Is a man sinful if he is touched by an optometrist who is immodestly dressed during an examination, knowing that she is unlawful for him?

Firstly: It is not permissible for a woman to treat a man except out of necessity. Physicians should specialize in treating men, and female doctors for women, with the exception of extreme necessity. It is not permissible for a man to go to a female doctor for treatment if there is a male doctor available, and the prohibition is confirmed if the female doctor is adorned (uncovered).

Secondly: It was narrated from Ma'qal ibn Yasar, may Allah be pleased with him, that the Prophet, peace and blessings be upon him, said: "For one of you to be stabbed in his head with an iron needle is better for him than that he should touch a woman who is not lawful for him."

Thirdly: The hadith (definition) indicates a severe warning against touching a non-mahram (definition) woman, and that being stabbed in the head with an iron needle is easier than touching a woman who is not lawful for him.

Fourthly: The basic principle is that a man's touching a non-mahram woman is not permissible except in cases of extreme necessity, because that is a cause of temptation. It has been reported that the Prophet, peace and blessings be upon him, never touched the hand of a non-mahram woman at all.