A sale of Paragon, which Valeant’s Bausch & Lomb unit purchased earlier this year for an undisclosed sum, would deal a blow to the specialty pharmaceutical company’s attempt to consolidate the market for gas permeable contact lenses, a type of rigid lens popular among people with keratoconus, a thinning disorder of the cornea, among other eye diseases. The FTC has been investigating Valeant for potentially cornering a portion of the lens market.