In a patient presenting with headache and eye complaints, Examination of right eye reveals: Right eye superotemporal quadrantanopia. Left eye reveals: Left eye superotemporal quadrantanopia, Left eye centrocecal scotoma. Likely site of lesion is -

The patient has :- Right superotemporal quadrantanopia Left superotemporal quadrantanopia Left centrocecal scotoma → Left optic nerve involvement e.g. toxic opic neuropathy It has also been explained that early central chiasmatic lesion due to pituitary adenoma can cause upper temporal quadrantanopia. So, best answer here is 'a' i.e. left optic nerve with optic chiasma.