Corneal Ectasia After Small Incision Lenticule Extraction (SMILE) Treated By UVA/Riboflavin Crosslinking

Objective:Small incision lenticule extraction (SMILE) is "full femtosecond" laser surgical representatives, which can better retain the biomechanical properties of the cornea, reducing the risk of corneal ectasia. In theory, it’s more secure, stable and more efficient. Previous studies have shown that UVA/Riboflavin crosslinking improve the cornea biomechanical properties through enhancing the crosslink among the corneal collagen fibers. This treatment impede the progression of keratoconus and corneal ectasia, and have achieved the desired clinical outcome in patients with advanced keratoconus. This study analyzed the first clinical case of corneal ectasia after SMILE, summarized the therapeutic experience of UVA/Riboflavin crosslinking for treating corneal ectasia after SMILE, aiming to reveal the potential complications of SMILE, evaluating the efficacy of UVA/Riboflavin crosslinking for treating corneal ectasia after SMILE, and exploring the necessity and comprehensiveness of preoperative evaluation.Setting: Department of Ophthalmology, Shandong Provincial Hospital affiliated to Shandong University.Methods:1. We retrospective reviewed the preoperative, intraoperative, postoperative clinical data of the first corneal ectasia after SMILE. The whole clinical data, including treatment data, corneal topography, refraction and so on, were obtained to collect, organize, summarize, analyze and research.2. We collected and organized the post-operation follow-up data after UVA/Riboflavin crosslinking treating corneal ectasia after SMILE. The whole clinical data, including corneal topography, refraction, OCT, visual acuity and so on, were obtained to collect, organize, summarize, analyze and research.3. UVA/Riboflavin crosslinking treatment A lid speculum was placed into the fornix of the patient after local anaesthesia. The central corneal epithelium were removed. Starting 15 mins before the actual irradiation,0.1% ribof lavin hypotonic solution was dropped onto the cornea, until the cornea thickness reached 400μm in CXL group. Start the irradiation when the riboflavin has already entered the anterior chamber through slit lamp. The corneas were irradiated with a 365-nm UVA for 30 mins (irradiance 3 mW/cm2, dose 5.4 J/cm2) at a distance of 50mm from the corneal surface,0.1% riboflavin hypotonic solution was dropped onto the central corneal area every 2 mins.Results:1. Corneal topography revealed a corneal ectasia at month 6.5 after SMILE. Corneal anterior surface keratometry were 38.4/39.5 D and 38.6/40.8 D in right and left eye. Corneal posterior surface keratometry were-6.3/-6.8 D and -7.1/-6.6 D in right and left eye. Refraction was-1.00-0.75*42 and-1.25-0.75*134 in right and left eye.2. Corneal anterior surface keratometry at month 13 after SMILE were 39.8/42.0 D and 42.2/44.3 D in right and left eye, while posterior surface keratometry were -7.2/-6.5 D and -7.1/-6.6 D. Refraction was-3.25-1.50×41 and -4.50-1.25×132 in right and left eye.3. Corneal anterior surface keratometry at month 6 after UVA/Riboflavin crosslinking were 39.0/41.1 D and 40.3/42.1 D in right and left eye, while posterior surface keratometry were-6.9/-7.7 D and -7.7/-8.1 D. Refraction was -3.50-0.25*47 and -4.25-0.75*160 in right and left eye.Conclusion:1. A diagnosis of ectasia was made at month 6.5 after SMILE, and continued within a 13-month follow-up. This is the first report on patient with corneal ectasia after SMILE.2. This is the first case on patient with corneal ectasia after SMILE treated by UVA/riboflavin crosslinking, which was proved effective.