Should I go to the ER for what I think is a corneal ulcer? Or can I wait a day to go to my eye doctor?

You can wait. Most ulcers of the cornea occur under a contact lens, so remove that right away. Most eye doctors will see you quickly for a suspected corneal ulcer, so go next morning to their office as soon as they open and they will work you in for this type of condition. If you go to an ER you have a good chance of sitting there for several hours before you will even be seen and they will call for eye help.

Related Questions

I have a small white corneal ulcer, no pain or discharge just minor dry eye. My doctor cannot see me for 3 days, any tips to get me through till then?

Antibotics. Just make sure you have antibiotics drops or ointment. Otherwise if the symptoms are minor i would not worry too much. Read more...
Yes. If it is only related to dry eye, frequent use of unpreserved artificial tears should allow the "ulcer" to heal. If the "ulcer" is not improved in 12 hours, go in as an emergency if they will not see you, find another eye doctor. Read more...