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Recent Progress of Laser and Non-laser Vision Correction |
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| Recent Progress of Laser and Non-laser Vision Correction |
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作者：J. T. Li… 文章来源：4532 Old Carriage Trail Oviedo, FL 32765 U.S.A.Tel: (407) 699-4540, Fax: (407) 699-0471 点击数：2218 更新时间：2004/6/25 
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| Purpose: To review and update the recent development of methods for vision corrections and compare their advantages.
Method: Technologies used for vision corrections include LASIK, LASEK, LTK, DTK and CK for myopic and hyperopic treatment, multi-focal and accommodative IOL, scleral band expansion (SBE) and the most recent LAPR (laser presbyopia reversal) for presbyopia treatment via improvement of accommodation amplitude (A). We propose a 3-component theory to analyze A consisting of axial movement, lens thickness and radius change. The elastic-mechanism and soft-tissue refilling effect are proposed. The lasers used for vision correction include UV and IR lasers at (193-212) nm and (1.9-2.1) um, 2.94 um which cover both ablative and thermal effects to reshape the corneal surface or alter the sclera-ciliary properties. Comparing features of LASIK vs. LASEK, LTK-DTK vs. CK, SEB vs. LAPR, multi-focal vs. accommodative IOL will be presented by the principles and clinical aspects of each method. Supervision for customized correction using wavefront technology and our newly developed Gaussian optics theory that includes all the 7 ocular parameters. Many new concepts and formulas will be presented to improve treatment accuracy. The clinical key issues of efficacy, safety, complication and regression will be analyzed by tissue response to lasers or implanted IOL or SEB.
Results: Vision corrections for patient, with age (18 to 44) and (45 to 65) are possible via the combined technologies of corneal reshaping (surface ablation or surface thermal shrinkage), lens reshaping (natural lens relaxation or implanted IOL) and ocular image measurements (such as A-scan, keratometer, UBM and wavefront). Customized treatment or retreatment for irregular visions is also possible via the flying-spot (or scanning) laser integrated with an eye tracking and characterized by wavefront analysis. Multi-zone LASIK and implanted IOL are designed for high diopter corrections, whereas accommodative IOL, LAPR and SEB are used for accommodation of (1.5 to 3.0) diopter, which may also be applied to post-LASIK or post-cataract patients. Pharmological means may also enhance these surgical methods, such as the use of pilocarpine pre- or post-operatively. However, each of the surgical method has certain limitations resulted from regression, in particular.
Conclusion: We present various lasers and non-laser methods that make vision corrections possible and covering age range of 18 to 65. Customized correction and supervision are also achievable via modern imaging devices and a scanning laser with eye tracking. Accommodation restoring or presbyopia reversal is possible when the elasticity of the ciliary sclera-zonus complex may be alternated via surgical methods.
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