波前像差及其在眼科学和视光学中的应用 

      自从1961年Smirnov首次测量人眼波前像差以来，已有40年的历史，但是直到1996年快速而精确的测量仪器产生，波前像差技术才日趋引起人们的注意。目前，对眼科医生和视光学医师来说，波前像差的临床应用具有广泛的前景，但是，实现其应用的特殊技术尚处于初步研发阶段。

      在过去的两年里，波前像差技术在眼科的应用几乎都集中在屈光手术上。同PRK手术一样，LASIK术后像差的增加屡见报道。无论远视还是近视患者，屈光手术都引起了低阶和高阶像差的增加。为了尽可能的减少手术引起的像差增加和矫正患者原有的像差，在过去的两年里，波前像差引导的屈光手术已经有所开展，波前引导技术增加了对波前像差的矫正，但结果尚不能令人满意。基于对一些涉及到年龄、调节和色像差等问题的基础研究已经向我们提出了实现完美矫正的严峻挑战。现在尽管我们的技术远未达到实现完美矫正的境界，如何优化波前引导的屈光手术仍是一个非常重要的问题。

      自去年以来，人们已经观察到同正常眼相比白内障和青光眼术后眼的波前像差增加。今年亦发现行角膜切口和巩膜切口的白内障患者术后像差存在差别。这些结果提示手术有待改进，但相应的技巧还未实现。

      补偿光学和检眼镜的结合为眼科医生和视光学医师得到清晰的视网膜像带来了新的希望。目前这样一种装置已在一些实验室用于科学研究，但用于临床的这种仪器尚处于研制阶段。

      在视光学领域，最近人们正在研究像差测量和传统验光的关系。人们亦发现波前像差能为传统的屈光不正提供良好的预测。接触镜能够影响波前像差，但是不同类型的接触镜有不同的效应，对于近视眼，RGP接触镜能够减少低阶像差，而软性接触镜则能导致更大的像差，且主要为高阶像差。

       总之，波前技术在眼科和视光学的临床应用正在蓬勃发展，前景广阔。

Wavefront Aberration & its Applications in Ophthalmology and Optometry 

 Jichang He, MD, New England College of Optometry, Boston, USA

      Forty years have passed since wavefront aberration was first measured in the human eye by Smirnov in 1961.  Interest in wavefront aberration, however, did not accelerate until fast measurement with high precision was achieved in 1996.  Currently, there are high expectations for clinical applications of wavefront aberration for ophthalmologists and optometrists, but development of specific techniques to provide these expected applications is only in its infancy.

      The overwhelming emphasis of wavefront application in ophthalmology during last couple years has been focused on refractive surgery.  Elevated wavefront aberrations have been reported frequently in patients with LASIK as well as PRK.  The refractive surgery induced wavefront aberrations were observed in both myopia and hyperopia with both lower order aberrations and higher order aberrations.  With the aim of minimizing the induced aberrations and correcting the original aberrations for patients, wavefront guided refractive surgeries have been performed during last two years.  Improvement in controlling wavefront aberration was found with the wavefront guided techniques, but satisfaction has not yet been achieved.  Serious challenges to the benefits of a prefect correction with refractive surgery have emerged from scientific researches on the basis of problems dealing with aging, accommodation and chromatic aberrations.  Now, the question of how to optimize wavefront guided refractive surgery is a serious question, even though the technique is still far from reaching a perfect correction. 

Since last year, increased wavefront aberrations have been observed for patients with cataract and glaucoma surgeries in comparing with normal subjects.  Differences between post-operative wavefront aberrations for cataract patients with corneal incisions and those with scleral incisions have also been found this year.  Improvement of these surgeries is implied by these studies, but techniques for accomplishing such improvement have not yet been developed.  

Adaptive optics combined with the ophthalmoscope is a new hope for ophthalmologists and optometrists to obtain a better retinal image.  Even though such a system is currently available in the laboratory for scientific research, development of this type of instrument in clinical application has not yet been completed. 

In optometry, the relationship between wavefront measurement and conventional refractive testing has been recently examined.  Wavefront aberrations were found to provide a good prediction of the conventional refractive error.  Contact lenses were found to affect wavefront aberrations but have different effects with different types of contact lenses.  While soft contact lenses were found to induce more wavefront aberrations, mainly higher order aberrations, RGP contact lenses reduce lower order aberrations in the myopic eye.

Overall, clinical applications of wavefront techniques in both ophthalmology and optometry are now rapidly developing with increased exploration predictable in the near future.