What is the max time for eye dilation before you should worry and to to the emergency room?

After drops?: Do you mean dilation that doesn't resolve after an exam? Then depends on the drop used, and i would call the office to find out which and ask that question (skip the ed). If you have had no drops, but one eye is dilated and the other is not, then you should go to the emergency room as this could be a serious issue (urgent neurologic problem such as aneurysm or carotid dissection are possible).

Depends: Any eye dilation without medication requires immediate visit to the er. Dilation with medications never need a visit to the er. There are some dilation medication that lasts 1-2 hrs, 4-5 hrs, 6-24 hrs, or several days. Pts vary as well. Some may have abnormal reaction causing dilation for several days from medication that should only last several hours. Call your ophthalmologist.