Can the eye doctor tell if you have a virus or a bacterial infection in your eyes?

Ophthalmologist!: As an infectious diseases specialist, i refer patients to an ophthalmologist (not an optometrist!) since they have the medical knowledge to determine viral and bacterial infections of the eye, since it may require their expertise to sample the fluid within the eye (vitreous sampling) and to possible instill an anti-infective into the eye.

Usually, but...: Examination at the microscope will often tell an ophthalmologist if a patient has a bacterial or viral infection. However, sometimes, certain infections, particularly viral ones, take several weeks to show their classic appearances. It's not unusual for a patient to present with a non-specific redness or irritation that develops into something completely different after a few weeks.