The U.S. Food and Drug Administration took steps to make more readily available an experimental drug that may prevent blindness in some AIDS patients. The drug, ganciclovir, is manufactured by Syntex Corp of Palo Alto. FDA officials said that patients with mild cases of cytomegalovirus retinitis will now have easier access to the drug. Previously, only patients with sight-threatening cases of the disease had been eligible to receive immediate access to ganciclovir. The FDA also said that on May 2, an advisory committee will review “new evidence” about the drug that may answer unresolved questions about its effectiveness. AIDS activists have criticized the FDA and other government officials for delays in reviewing the ganciclovir. They say it should be approved for prescription sales.