@Gal_they @autistics Appeal to the doctor's ego. If you indicate you know something better he might refuse to help you. So try to make it look like his idea.
Disclosing autism is a difficult thing. You have a good chance they might treat you like a little kid if they know but they will be ableist even if you don't disclose it.
If you don't want to say you can tell them you're very light sensitive and need the lights to be dimmed (migraine is a good excuse) or