暂无摘要。

OBJECTIVE: 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.
CONCLUSIONS: 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.

UNASSIGNED: To investigate potential risk factors for unintended initial dissection of the posterior plane in the initial learning curve of small incision lenticule extraction (SMILE).
UNASSIGNED: Data were derived from consecutive 263 eyes of 136 patients who underwent SMILE at the beginning of the surgeon\'s learning curve. Probabilities of unintended initial dissection of the posterior plane in left and right eyes were analyzed. Preoperative sphere, cylinder, spherical equivalent (SE), J0, J45, lenticular diameter, lenticular thickness, corneal thickness, and axial length were assessed between eyes in which posterior plane dissection was unintended and those in which it was not.
UNASSIGNED: Unintended initial dissection of the posterior plane occurred in 29 eyes, corresponding to an incidence rate of 11.03%. The probability of difficulty in plane dissection in the left eye was significantly higher than that in the right eye (P=0.003). Significant differences were found in sphere (T =2.8, P=0.006), SE (T =2.37, P=0.019), J0 (T =2.05, P=0.043) and axial length (T =-2.79, P=0.006) between eyes with and without unintended initial dissection of the posterior plane.
UNASSIGNED: In the present study, difficulty in plane dissection during SMILE was encountered significantly more often in left eyes for a right-hand doctor, and in eyes with low SE or high J0 values. Special attention should be paid to prevent unintended initial dissection of the posterior plane in such situations.

We introduce a novel focus shaping concept for intrastromal corneal dissection that facilitates cleavage along corneal lamellae, and we analyze laser-tissue interactions governing cutting effectiveness and mechanical side effects.
Focus shaping was achieved by a spiral phase plate that converts an incident Gaussian beam into a Laguerre-Gaussian beam with a helical phase. Such vortex beams have zero intensity at their center, are propagation invariant, and possess a ring focus equal in length to the Gaussian focus but with a larger diameter. Cutting precision and the required absorbed energy for flap dissection were compared for Gaussian and vortex beams on ex vivo porcine corneal specimens at pulse durations between 480 fs and 9 ps. Cutting quality and bubble formation were characterized by scanning electron microscopy and macro photography.
With the vortex beam, the cuts were much smoother. Bubble formation was markedly reduced because cutting can be performed close to the bubble threshold, whereas with the Gaussian beam energies well above threshold are needed. Although the incident energy at the flap dissection threshold was slightly larger for the vortex beam, the absorbed energy was much smaller and contributed more effectively to cutting. This reduced plasma-induced pressure more than sevenfold.
The vortex beam approach for corneal dissection is a simple, versatile, and cost-effective way of improving the precision of refractive surgery while reducing bubble formation and pressure-related mechanical side effects.
Phase plates for propagation invariant vortex beams are easily implemented in the beam path of next-generation clinical devices.