Hello Ms. Pitt, conjunctival hyperenia happens when the blood vessels of the eyes become dilated, so the conjunctiva looks red. Conjunctiva is the clear, thin membrane that covers part of the front surface of the eye and the inner surface of the eyelids. . The congestion of eyes can be superficial or deep. Conjunctival hyperenia is the one on the surface, which looks bright red, the deep on looks dark red, called ciliary congestion. Of course the superficial one is easier to treat. The conjunctival hyperenia can originate from infection or allergy or even contact of toxic chemicals. Usually people can feel pain in the eyes, blurred vision, increased eye discharge. When you have the symptoms, it's recommended to see an eye doctor. Treatment depends on the cause of the problem. In serious cases, it can cause vision loss.