A method for stabilizing collagenous eye tissues by nitrite and nitroalcohol treatment. The topical stiffening agent contains sodium nitrite or a nitroalcohol in a buffered balanced salt solution and can be applied to the surface of the eye on a daily basis for a prolonged period. Application of the solution results in progressive stabilization of the corneal and scleral tissues through non-enzymatic cross-linking of collagen fibers. The compounds can penetrate into the corneal stroma without the need to remove the corneal epithelium. In addition, ultraviolet light is not needed to activate the cross-linking process. The resulting stabilization of corneal and scleral tissues can prevent future alterations in corneal curvature and has utility in diseases such as keratoconus, keratectasia, progressive myopia, and glaucoma.