Well, first, you should know that the cornea is a protective domed layer of clear tissue covering the front of the eye. According to some experts, if you have corneal edema, the cornea becomes overly hydrated by accumulated fluid. In common, some symptoms such as blurred vision, visual disturbance will occur, when you have corneal edema. One of the major ways to treat corneal edema is to pinpoint the cause of the condition and treat it under the care of an eye doctor. In common, if it's caused by an eye infection, you can take some eye drops to treat the infection. Also, if the problems are related to contact lenses, you can just console it with your doctor, and he can give you some advices.
For the causes, it includes infection, glaucoma, post-operative eye changes, trauma, poorly-fitting contact lenses or overuse of contact lenses. Anyway, you should pay more attention to it.