Materials and methods of treating an eye with a hydrogel formed on the eye. Embodiments are provided that include post-keratectomy bandages. A method of treating a patient by application of a hydrogel bandage to a cornea by providing a first hydrogel precursor in a dry form immobilized in a first deposit at a first location in a well, providing a second hydrogel precursor in a dry form immobilized in a second deposit at a second location in the well, mixing the deposits together to form a mixture, and transferring at least some of the mixture to the cornea, with the mixture forming a covalently crosslinked hydrogel on the cornea.