Washington  DC  May 26  2005---The US Food and Drug Administration is studying cases of blindness reported in men using the oral impotency drugs Viagra  Cialis  and Levitra The story was first reported by CBS news and confirmed by FDA spokesperson Susan Cruzan  who said that 43 reports of NAION (non-arteritic anterior ischemic optic neuropathy) had been reported---38 in men using Viagra  4 using Cialis  and one using Levitra