Three patterns for identifying the posterior plane of a lenticule during SMILE

PURPOSE: To describe three patterns of posterior plane edge identification in small-incision lenticule extraction and to prevent lenticule mis-dissection. METHODS: Femtosecond laser application was performed for small-incision lenticule extraction (SMILE) by one surgeon. The surgical videos of SMILE were recorded and re-watched by the surgeon after operation. RESULTS: Small-incision lenticule extraction was performed in 52 eyes of 28 patients, and no patient had cap-lenticular adhesion. Three patterns of posterior plane of lenticule were noticed when the surgical videos were re-watched. A “double lines” attached to the dissector were visible, signifying the reflective tape of the edge of the lenticule and the cap. During the expansion of the posterior lamellar separation, a fusiform opening between the lenticule edge and the underlying matrix layer was assumed to be a “leaf sign.” With some unintentional operation, the posterior lamella was pushed away from the surgeon. The edge of the lenticule away from the anatomical part, the marking of the femtosecond laser cut, and the edge of the cap layer showed three reflective bands, which formed a “triple lines.” The “double lines,” “leaf sign,” and “triple lines” were observed in 30 eyes (57.7%), 21 eyes (40.4%), and 1 eye (1.9%), respectively. CONCLUSION: These three signs cover possible situations and provide visual landmarks to identify the correct dissection of the posterior plane, which can help shorten the learning curve of novice doctors.