TreatmentUpdate 67, Volume 8, No 3; April 1996
Sean Hosein

The retina is a group of cells in the eye that can sense light. When light falls on the retina, it sends signals to the brain which are transformed into pictures that we see. When CMV attacks the retina, it becomes swollen and inflamed, and vision is affected. This condition is called CMV retinitis. As scars in the retina form, vision is reduced and if left untreated, blindness will occur.

Standard treatment

Standard treatment is intravenous ganciclovir (Cytovene, DHPG) or foscarnet (Foscavir). Maintenance therapy consists of reduced doses of these drugs. Some doctors prescribe oral ganciclovir. When treatment no longer works, doctors may switch patients to the other drug or use a combination of ganciclovir and foscarnet. Others may request the new anti-CMV drug Vistide (HPMPC, cidofovir). Details on therapies for CMV appear in TreatmentUpdate 53 and 60.

Who gets CMV retinitis?

In North America, the people with HIV infection who are at high risk for developing CMV retinitis are those with less than 50 CD4+ cells. Not all people with this level of CD4+ cells will develop CMV retinitis. Although several research teams are developing sophisticated tests to use in predicting who will develop CMV-retinitis, these tests remain research tools. Thus, regular eye exams remain the only reliable way to detect CMV retinitis before it causes widespread damage.

An old test

A team of eye doctors who have been monitoring subjects with AIDS think they have now found a simple way to predict which people are at high risk for developing CMV retinitis. According to their results, dramatic decreases in CD8+ cell counts appear to be linked to the onset of sight-threatening infections.

Study details

Over a period of 6 years, researchers in Cleveland, Ohio monitored 93 subjects for signs of CMV retinitis. These subjects also had their CD4+, CD8+ and other blood cell measurements done within 3 months of their eye exams. There were 7 females and 86 males. All eyes were examined by the same ophthalmologist.

CD4+ cell counts

Of the 93 subjects, 17 developed retinitis and 76 did not. At least half the subjects who had retinitis had a CD4+ cell count of 15 cells. Among those who did not develop CMV, the equivalent figure was 76 CD4+ cells. This difference between the 2 groups was statistically significant; that is, not likely due to chance alone.

CD8+ cells

Among the subjects who did not develop CMV retinitis, half of them had a CD8+ cell count of at least 634 cells. The equivalent figure for those who did develop retinitis was 280 CD8+ cells. This difference was statistically significant.

Summary

In this study, subjects who had less than 50 CD4+ cells and less than 500 CD8+ cells were at high risk for developing CMV retinitis. These results are not surprising. In TreatmentUpdate 47 and 52, we reported on other studies where low levels of CD8+ cells were linked to the development of life-threatening infections and/or death. The doctors conducting this study suggest that larger studies be conducted to confirm their results.

References:

1. Lowder CY, Butler CP, Dodds EM, et al. CD8+ T lymphocytes and CMV retinitis in Patients with the Acquired Immunodeficiency Syndrome.American Journal of Ophthalmology1995;120:283-290.

2. Fiala M, Kermani V and Gronbein J. Role of CD8+ cells in late opportunistic infections of patients with AIDS. Research in Immunology 1992;143: 903-907.

3. Schlumpberger JM, Wolde-Tsadic G, Yao JFF et al. CD8+ lymphocyte counts and the risk of death in HIV infection. Journal of Family Practice 1994;38(1):33-38.

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Copyright © 1996 - TreatmentUpdate. Reproduced with permission. Reproduction of this article (other than one copy for personal reference) must be cleared through the Editor, The Canadian AIDS Treatment Information Exchange, 555 Richmond St. West, Suite 505, Box 1104, Toronto, ON, M5V 3B1 • Phone: 416-203-7122 • Toll Free: 1-800-263-1638 • Fax: 416-203-8284  http://www.catie.ca