilize or restore vision and prevent blindness. Long-term treatment is often needed. Medications may be given by mouth (orally), through a vein (intravenously), or injected directly into the eye (intraviteously).

Expectations (prognosis)

The disease will sometimes get worse, even with treatment, because antiviral medications stop the spread of the virus but do not destroy it.

Complications

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 vision problems should make an appointment for an immediate eye exam and should consider taking preventive treatment for CMV retinitis.

Prevention

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.

References

Drew WL. Cytomegalovirus. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 399.

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Review date:
December 1, 2009
Reviewed by:
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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