CMV retinitis, otherwise known as cytomegalovirus retinitis, is a serious viral infection that is a member of the herpesvirus family. CMV retinitis occurs in the retina of the eye. This viral infection is especially threatening to people who have compromised immune systems. Because CMV retinitis is asymptomatic in its early stages, ophthalmologists should check anyone with a weak immune system for this virus.
Some people that should be checked for CMV retinitis include newborns, elderly, people undergoing chemotherapy, and those who have received organ transplants. Prior to the introduction of antiretroviral therapy in AIDS patients, CMV retinitis affected about one-third of AIDS patients. The infection was responsible for over 90% of HIV-related blindness.
In this article, we will uncover what CMV retinitis is, the symptoms, causes, and possible treatments.
Symptoms of CMV Retinitis
Unlike other health conditions affecting the eyes, CMV retinitis does not result in pain or redness. Rather, some characteristic symptoms of the affected eye include:
- Blurred vision.
While some reports suggest that, while having symptoms is common of CMV retinitis, these symptoms are often mild. Therefore, people frequently ignore them. Patients may not even realize that there is something wrong with their vision.
CMV retinitis typically begins in one eye and often ends up affecting both eyes. If it is left untreated, this virus can lead to a detached retina and complete blindness in as little as two to six months. This is why it is important to proactively watch out for symptoms and test for this virus.
Clinical experience has revealed that giving retinal exams only to patients who are experiencing symptoms is not a reliable method of diagnosing CMV retinitis. Instead, a systematic screening of any vulnerable patient is essential.
Causes of CMV Retinitis
CMV retinitis is caused by a herpes virus known as cytomegalovirus. Most people who have this virus are unaware that they suffer from the infection because they have no symptoms. This means that the virus will never cause them to have health related problems. Cytomegalovirus is a common source of infection in people and it typically lays dormant in a healthy body because the immune system is able to fight it off.
However, in people who have a weakened immune system, this virus can restore itself in the body and spread to the retina. This may lead to eye problems that threaten vision altogether. One way that the virus commonly spreads to the retina is from shingles on the forehead and the nose.
CMV infection is able to occur in various parts of the body, including the gastrointestinal system and the retina. Most of these infections occur when a person’s T cell count, the white blood cells that fight off diseases, drops below 40.
Serious CMV infections may happen in people who have a compromised immune systems due to:
- Having a bone marrow transplant.
- Taking drugs that suppress the immune system.
- Having an organ transplant.
- Having HIV/AIDS.
This otherwise innocuous virus can wreak havoc on people who are not able to fight it off by themselves.
CMV Retinitis Treatment & Prevention
Successful treatment of this virus requires specific medications in addition to the strengthening of the immune system. The immune system can be recovered through continual antiretroviral therapy. However, one should continue the specific treatment of CMV retinitis until the retinitis resolves.
Treating the Infection
Ganciclovir is the drug that is most commonly used for the treatment of CMV retinitis. The ophthalmologist will administer this drug through either an intravenous infusion or an intraocular injection. Alternatively, valganciclovir is a well-absorbed oral drug that can achieve equivalent results as intravenous ganciclovir. Other drugs are more toxic or expensive without having any additional effectiveness.
Right now, the intraocular ganciclovir injection is considered to be the only option in areas that have very few resources. This is due to the fact that intravenous ganciclovir and oral valganciclovir are both very expensive.
Local injections of ganciclovir are preferable to receiving no treatment at all, even though they do not address the underlying cause of CMV retinitis. Beginning treatment with these local intraocular injections in addition to taking oral valganciclovir is the best way to rapidly gain control of the infection when the disease is the most sight-threatening because it is near the optic nerve or macula.
Unfortunately, intraocular ganciclovir treatment is not readily available in resource-poor settings, and this issue will likely continue. There are also very few clinicians with proper training in administering this type of injection. Some local regulations restrict this treatment to be performed only be ophthalmologists.
While intraocular injection is a frightening and invasive treatment, it has a low rate of serious complications. However, patients often have a low acceptance rate for this treatment due to their fear of discomfort. This is especially true if the disease is found early on and the patient has not experienced any symptoms. Nonetheless, as CMV retinitis develops, more therapies will be required for treatment.
Preventing the Infection from Reoccurring
Once the immune function has been reinstituted, it is unlikely for the infection to reoccur. This means that any specific treatment of CMV retinitis is typically only needed for a limited amount of time.
After receiving an induction treatment, a patient is then put on maintenance therapy. The goal of this is to prevent the CMV retinitis from reactivating. Maintenance may continue for the entire life of the patient or just until their immune function is restored.
The cytomegalovirus is especially treatable if it is caught early. For this reason, vulnerable patients should be screened on a regular basis so the virus can be stopped before it progresses into complete blindness.
There are treatment options available and although some are expensive and uncomfortable, it is best to start them early and continue on with maintenance so patients are able to keep their eyes in proper health.