PHOTOCHROMIC COMPOUNDS FOR USE IN THE TREATMENT OF EYE DISORDERS

The present patent application relates to compounds of formula (1) wherein Y and Z are independently O, N, P; R, R1, R2, R3, where present, are independently H, optionally substituted C1-C12 alkyl, O, or R and R1 and/or R2 and R3 form, together with the atom Y and/or Z to which they are attached, a 3-14 membered ring, optionally containing one or more additional heteroatoms selected from O, N, and S, optionally substituted, compositions comprising such compounds and the medical use of such compounds.