While it could be allergies it would be best to have her eyes examined and rule out any other issues. There are a myriad of things that can be causing this irritation and it would be best to find out the cause then merely treat the symptoms. Good luck.
You really don't want to mess around with vision, and chronic red eyes need to be checked by a veterinarian to determine the cause. For temporary relief, you can flush the eyes with sterile saline solution, or use "artificial tears" drops. DO NOT use any over-the-counter products that "get the red out" like Visine.
Conjunctivitis can be caused by allergies, lack of enough tear production, or bacteria. There may be other reasons. Your vet should look at them.