If the pupils react to light she isn't totally blind.
When you move your finger quickly toward her eye she should flinch.
She should follow a moving object with her eyes.

A vet can use an ophthalmoscope to look inside the eye for cataracts,
check the retina, etc.  They can test for glaucoma with a device that
measures pressure.  Basically they can do anything an MD can do with a
human infant.