Corneal Remodeling After Myopic SMILE: An Optical Coherence Tomography and In Vivo Confocal Microscopy Study

To study corneal remodeling during the first 6 months after myopic small incision lenticule extraction (SMILE) with a 10% overcorrection nomogram, by spectral-domain optical coherence tomography (SD-OCT) and in vivo confocal microscopy (IVCM).

This prospective non-randomized observational study included 60 eyes from 30 patients treated by SMILE for low to moderate myopia. A 10% overcorrection nomogram was applied for all eyes. Epithelial and corneal thickness maps were obtained within the central 6 mm, by SD-OCT, at each visit. Lenticule thickness was calculated by subtracting the postoperative central stromal thickness from the preoperative central stromal thickness. IVCM was performed at each visit.

The mean surgical refractive correction was -3.99 ± 1.50 diopters (D) before and -0.09 ± 0.37 D after surgery. Central epithelial thickness increased from 53.7 ± 4.0 to 57.1 ± 4.1 µm at 6 months after SMILE (P < .001). The measured lenticule thickness was 16 ± 6.1 µm less than the programmed lenticule thickness (P < .001). Both central epithelial hyperplasia and the mismatch between measured and programmed lenticule thickness were positively correlated to the degree of myopia (r² = 0.60, P < .001 and r² = 0.47, P < .001, respectively). Fibrosis at the interface was not correlated with epithelial thickening (r² = 0.06, P = .29) or lenticule thickness error (r² = 0.07, P = .22).

Both epithelial thickening and the mismatch between the targeted and achieved lenticule thickness resulted in a slight undercorrection with a 10% overcorrection nomogram in low and moderate myopia. Fibrosis at the interface was not responsible for lenticule thickness error. Additional overcorrection is required to increase accuracy. [J Refract Surg. 2020;36(9):597-605.].