Cytomegalovirus Retinitis - Causes, Symptoms, Diagnosis, and Management

Introduction

AIDS is a life-threatening condition caused by the dreadful human immunodeficiency virus (HIV). HIV infection is usually spread by sexual contact or contact with the infected saliva, body fluids, sharing razors, etc. It is considered life-threatening because it affects an individual's immune system and gives way to opportunistic infections. Cytomegalovirus retinitis is one such opportunistic infection of HIV infection. Many other immune-weakening disorders can also cause it. However, the retinal layer of the eye is primarily affected. Cytomegalovirus is a type of herpes virus. In people with weak immune systems, like in an individual with HIV infection, the retinal layer of the eye gets infected by cytomegalovirus. As a result, the retina becomes necrosed, which results in detachment and tears. Cytomegalovirus retinitis infection is common among males and females aged 20 and 50.

Cytomegalovirus can be transmitted in various ways:

• From infected mother to child through the placenta. If the child escapes placental transmission, the child may acquire the virus from vaginal secretions during vaginal delivery.

• Through organ transplantations and blood transfusions.

• Through saliva while sharing food and drinks.

• In adult groups, sexual intercourse is the main mode of transmission.

• Transmission through the fecal-oral route is also possible, and cases are recorded.

What Are the Symptoms of Cytomegalovirus Retinitis?

CMV retinitis infection will initially show signs in one eye and then start in the other. The most common signs and symptoms of cytomegalovirus retinitis are as follows.

• Floaters can be seen in the field of vision. Floaters can appear as a speck or a dot and cause disturbances in viewing things.

• Photosensitivity or light sensitivity can be noticed.

• Pain in the eyes.

• Blind spots can be noticed in the center field of vision.

• Blurred vision will occur as the infection infects the retinal layer and damages the optic nerve, which is responsible for sending vision signals to the brain.

• Shadows along the peripheral vision can be seen.

• In extreme cases, it can result in blindness, too.

What Are the Causes of Cytomegalovirus Retinitis?

Cytomegalovirus retinitis is caused by cytomegalovirus, a type of herpes virus. Most humans will come in contact with cytomegalovirus at least once. However, only the ones with a weaker immune system will get infected severely and show signs and symptoms. Conditions that weaken the immune system and give way to CMV infections like CMV retinitis are,

• Human immunodeficiency virus (HIV) infection or acquired immunodeficiency syndrome (AIDS). HIV/AIDS is the most common cause of cytomegalovirus infection.

• Bone marrow transplant patients will have a weaker immune system till three to twelve months after the procedure.

• Cancer patients undergoing chemotherapy will generally have a weak immune system.

• Even organ transplant patients will have a weak immune system.

• Certain drugs like Prednisone, Dexamethasone, Dapsone, Methotrexate, Sulfasalazine, and Hydroxychloroquine can suppress the immune system.

• Aplastic anemia (a rare disorder that impacts the bone marrow's ability to produce blood cells).

Who Is at Risk of Acquiring Cytomegalovirus Retinitis?

Those people with a weaker immune system are at higher risk for acquiring cytomegalovirus retinitis. People with the following conditions are more likely to develop CMV retinitis.

• Human immunodeficiency virus (HIV) infection and acquired immunodeficiency virus syndrome (AIDS).

• People who are undergoing chemotherapy to treat cancer or leukemia.

• People who are undergoing organ transplants, specifically bone marrow transplants.

What Are the Possible Differential Diagnosis of Cytomegalovirus Retinitis?

Some of the conditions that can be misunderstood in place of CMV retinitis are,

• HIV retinopathy - It is characterized by internal bleeding and a cotton wool appearance. Thus, it is often a mistaken place for CMV retinitis. HIV retinopathy is more common than CMV retinitis.

• Syphilis (a bacterial infection).

• Toxoplasmosis (an infection caused by the parasite Toxoplasma gondii).

• Tuberculosis (TB, a bacterial lung infection).

• Behcet disease (a specific kind of inflammatory illness that impacts several body areas).

• Bacterial endophthalmitis (an infection affecting the internal organs of the eye).

What Are the Complications Associated With Cytomegalovirus Retinitis?

If CMV retinitis is left untreated, it may progress to cause,

• Retinal detachment.

• Necrosis of the retina.

• Damages to the optic nerve.

• Blindness - Permanent or temporary.

What Are the Three Stages of Retinitis?

A retinitis condition shows three patterns in general, and they are:

• Hemorrhagic: Behind the necrotic retinal layer, large spots of hemorrhage can be seen.

• Brush Fire: It is characterized by yellow-white lines in the margins of a necrotizing retina.

• Granular: There will be hemorrhage spots present. Instead, white granular lesions can be seen along with the infected retinal layer of the eye.

How to Diagnose Cytomegalovirus Retinitis?

Diagnosis of CMV retinitis will include physical examination, lab tests, and imaging tests. The physical examination will include proper pupil dilation to study the retina clearly and find hemorrhagic spots, retinal detachments, etc. Imaging studies will include ultrasonography to study the severity of retinal detachment and fundus photography to assess the retinitis condition in general. Lab tests will include a polymerase chain reaction to detect the presence of cytomegalovirus.

How to Manage Cytomegalovirus Retinitis?

Managing the HIV infection (if it is the cause) is mandatory as a further decrease in the CD4 plus cells may cause CMV retinitis again and again. Before the advent of antiretroviral therapy, managing CMV retinitis was a task. But now, with appropriate treatment, it can be managed more.

Antiretroviral drugs like Cidofovir, Foscarnet, and Valganciclovir can help manage the condition. These medicines can be taken as an oral pill, injection into the vein and eyes, or as an eye implant, giving out medicines at a particular pace. However, taking medications for a long time can make CMV resistant to drugs. Thus, the condition must be treated immediately without any delay.

How to Prevent CMV Retinitis?

The only way to prevent cytomegalovirus retinitis is by taking appropriate antiretroviral drugs in case of HIV infection. However, the condition may become severe if proper treatment is not undergone, leading to opportunistic infections like CMV retinitis.

What Is the Prognosis of Cytomegalovirus Retinitis?

Even with treatment, the disease may deteriorate to the point of blindness. This progression may occur because the patient's immune system has declined or because the virus develops resistance to the antiviral medications, rendering them ineffective. Retinal detachment, where the retina separates from the posterior part of the eye and results in blindness, is another possible consequence of CMV retinitis.

What Are the Complications of Cytomegalovirus Retinitis?

The following complications could arise:

• Impairment of kidney function (caused by medications utilized to manage the condition).

• Low white blood cell count (caused by the condition's medication).

When to Speak with a Medical Expert?

Contact a doctor if the symptoms worsen, fail to get better with medication, or experience additional symptoms. Individuals living with HIV who experience visual impairments should schedule an eye exam as soon as possible, especially if they have an extremely low CD4 count.

Conclusion

CMV retinitis has immense potential to cause blindness that can be reversed with any treatment or medications. Thus, prevention is the only cure. Typically, a CMV infection only manifests as symptoms in immunocompromised individuals. A compromised immune system can result from certain illnesses and medications, including HIV/AIDS and cancer treatment.