Femtosecond Laser Posterior Lamellar Keratoplasty

描述（由申请人提供）：内皮细胞层功能障碍导致角膜增厚，最终导致角膜透明度丧失。目前，穿透性角膜移植术被广泛应用于病变内皮的替代。该手术的缺点包括角膜高度散光，各种缝合并发症和脆弱的移植物-宿主连接处易导致伤口开裂。后板层角膜移植术，只替换病变的内皮和少量的descemet前基质，可以避免这些问题，然而，使用传统手术器械的手术难度限制了这些手术的使用，只有极少数技术高超的外科医生才能使用。新型飞秒激光手术技术能够实现高精度的角膜切除术，对邻近组织的附带损伤在临床上可以忽略不计，并且在角膜前表面没有开放切口或损伤。飞秒激光能量可以通过透明和半透明角膜传递，并聚焦在角膜前表面下的任何深度。组织切除是通过沿角膜基质内的预定模式扫描飞秒激光的焦点来实现的。一层微气泡是由飞秒光破坏产生的，它分离了组织。该技术目前已被FDA批准用于角膜瓣切割和角膜前移植。

DESCRIPTION (provided by applicant): Malfunction of the endothelial cell layer results in corneal thickening, and eventually the loss of corneal transparency. Currently, penetrating keratoplasty is widely used to replace the diseased endothelium. Disadvantages of the procedure include high corneal astigmatism, sundry suture complications and a weak graft-host junction that is susceptible to wound dehiscence. A posterior lamellar keratoplasty, which replaces only the diseased endothelium and a modicum of pre-Descemet's stroma can avert these problems, however, the difficulty of surgery using traditional surgical instruments limits the use of these procedures to a very few highly skilled surgeons. Novel femtosecond laser surgical technology is capable of creating high precision corneal resections with clinically negligible collateral damage to adjacent tissue and without opening cuts or damage at the anterior corneal surface. Femtosecond laser energy can be delivered through transparent and semitransparent cornea and focused at any depth beneath the corneal anterior surface. Tissue resection is achieved by scanning the focal spot of the femtosecond laser along a predetermined pattern inside the corneal stroma. A layer of microbubbles is created by femtosecond photodisruptions, which separates the tissue. The technology is now FDA cleared for cutting corneal flaps and anterior corneal grafts. We propose to develop new procedures to replace the diseased endothelial cell layer using femtosecond laser to cut posterior corneal grafts in both the donor and host corneas. Novel host-donor tissue contact geometries, including self-locking wound edges, are predicted to enhance wound healing. Diseased posterior cornea is removed through a small side incision at the limbus. The donor graft is inserted into the lamellar interface through the same incision and held in position with air injected into the anterior chamber. To optimize refractive outcomes and self-locking or self-sealing wound edges we propose to model the biomechanics of the postoperative cornea and confirm these results with in vivo animal experiments. Finally, we propose in vivo experiments in animals with non-regenerating endothelium to study the physiology and biomechanics of the postoperative corneas as a function of graft geometry and time. Successful completion of this project will contribute to the understanding of corneal biomechanics and physiology after femtosecond laser posterior lamellar keratoplasty. The project introduces a precision microsurgical technique for replacing diseased endothelium with potentially accelerated recovery and improved visual outcomes.