Ito M, Quantock A J, Malhan S, Schanzlin D J, Krueger R R
Anheuser-Busch Eye Institute, Department of Opthalmology Saint Louis University School of Medicine, MO 63104, USA.
J Refract Surg. 1996 Sep-Oct;12(6):721-8. doi: 10.3928/1081-597X-19960901-16.
Excimer laser in situ keratomileusis requires a microkeratome to generate an anterior corneal flap, plus an excimer laser to ablate the underlying stromal tissue. In this paper we introduce the concepts of laser flap formation and in situ keratomileusis using a picosecond laser.
A neodymium-doped yttrium-lithium-fluoride (Nd:YLF) laser with a plano-plano quartz applanation lens was used to generate various patterns of intrastromal photodisruption in human donor eyes to fashion anterior corneal flaps and generate intrastromal lenticules.
Smooth intrastromal dissections, 6 mm in diameter, were generated 160 microns below the corneal surface when the laser delivered pulses at 1 kHz with energies of either 40 microJ/pulse or 60 microJ/pulse, placed 20 microns apart in an expanding spiral. This enabled us to fashion anterior corneal flaps. The ease of the surgery and quality of the dissection corresponded well, and it was evident that both deteriorated noticeably when the laser pulses were separated by 25 microns or 30 microns, regardless of pulse energy. Using 40 microJ laser pulses placed 20 microns apart we also created a 5-mm diameter, 320 microns thick (130 microns-450 microns deep) stromal lenticule below a corneal flap that was easily extracted when the flap was raised.
Anterior corneal flaps were easily fashioned using a Nd:YLF laser. Picosecond laser in situ keratomileusis with a Nd:YLF laser could offer a favorable alternative to combined microkeratome/excimer laser in situ keratomileusis.
准分子激光原位角膜磨镶术需要使用微型角膜刀制作角膜前瓣，再用准分子激光消融下方的基质组织。在本文中，我们介绍了使用皮秒激光制作激光瓣和原位角膜磨镶术的概念。
使用一台带有平-平石英压平透镜的掺钕钇锂氟化物（Nd:YLF）激光，在人供体眼内产生各种基质内光致破裂模式，以制作角膜前瓣并生成基质内透镜。
当激光以1kHz的频率发射脉冲，能量为40微焦/脉冲或60微焦/脉冲，脉冲间隔20微米并呈扩展螺旋状排列时，在角膜表面下方160微米处产生了直径为6毫米的平滑基质内切割。这使我们能够制作角膜前瓣。手术的简易程度和切割质量良好匹配，并且很明显，当激光脉冲间隔为25微米或30微米时，无论脉冲能量如何，两者都会明显变差。使用间隔20微米的40微焦激光脉冲，我们还在角膜瓣下方制作了一个直径5毫米、厚320微米（深130微米 - 450微米）的基质内透镜，当掀起角膜瓣时很容易取出。
使用Nd:YLF激光可轻松制作角膜前瓣。Nd:YLF激光皮秒原位角膜磨镶术可为微型角膜刀/准分子激光联合原位角膜磨镶术提供一种良好的替代方法。
