SAN DIEGO (AP) - A San Diego County pharmaceutical company announced Thursday test results of a drug that delays the progression of blindness in AIDS patients and produces no side effects. Isis Pharmaceuticals Inc. based in Carlsbad, Calif., and CIBA Vision Corporation of Atlanta, presented the results on the fomivirsen (ISIS 2922) drug in Chicago at the Fifth Conference on Retroviruses and Opportunistic Infections, a meeting of the world's top AIDS investigators. The drug is under evaluation as a treatment for cytomegalovirus (CMV) retinitis, which eventually leads to blindness in AIDS patients. The disease is an infection that progressively destroys the retina. "Fomivirsen could be an important alternative for patients with this debilitating complication of HIV disease," said Daniel Kisner, a physician, and president and CEO of Isis Pharmaceuticals. To test the drug, the company treated patients with newly-diagnosed CMV retinitis, and those whose disease was in advanced stages, but had not responded to other treatments. The drug was administered by injection once a week for three weeks, and once every other week for maintenance. The trials found progressive blindness in patients who had not responded to other drugs was delayed, sometimes up to almost two years. Those who were newly-diagnosed with the complication did not suffer symptoms for more than a year, and the progression was slow after that time. About 20,000 of the 250,000 patients with full-blown AIDS in the United States suffer CMV retinitis and potential blindness, according to Isis spokeswoman Jane Green. The reason fomivirsen is more effective than other drugs is because it works at the genetic level to interrupt the process by which proteins involved in human disease are produced, she said. Traditional drugs are designed to interact with protein molecules that support or cause diseases throughout the body. Antisense drugs are designed to inhibit the production of disease-related proteins. Fomivirsen inhibits the virus that causes CMV retinitis in AIDS patients. The next step for the company is asking the federal Food and Drug Administration to approve the drug as a marketable, medical treatment. Last year, Iris and CIBA Vision, the eye care unit of the Switzerland-based Novartis AG, established a worldwide distribution agreement for fomivirsen should it get approved by the FDA and European drug regulators. Isis Pharmaceuticals, founded in northern San Diego County in 1989, is a drug research and development company that currently has six compounds in human clinic trials, including treatments for Crohn's disease and cancer. CIBA Vision is a researcher, developer and manufacturer of optical and ophthalmic products and services including contact lenses, lens care products and ophthalmic pharmaceuticals. The core businesses for Novartis AG, which has 87,000 employees in more than 100 countries, are healthcare, agribusiness and nutrition.