As we all know, the normal human cornea is histologically divided into five layers, of which 90% of the thickness of the stroma layer consists of nearly 200 layers of collagen fibers arranged in bundles of thin plates, these collagen fibers have the characteristics of high toughness and strong tensile strength, which is the determining factor for maintaining corneal tension. Conical cornea: A corneal condition characterized by corneal dilatation, resulting in the central portion of the cornea protruding forward, thinning to a conical shape, and producing high levels of irregular astigmatism and myopia, with a severe loss of visual acuity. The pathogenesis of the disease is related to the reduction in the amount of collagen or the abnormal distribution of collagen fibers due to structural changes. The only option for advanced lesions is corneal transplantation. Corneal Cross Linking (CCL): It is to activate riboflavin (a photosensitizer) with ultraviolet A light at 370nm to form reactive oxygen species, which induces chemical cross-linking between the amino groups of the collagen fibers, resulting in the thickening of the diameter of the collagen fibers, promotion of apoptosis of the corneal stromal cells, and improvement of the cornea’s resistance to a variety of degradation enzymes, thus making the cornea more resistant to a variety of biological effects. This will increase the mechanical strength of the corneal stroma and help to control the condition of patients in the early stages of keratoconus and prevent it from further deterioration. Indications for Corneal Cross Linking treatment: 1. Initial stage of cone corneal lesions; 2. Secondary cone cornea. Corneal Cross Linking treatment safety range: 1, corneal thickness greater than 450µm 2, corneal curvature less than 60D Corneal Cross Linking treatment process: 1, clean the eye before treatment, local disinfection; 2, local point surface anesthetics treatment for 30 minutes; 3, and then the role of riboflavin in the cornea for 25 minutes, then with a wavelength of 370 nanometers. Then a special light with a wavelength of 370 nanometers is used to irradiate the cornea for 30 minutes. Safety of Corneal Cross Linking Treatment: The wavelength of 370 nm light of CCL treatment passes through the corneal stroma and is rapidly attenuated and partially absorbed by riboflavin, only 7% of the light passes through the cornea, and when the cornea is thicker than 400 nm, it cannot damage the endothelium of the cornea and the tissues of the eye in the deeper corneal layer.