Complex sentence: The first of these was the Photolite lens sold in the early 1980s by American Optical Corporation, but the first commercially successful plastic photochromic lens was introduced by Transitions Optical in 1991.
Split into simpler sentences: The first of these was the Photolite lens sold in the early 1980s by American Optical Corporation. But the first commercially successful plastic photochromic lens was introduced by Transitions Optical in 1991.