CMV Retinitis: Protecting Your Vision

The most well-known risk group is people living with HIV, especially those with advanced AIDS. Before the widespread use of modern antiretroviral therapy, a significant percentage of people with AIDS developed CMV retinitis. The infection typically occurs when CD4+ T-cell counts, a measure of immune strength, fall below 50 cells per microliter. It rarely develops when counts remain above 100 cells per microliter.

People with HIV who are not receiving treatment, or whose treatment has stopped working, face the highest risk. Very high HIV viral loads and a history of other opportunistic infections are additional risk factors.

People who have received solid organ transplants take immunosuppressive medications to prevent the body from rejecting the new organ. These medications weaken immune defenses and can allow CMV to reactivate. The risk is greatest when a patient who has never been exposed to CMV receives an organ from a donor who carries the virus.

CMV retinitis can also develop in other people whose immune systems are severely suppressed. These groups include:

• Patients undergoing chemotherapy for cancer
• People taking strong immunosuppressive medications for autoimmune conditions
• Newborns with congenital immune deficiencies
• Elderly individuals with significantly declining immune function

There is also evidence that potent local immunosuppression within the eye itself, even without widespread immune suppression throughout the body, may be a risk factor in some cases.

The primary treatment involves antiviral medications that fight CMV throughout the body. Approved options include ganciclovir, valganciclovir, foscarnet, and cidofovir. Oral valganciclovir is the most commonly used option today because of its convenience and reliable absorption. Treating the whole body is important because CMV can affect organs beyond the eyes.

Therapy typically begins with a higher induction dose for two to three weeks, or until the retinitis stabilizes. After that, the dose is reduced to a lower maintenance level to prevent the infection from returning.

In some situations, a retina specialist may deliver antiviral medication directly into the eye through an intravitreal injection, a carefully performed injection into the gel-filled space inside the eye. Ganciclovir and foscarnet can both be given this way. Intravitreal injections are often used alongside systemic therapy during the initial treatment phase to achieve faster control of the infection, particularly when it threatens the macula or optic nerve.

For patients with HIV, the most important long-term strategy is restoring the immune system through highly active antiretroviral therapy (HAART). The widespread use of HAART has dramatically reduced the number of new CMV retinitis cases and has significantly reduced the risk of disease progression. When CD4+ T-cell counts recover to a sustained safe level, the risk of CMV reactivation drops substantially, and maintenance antiviral therapy may eventually be discontinued under close medical supervision.

Research into new treatment strategies is ongoing. One promising approach is adoptive cell transfer, which involves giving patients an infusion of CMV-specific cytotoxic T lymphocytes, a type of immune cell trained to recognize and fight CMV. Early results from small studies have been encouraging. This approach may be particularly valuable for transplant patients who must remain on immunosuppression long-term and cannot easily restore their immune function through other means.

Yes, reactivation is possible, particularly if immune function declines again. The cytomegalovirus remains dormant in the body even after the retinitis resolves. Patients who stop maintenance antiviral therapy without adequate immune recovery, or those whose immune status changes due to illness or medication changes, are at meaningful risk for recurrence. This is why follow-up eye examinations continue even after the infection appears to be controlled.

The retinal infection itself does not spread from person to person. However, cytomegalovirus is a very common virus that can be transmitted between people through bodily fluids such as saliva, blood, and breast milk. The key distinction is that most people who carry CMV never develop retinitis, because a healthy immune system keeps the virus inactive. The retinitis complication only arises when the immune system is severely weakened.

Retinal tissue destroyed by the infection does not regenerate. Vision lost before treatment begins is typically permanent. Treatment can halt the spread of the infection and preserve the vision that remains, but it cannot reverse damage that has already occurred. This is why patients at high risk should have regular screening eye examinations even when they feel no symptoms, so that any infection is caught at the earliest possible stage.

The induction phase, with higher antiviral doses, generally lasts two to three weeks. After that, patients transition to a lower maintenance dose that may continue for months or longer depending on immune status. For people with HIV who achieve strong and sustained immune recovery through antiretroviral therapy, maintenance medication may eventually be stopped under careful medical supervision. Transplant recipients and others requiring long-term immunosuppression may need extended or indefinite monitoring.

The most effective prevention for people with HIV is consistent use of antiretroviral therapy to keep CD4+ T-cell counts well above 50 cells per microliter. For transplant recipients, antiviral prophylaxis medication may be prescribed during the period of highest risk after surgery. For all high-risk patients, regular dilated eye examinations provide the best opportunity to detect any early infection before vision loss occurs. Early intervention gives treatment the best possible chance of success.