What is Cytomegalovirus Retinitis?
Cytomegalovirus (CMV) retinitis is inflammation of the retina caused by viral infection. CMV is a common virus that infects people of all ages, but it is usually harmless in healthy persons. In people with weakened immune systems and in babies infected before birth, however, CMV can cause disease. CMV is one of a group of viruses known as herpes viruses. This group of viruses includes the herpes simplex viruses, varicella-zoster virus (which causes chickenpox and shingles), and Epstein-Barr virus (which causes infectious mononucleosis, also known as mono). In layman’s terms, CMV could therefore be considered a form of “eye herpes.” Once CMV is in a person’s body, it stays there for life (as is the case with most forms of herpes). According to the Centers for Disease Control and Prevention, 50 to 80 percent of American adults are infected with CMV by the time they are 40 years old.
Most healthy children and adults infected with CMV have no symptoms, or they experience mild symptoms such as fever, sore throat, fatigue, and swollen glands. In some cases symptoms are so mild that those infected may not realize it. Immune-compromised people with CMV retinitis typically have vision problems and require treatment to restore eye function and prevent blindness. The disease is progressive and may worsen even with treatment.
Who Is Affected by Cytomegalovirus Retinitis?
CMV retinitis was once a major health threat to persons with HIV in the United States because of their immune-compromised state. But thanks to the accessibly of highly active antiretroviral therapy (HAART) in this country, the disease is often prevented or its progress halted. However, the prevalence of CMV retinitis remains high among HIV-infected people living in resource-limited areas in other parts of the world, such as Asia and Africa. In the United States, CMV retinitis remains a concern for HIV-infected persons, or who have had other infections as a result of immune suppression. Any immune-compromised child or adult, especially a newborn or elderly person, is at risk for CMV retinitis. Immune compromised persons include those with serious medical conditions, such as acquired immune deficiency syndrome (AIDS), and those who are undergoing cancer treatments (for example, bone marrow transplant and chemotherapy) or organ transplant. If you take immunosuppressant medicines, you can increase your susceptibility to CMV infection. A suppressed or weakened immune system is less able to fight off invading bacteria, viruses, and parasites. Immunosuppressant medicines are used to treat a variety of illnesses, including autoimmune disease and allergic asthma.
Symptoms of Cytomegalovirus Retinitis
Although CMV retinitis may cause no symptoms in some persons, most others experience one or more of the following eye symptoms:
- Floaters
- Blurred vision
- Loss of peripheral vision
- Blind spots
Symptoms often begin in one eye and then progress to the other eye. Without treatment or improvement in the immune system, CMV retinitis can permanently damage the retina (the light-sensitive tissue lining the back of the eye) and the optic nerve, resulting in blindness. Blindness from eye herpes may also occur as a result of retinal detachment. Severely immune compromised persons with CMV retinitis and associated CMV systemic disease may experience generalized symptoms in addition to vision problems.
Diagnosing Cytomegalovirus Retinitis
Your ophthalmologist can diagnose CMV retinitis through a standard eye examination that includes dilation of the pupils and ophthalmoscopy. In this painless examination, eye drops are applied to your eyes to enlarge your pupils. This allows the doctor a better view of the back of your eye, also known as the fundus, which includes the retina, optic disc, choroid, and blood vessels. Your doctor will use an ophthalmoscope and shine a bright light in your eye to illuminate the structures in the fundus. If signs of inflammation are apparent in the retina or blood vessels, a diagnosis of CMV retinitis can be made. In some instances, a diagnosis of eye herpes infection may be made on the basis of results from blood or urine tests or tissue biopsy.
Treatment of Cytomegalovirus Retinitis
It can be difficult to treat cytomegalovirus infection. Long-term treatment is often required to restore vision and prevent blindness. Another important goal of treatment is to bolster the immune system. You may be treated with a variety of antiviral medications that can be taken orally, given intravenously, or applied directly to the eye. Which type of treatment you receive will depend on the location and severity of the retinitis, your level of immune suppression, the other medications you are taking, and your ability to comply with treatment. Medication is usually started at high doses for the first few weeks and then decreased.
Complications of Cytomegalovirus Retinitis
Blindness, the worst outcome of CMV retinitis, can occur even with regular treatment. The reason for this may be that the virus has become resistant to the medication you are taking or that your immune system has deteriorated. Retinal detachment has been reported in patients with CMV retinitis. Other complications associated with the drugs used to treat this condition include kidney impairment and a low white blood cell count.
Preventing Cytomegalovirus Retinitis
For people with weakened immune systems, it may be impossible to prevent CMV infection. CMV retinitis can recur. Seeing your eye care practitioner regularly is important.