The author used ion introduction method to successfully bring riboflavin through the corneal epithelium into the corneal parenchyma layer, followed by ultraviolet radiation to complete the treatment of corneal collagen cross-linking in a case of progressive conical cornea with 400 micron corneal thickness. The report is as follows. 1, clinical data Patient, female, 18 years old. She complained of progressive vision loss in both eyes for two years, with worsening double vision for one month. On examination, visual acuity right 0.1, corrected -5.00-6.00×1650=0.6. left 0.1, corrected -4.50-6.00×1450=0.6. corneal transparency in both eyes, localized bulging in the central area of the cornea below the temporal area, and positive Fleischeos ring were seen. Vogt’s striae were seen in the right corneal stroma. The corneal thickness was 400 microns on the right and 480 microns on the left. Corneal topography suggested cone corneal changes in both eyes. Clinical diagnosis: progressive cone corneal (1) Treatment Under oxybutynin hydrochloride surface anesthesia, 1% sodium riboflavin phosphate solution was spotted on the eyes. The positive electrode plate of the ocular ionizer was placed on the eyelid surface of both eyes, and the electrode plate of the right eye was energized with an ion introduction current intensity of 0.6 mA. The left eye was not energized as a control. Every 3 minutes, riboflavin sodium phosphate solution was dabbed on the eyes, and 30 minutes after treatment, the slit lamp microscopy showed that the right eye had yellow staining after the whole corneal layer, while the left eye had no obvious yellow staining. The cornea was irradiated for 30 minutes using a UV therapy device with a wavelength of 370 nM and an illumination level of 3.5 mW/cm2, during which riboflavin was spotted every 3-5 minutes. The left eye was treated with a riboflavin UV crosslinking method that removed the corneal epithelium. At the end of treatment, tobramycin dexamethasone drops were ordered four times daily for two weeks. 2, Discussion Classical riboflavin UV corneal collagen crosslinking requires removal of the corneal epithelium to allow riboflavin, which is a photosensitizer, to penetrate into the corneal parenchyma and generate oxygen radicals excited by specific wavelengths of UV irradiation, which act on chemical groups between and within corneal collagen fibers to form more covalent bonding linkages, thereby increasing corneal biomechanics. In the current UV corneal collagen cross-linking method of riboflavin for the treatment of progressive cone keratopathy, riboflavin is used as a cross-linking agent, and the amount of access to the corneal stroma will directly affect the effectiveness and safety of the treatment. Removal of the corneal epithelium results in several days of photophobia, tearing, ocular pain and discomfort, and increases the chance of corneal infection, [1. 2]. If the corneal epithelium is left relatively intact, the patient’s discomfort after treatment is reduced, and a certain corneal thickness is maintained, reducing the possibility of photodamage and reducing the chance of corneal infection. Some authors have used the method of preserving the corneal epithelium, which is also claimed to allow riboflavin to infiltrate the corneal parenchymal layer and achieve cross-linking. However, authors who question this epithelium-preserving method of administration point out that the concentration of the drug entering the cornea is not sufficient for cross-linking, and animal studies suggest that the epithelium-preserving method of administration produces much less cross-linking than the epithelium-removing method. Therefore, it is believed that cross-linking treatment with preserved corneal epithelium should not be a routine method, only for cases with thin corneal thickness. [3. 4] However, whether it is a minor mechanical disruption or a loss of the tightly connected barrier function of the corneal epithelium due to drug toxicity, topical application of riboflavin does penetrate the epithelial layer into the corneal parenchyma, which is only quantitatively rather than qualitatively different from the epithelial removal method of administration. Drug entry into the cornea is influenced by many factors, such as drug concentration, dosage form, osmotic pressure, pH, hydrophilicity/hydrophobicity, degree of attachment to the ocular surface, tear dilution, and drainage of the drug. Iontophoresis is a classical non-invasive method of drug release that allows ionized drug molecules to enter the tissue under the action of electric current movement. Although there has long been clinical practice of applying ion introduction method to ocular surface diseases, and some experiments have also confirmed that the method is safe and effective, and the concentration of drugs entering the eye through the ion introduction method in the anterior segment of the eye is much higher than that of topical drug dosing, [5-7], the method is still not widely recognized and accepted as the mainstream treatment in ophthalmology clinical practice, but mainly used for surface treatment of the skin. The author’s preliminary attempt to use ion introduction method to get riboflavin into the parenchymal layer of the cornea with the corneal epithelium intact, while no riboflavin infiltration was seen in the control eyes, suggesting that the drug ion introduction method can be used for UV cross-linking treatment of riboflavin with preserved corneal epithelium. Although corneal yellowing was visible under slit-lamp microscopy, more objective evidence to support this result is lacking, which relies on the next step of animal experiments for validation. Since the riboflavin solution in the conjunctival sac is rapidly diluted and drained by the tear fluid, frequent dosing and loading and unloading of electrode plates are required to ensure the local drug concentration, which is quite a cumbersome process. It is envisaged that this can be solved by changing the drug dosage form or controlled release method.