Corning Inc., Corning, NY, has signed a definitive agreement to purchase Optical Corporation of America, Marlborough, MA. Terms of the deal were not disclosed. Corning plans to integrate its new assets with its Photonic Technologies Div. In another business development, Corning has invested in an equity venture with Samara Cable Co. of Russia. The new entity, Samara Optical Cable Co. Ltd., will manufacture optical-fiber cables for telecommunications applications, primarily in Russia.