The excimer laser in ophthalmology: a state-of-knowledge update

Institut national d'excellence en santé et en services sociaux (INESSS)

ABSTRACT

INTRODUCTION:

Since the publication, in May 1997, of the Con-seil d'évaluation des technologies de la santé du Québec's previous report on the state of knowl-edge regarding excimer laser photorefractive keratectomy [60], the ophthalmologic applica-tions based on this means of intervention have continued to evolve at a rapid pace. Furthermore, these applications, which are available essen-tially in the private sector, given that they are services paid for directly by patients, have been diffused very rapidly in Québec and elsewhere. Our first objective in this report is to update the assessment of the benefits and drawbacks of photorefractive keratectomy (PRK) in light of the developments that it has undergone. Also, we examine the LASIK technique in considerable detail and assess its efficacy and complications in the treatment of myopia and hyperopia. After discussing patient satisfaction and optical quality of vision, we examine the indications and contraindications of PRK and LASIK and the criteria for choosing between the two proce-dures. We also look at the alternatives, future developments and research in this field. Lastly, we provide a recap and discussion, then, in a separate section, put forth a number of specific and general conclusions concerning the applica-tions of the excimer laser. For practical reasons, the general principles of excimer laser refractive surgery, which were ex-plained in the first report, are explained again in Appendix A. Also, a brief summary of ocular anatomy and the main refractive errors is repro-duced in the following section to make this re-port easier to understand by readers who might be less familiar with ophthalmology.

METHODOLOGY:

The present report provides an update on refractive surgery since the publication of the 1997 report. A MEDLINE search was done for titles of arti-cles published from 1995 up to and including October 1999 with the keyword "excimer". All the abstracts thus obtained were reviewed. The full articles chosen were then obtained and ex-amined. This literature review was limited by the availability of the articles and the language in which they were written. Only those articles written in English or French were selected. Not all the articles examined are cited or mentioned in this report.

CONCLUSION:

The purpose of this report was to provide an up-date on the scientific knowledge concerning the efficacy and safety of excimer laser photorefrac-tive keratectomy for the correction of myopia (with or without astigmatism) and hyperopia. The discussion concerned both the "traditional" approach, PRK, and a more recent approach, LASIK. From its systematic analysis of the scientific lit-erature published between 1995 and October 1999, CETS concludes that PRK and LASIK can now be considered "accepted" technologies for the treatment of mild and moderate myopia, al-though there is a lack of long- term follow-up. Also, LASIK can be considered an "innovative" technology for the correction of severe myopia and of hyperopia. The treatment of these condi-tions by LASIK therefore requires tighter control to prevent premature widespread use. Although it did not provide a systematic assess-ment of them, the report did mention other alter-natives and future developments concerning vi-sion correction, such as lens removal, phakic intraocular lenses and intracorneal rings. These technologies are still considered "experimental" and, as such, should be made available to pa-tients only in the context of a research project.

INTRODUCTION:

METHODOLOGY:

CONCLUSION:

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