I asked some of the other forum ophthalmologists to comment on your question but so far none has. If they do I will post their response.
For completeness I will state that the most common cause of the light changing during intercourse is the use of the medications Viagra and Cialis. This is so called blue vision.
Other drugs that might cause this include heavy use of alcohol, amyl nitrate 'poppers'.
I believe you would need to start with a comprehensive medcial eye examination with an ophthalmologist (Eye MD).
If that exam is normal and the problem persists you may need to see a neurologist and have a general physical by an internist or your GP.
JCH MD
Where did the optometry forum go?
The optometrist resigned and we are in the process of changing the forum to a physician (EyeMD) format like most of the other forums on this webisite.
I am male, 49years old, and taking none of the meds you refer. Just noticed it, and it's a little disconcerting...........
If you are a male and taking Viagra or Cialis they can cause this as part of "blue vision". If you are not taking these medications or are a female I'm not coming up with any other ideas. Perhaps some of the other Ophthalmologists will have an idea or perhaps other people reading the forum could let us know if they have had similar problems.
JCH MD
I had the same problem after some strenuous actifity (no, it wasn't sex, still I won't tell what it was) and it persisted for about a week. I told my ophthalmologist about it and said to him, he was free to use it as a joke at an ophthalmologist convention - not the fact, but the reason why it happened - he laughed and left it at that.