Guiding The Treatment of Anterior Eye Diseases with Optical Coherence Tomography

描述(申请人提供)：该项目的长期目标是利用最新可用的超高速光学相干断层扫描(OCT)技术来指导前部眼部疾病的手术治疗。测量角膜光学表面的像差需要很高的精度。OCT以其精致的空间分辨率而闻名，但直到最近，它还没有足够的速度来克服眼睛固有的生物运动并捕捉到角膜的形状。傅立叶域(FD)OCT技术的发展使所需的速度成为可能。具体目标是：(1)研制一种超高速前段OCT检测仪。一套能够进行每秒26,000次轴向扫描、分辨率为5-5米的FD-OCT系统已经过测试。初步数据表明，它能够以1-5m均方根的精度绘制角膜厚度图，以0.2屈光度的精度测量角膜屈光度。将开发运动校正算法，以进一步提高精度。(2)发展OCT引导下的角膜激光手术治疗不规则混浊的角膜。虽然波前传感和Placido-Ring地形图已经被用于指导激光角膜手术，但它们往往无法对不规则的角膜进行有效的测量。我们的初步结果表明，OCT可以可靠地对这些最需要手术治疗的病变角膜进行测量。OCT系统获得的角膜厚度或地形图将用于编程飞秒激光角膜解剖和准分子激光消融的深度。OCT引导的飞秒激光板层角膜移植和准分子激光治疗性角膜切削术(PTK)将在兔研究中进行测试。对角膜手术后有角膜瘢痕、扩张、营养不良或不规则散光的患者进行扫描，并用计算机模拟激光手术以评估视力结果。模拟将考虑测量的可变性、激光传输误差、愈合效果和视觉光学。这些测试将为未来的人体试验做准备。(3)建立基于OCT的人工晶状体屈光度公式。对于有过激光矫正视力的患者来说，人工晶状体的选择是困难的，通常会导致白内障手术后明显的近视或远视。激光消融改变了角膜前后表面之间的自然关系，在传统的角膜屈光度测量和人工晶状体计算中造成误差。这一日益普遍的问题可以通过使用OCT测量角膜前后屈光度来解决。基于OCT的人工晶状体配方将在临床试验中进行测试。该项目的目的是开发一种使用超高速高分辨率光学相干断层扫描(OCT)系统对角膜进行成像的方法，该系统将精确地测量角膜厚度和形状，并使用这些信息来指导眼科手术。形状不规则或有疤痕的患者可以通过结合OCT和激光的精度来重塑角膜来恢复视力，而不是传统的角膜移植，这与视力恢复缓慢和移植排斥反应的风险有关。以往接受过激光矫正的白内障患者往往会出现明显的近视或远视，这一问题可以通过使用基于OCT测量角膜屈光度的更准确的人工晶状体度数选择公式来解决。

DESCRIPTION (provided by applicant): The long-term goal of this project is to utilize newly available very high-speed optical coherence tomography (OCT) technology to guide surgical treatments of anterior eye diseases. Measuring aberrations in the optical surfaces of the cornea requires great precision. OCT is well known for its exquisite spatial resolution, but until recently it has not had sufficient speed to overcome the inherent biological motion of the eye and capture the shape of the cornea. The development of Fourier-domain (FD) OCT technology has made the requisite speed possible. The specific aims are: (1) To develop a very high-speed anterior segment OCT instrument. An FD-OCT system capable of 26,000 axial scans/second and 5-5m resolution has been tested. Preliminary data show that it is able to map corneal thickness with a precision of 1-5m root-mean-square and measure corneal power with a precision of 0.2 diopters. Motion correction algorithms will be developed to further improve the precision. (2) To develop OCT-guided corneal laser surgery for the treatment of irregular and opacified corneas. Although wavefront sensing and Placido-ring topography have been used to guide laser corneal surgeries, they are often unable to make valid measurements of irregular corneas. Our preliminary results showed that OCT can reliably make measurements in these diseased corneas that are most in need of surgical remedy. Corneal thickness or topography maps obtained by the OCT system will be used to program the depth of femtosecond laser corneal dissection and excimer laser ablation. OCT-guided femtosecond laser lamellar keratoplasty and excimer laser phototherapeutic keratectomy (PTK) will be tested in rabbit studies. Patients with corneal scar, ectasia, dystrophy, or irregular astigmatism following corneal surgery will be scanned, and laser surgery will be simulated by computer to evaluate the visual outcome. The simulation will take into account measurement variability, laser delivery error, healing effects, and visual optics. These tests will prepare for future human trials. (3) To develop an OCT-based intraocular lens (IOL) power formula. IOL power selection is difficult in patients who have had previous laser vision correction, often resulting in significant near- or far-sightedness after the cataract surgery. Laser ablation alters the natural relationship between the front and back corneal surfaces, causing error in conventional keratometry and IOL calculation. This increasingly common problem could be solved by measuring both anterior and posterior corneal powers with OCT. The OCT-based IOL formula will be tested in a clinical trial. The aim of this project is to develop methods for imaging the cornea with a very high-speed and high-resolution optical coherence tomography (OCT) system that will precisely measure corneal thickness and shape and use this information to guide eye surgery. Patients with irregularly shaped or scarred corneas could have their vision restored by reshaping the corneas with a procedure that combines the precision of OCT and lasers instead of traditional corneal transplantation, which is associated with slow visual recovery and risks of transplant rejection. Cataract surgery in patients with previous laser vision correction often leads to significant near- or far-sightedness, a problem that could be resolved by using a more accurate intraocular lens power selection formula based on the measurement of corneal refractive power with OCT.