Diphenhydramine is an antihistamine used to relieve symptoms of allergy, hay fever, and the common cold. These symptoms include rash, itching, watery eyes, itchy eyes/nose/throat, cough, runny nose, and sneezing. It is also used to prevent and treat nausea, vomiting and dizziness caused by motion sickness. Diphenhydramine can also be used to help you relax and fall asleep. This medication works by blocking a certain natural substance that your body makes during an allergic reaction. Its drying effects on such symptoms as watery eyes and runny nose are caused by blocking another natural substance made by your body (acetylcholine).
Diabetic retinopathy is the most well-known diabetes eye complication and can lead to blindness and vision problems. Diabetic retinopathy progresses through three clear stages: background neuropathy, maculopathy and proliferative retinopathy.
High blood sugar weakens the blood vessels in your eyes. That can make them leak or grow out of control in your retina, the light-sensitive area at the back of your eye. This is called diabetic retinopathy. When fluid seeps into your retina, it can cause diabetic macular edema.