The invention concerns photochromic compounds with general formula (I): ##STR1## where R.sup.a, R.sup.b and R.sup.c represent hydrogen; alkyl, aryl, OR, SR, COR or COOR, where R represents hydrogen, alkyl or aryl, amino with formula NR.sub.1 R.sub.2, where R.sub.1 and R.sub.2 each represent hydrogen, alkyl, cycloalkyl, or aryl, R.sub.1 and R.sub.2 may together form a heterocycle containing four to seven members with the nitrogen atom and may intracyclically contain one or more heteroatoms selected from nitrogen, oxygen, sulphur, or a halogen atom; a mono- or polyhaloalkyl; an NO.sub.2, CN or SCN group; n and m represent whole numbers from 1 to 4 depending on the number of substitutions on the nucleus and p is 1 or 2 depending on the number of substitutions on the nucleus; H is either an aromatic heterocycle condensed at the 5,6 or 6,7 positions, containing five or six members comprising one or more heteroatoms selected from nitrogen, selenium, oxygen and sulphur or an aromatic carbocycle containing five or six members, condensed at the 7,8 positions; all optionally substituted. The invention also relates to the use of these compounds in ophthalmic optics.