Joe Hudson has resigned as president of Transitions Optical, the joint venture between PPG Industries and Essilor International, after less than two years in the job. He is being replaced on an interim basis by Rick Elias, vice president of PPG for optical products and a former president of Transitions. Hudson replaced Elias as Transitions' president in September of 1998 after working up his way at PPG from marketing research analyst in 1985 to general manager of glass products for the Asia/Pacific region. A 10-year old firm, Transitions employs 1,000 persons around the world. It recently introduced its 4th generation variable tint coating technology, Quantum, which has been adopted sofar by Essilor, Sola, Vision-Ease and Seiko.