Hi. My Mom's Eye Has Swelled Up Gradually Over The

Hi. My mom's eye has swelled up gradually over the day. She has pain and irritation in the eye. No discoloration, or blurred vision or sensitivity to light. Warm compresses help only for a short period of time. No history of allergies. She does have high blood pressure and high blood sugar (both controlled by medication). Any ideas? Should she go to the ER? I'm worried about brain hemorrages and/or clots as I have heard that the first sign are eye symptoms (she has no history of heart disease and/or stroke). Thank you.