The Result Of Riboflavin/UVA Corneal Collagen Cross-linking With Isotonic Riboflavin Solution And Hypotonic Riboflavin Solution In The Treatment Of Keratoconus

BackgroundAs a new treatment method for keratoconus, riboflavin/UVA (370nm) corneal collagen cross-linkling (CXL) had been used in clinic for years. In standard CXL protocol, corneal thickness should be over 400μm, to protect endothelial cell count (ECD) and contact lens from UVA irradiation. With the development of the disease, corneal thickness less than 400μm in advanced stage, which limit the use of CXL in thin cornea. Ophthalmologists used hypotonic riboflavin solution instead of isotonic riboflavin solution to swelling thin cornea, thus CXL can be used in thin cornea to treat keratoconus. Studies about the long-term safety and efficacy of CXL in the treatment of keratoconus are still less, so we followed keratoconus patients for two years after CXL, aimed at exploring the long-term safety and efficacy of CXL in the treatment of keratoconus.ObjectiveTo evaluate the outcomes of riboflavin/UVA corneal collagen cross-linking (CXL) with isotonic riboflavin solution and hypotonic riboflavin solution.Methods74 eyes of 39 keratoconus patients were collected in our study. According to the corneal thickness before treatment, all eyes were divided into two groups:group A (thick cornea, corneal thickness over 400μm) included 18 patients (34 eyes) which undergone CXL with 0.1% isotonic riboflavin solution; group B (thin cornea, corneal thickness less than 400μm) included 21 patients (40 eyes) which undergone CXL with 0.1% hypotonic riboflavin solution. Central cornea epithelium was removed under aseptic condition. Illuminating riboflavin at an interval of 3 minutes for 10 times, irradiation UVA after corneal thickness over 400μm by OCT and yellow flare in the anterior chamber was monitored by slit-lamp examination. Irradiation parameters were as follow:wavelength of UVA was 370nm, irradiation energy density was 3mW/cm2, irradiation distance was 5cm, total irradiation time was 30 minutes. During irradiaton, riboflavin used before was illuminated at an interval of 3 minutes. After irradiation, a soft contact lens was given and antibiotics, non-steroidal anti-inflammatory eye drops were given four times a day for one week. The contact lens was revomed when epithelium was healed and adds steroids eye drops four times a day for four weeks. Record the corneal thickness (T), uncorrected visual acuity (UCVA), corrected visual acuity (CDVA), maximum keratometry (Kmax) and ECD for each follow, the total follow time was 2 years.ResultsT and Kmax decreased 2 years after CXL in both groups, UCVA and CDVA had an improvement in both groups and ECD had no significant changes 24 months after CXL in both groups.ConclusionsCXL can halt the progression of keratoconus. Isotonic riboflavin solution can be used for CXL in thick cornea keratoconus patients and hypotonic riboflavin solution can be used for CXL in thin cornea keratoconus patiens.