Photochromic spirodihydrophenanthropyrans

摘要

Specific photochromic spirodihydrophenanthropyrans and their use in synthetic resin materials of all kinds, particularly for ophthalmic purposes. The compounds of the invention are photochromic pyran compounds derived from 9,10-dihydrophenanthrene in which at least one of the two carbon atoms at positions 9 and 10 belongs to a further ring system and thus forms a spiro linkage point.