Hi Elizabeth,
I’m confused by the diagnosis of vascular keratitis but the specialist still needing a biopsy. I’m unsure what medications she is on but those may need to be altered. Further tests certainly could be needed to look for a cause however those are best left to specialist ophthalmologists. You can find one at the website of American College of Veterinary Ophthalmologists.
Best of luck.
Dr. Ryan Llera