Randomized Controlled Trial On Corneal Denervation, Neuroinflammation And Ocular Surface In Corneal Lenticule Extraction For Advanced Refractive Correction (Clear) And Small Incision Lenticule Extraction (Smile)

To investigate and compare the corneal denervation, tear neuromediators, and ocular surface changes following corneal lenticule extraction for advanced refractive correction (CLEAR) versus small incision lenticule extraction (SMILE).

Singapore National Eye Centre

In this randomized clinical trial, 19 patients were randomized to undergo CLEAR in one eye and SMILE in the other eye. Ocular surface assessments, in-vivo confocal microscopy for 7 corneal nerve parameters, 4 corneal dendritic cell parameters, 3 corneal epithelial parameters, and tear neuromediator analysis were performed preoperatively and 1, 3, 6 and 12 months postoperatively.  

There was no significant difference in all the ocular surface assessments between CLEAR and SMILE throughout the postoperative 1 year. CLEAR and SMILE led to significant and comparable reductions of corneal nerve fiber density (CNFD), nerve branch density, total branch density, nerve fiber length, area, and fiber fractal dimension, and these nerve metrics did not restore even at 1 year. The reduction in CNFD was significantly correlated with the corrected spherical equivalent in both surgical types. Both procedures presented similar trends in the changes in tear neuromediators, although post-SMILE eyes had significantly higher nerve growth factor concentrations at 1 month.  

CLEAR and SMILE had comparable effects on ocular surface, corneal denervation and postoperative neuroinflammation.