Is Looking At Non-Mahrams Prohibited Even Without Lust?
Prohibition comes with a reason or cause. The prohibition of looking at a woman for a man and man for a woman is to avoid lust which may leads to zina. this is preemptive measures. When there is no such thing is involved, one can look at a woman for example for a doctor it is allowed to examine a woman, vice versa. after accidental glance when one look back it is in most of the cases is not supposed to be a glance with some good intention. but while talking to some colleagues for example, causally looking at each other does not matter. still a glance with a bad intention is needed to be avoided.