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     Thirty years ago CMV retinitis was an extremely rare disease occurring only in immuno-compromised cancer patients. I remember in medical school here at Baylor being told by my professor while caring for a cancer patient with CMV retinitis that I probably would never see another case even if I decided to specialize in cancer treatment.  With the onset of the AIDS epidemic CMV Retinitis became very common and is the most frequent ocular complication of AIDS affecting 20-30% of the AIDS population.  CMV retinitis is caused by the Cytomegalovirus (CMV) and is a species specific (humans only) DNA virus of the herpes group. These are the same family of viruses that cause chickenpox, shingles and fever blisters.

     CMV Retinitis usually occurs only in one eye at a time and it is rare to develop it in the second eye when the patient is placed on anti-CMV therapy. If the patient is not on anti-CMV therapy approximately 60% of people will eventually develop CMV in their other eye. CMV virus is a very bad virus in that the tissue (retina) that it infects dies and becomes non-functional. CMV can progress slowly or rapidly across the retina with a frontline of white active infection (CMV moves by infection of adjacent retina) and the previously infected retina becomes pigmented and scars down.

Active CMV Retinitis The infected white leading edge of CMV moves up to the right to infect the normal retina.   Previously infected, now dead, retina is left behind causing a blind spot in the vision.

     Laboratory findings in AIDS patients are very important for following patients with this disease.  T-cells are white cells in the blood that help fight infection and are particularly important in fighting CMV.  If the T-cell count is above 100 it is very rare to develop CMV retinitis however, if the T-cell count drops below 40 (the T-cells can not fight off CMV) then CMV retinitis may develop. Ophthalmologists therefore follow patients very closely who have low T-cell counts (or high viral titers).

     Our therapies against CMV Retinitis are ever expanding. Ganciclovir, which is a virusstatic (stops the CMV from proliferating) medication, is effective against many members of the herpes group including CMV retinitis, Herpes Simplex I & II, the varicella virus (chickenpox), and the Epstein-Barr virus. Ganciclovir is many times used as an intravenous medication and can also be used as an oral medication.   Most recently ganciclovir has been placed in a plastic implant that is actually placed in the eye that is infected.  The side effects of ganciclovir to the body are minimized and the treatment to the CMV retinitis itself is maximized. This implant is a sustained released implant that can be effective for up to one year. Longer acting implants are under development.  RVT participated in the Ganciclovir Implant Studies. 

Ganciclovir Implant Implant with time-released ganciclovir placed through pars plana of the eye.   Ganciclovir is released for up to a year treating only the eye implanted without the side effects of systemic treatment.

Foscarnet is another treatment for CMV retinitis and is a virusstatic medication  studied in detail in the Study of the Ocular Complications of AIDS (SOCA). Consult SOCA to learn more about the SOCA studies from the National Eye Institute. More recently medications called anti-sense drugs have been developed in the treatment of CMV Retinitis by ISIS Pharmaceuticals. Anti-sense drugs are a new approach to treatment in that their design is to "kill the messenger".   ISIS 2922 (the drug) actually blocks mRNA, the messenger that tells the cell to produce the proteins necessary for the disease to progress and therefore, works not against the virus itself, but against the production of proteins necessary for the infection to progress.  This medication requires injection into the eye however, is effective in treating CMV retinitis. RVT was a study center for both the ganciclovir implant study and the ISIS trials in the United States.

     The major complication of CMV retinitis, in addition to the infection itself, is retinal detachment which occurs in approximately 20-30% of people who develop CMV retinitis. Some factors for the development of a retinal detachment include the size of the infected area, the location of the infected area (anteriorly located retinitis is more common to develop detachment), medical treatment (delays the onset of retinal detachment), myopia which is a risk factor for retinal detachment in any patient, and history of retinal detachment in the fellow eye. Surgical therapy for CMV retinitis detachment includes all of the treatments commonly used for retinal detachment repair but the highest success rate appears to be with the use of vitrectomy (see vitrectomy), laser and the use of silicone oil to push the retina into place. In a cumulative series of patients with CMV retinitis detachments the success rate was 83% in repairing the retina with vitrectomy and silicone oil.

CMV with Retinal Detachment Large area of retinal detachment including the macula (center of vision) in a patient with CMV retinitis from AIDS.  Only a small area of attached retina (arrow) remains.

     With the addition of multiple medications therapy in the treatment of AIDS, CMV retinitis has become much more rare in the past couple of years particularly with the use of protease inhibitors. Hopefully, we will soon have vaccines and even stronger preventative drugs that will make this disease rare again.

Disclaimer Stuff: The opinions expressed in this website are those of RVT.  Diagnosis and therapy should be based on a thorough examination by and recommendations of a qualified eye provider.