Confusion over Lasik eye surgery terminology

Dec 20 2004

The Eye Surgery Education Council of the American Society of Cataract and Refractive Surgery Foundation today issued a clarification on the use of the terms "wavefront-guided," and "wavefront-optimized" in connection with laser-based procedures (LASIK, PRK, etc.) and implantable lenses used for vision correction purposes. This clarification is issued to help patients make better-informed decisions regarding their eye care.

Wavefront-guided vision correction procedures customize laser treatments based on the individual characteristics of the eye that is being corrected. The term "wavefront-optimized" refers to laser treatment software that has been designed with certain corrections pre-programmed, although a true and customized wavefront plan is not employed.

The advent of wavefront technology enables ophthalmologists to measure and treat the defects of the eye's visual system that extend beyond what can be corrected by the basic prescription for eyeglasses or contact lenses. In addition, wavefront concepts are now being used in the design of artificial lenses that are implanted into the eye as part of treating cataracts and other vision problems.

Conventional vs. Wavefront

Conventional diagnostic systems and the treatment software that operates the lasers, rely upon the same kind of data that would be gathered during the physical examinations and ophthalmic tests used to make prescription eye glasses and contact lenses.

By contrast, the most commonly used wavefront technology passes light into the eye, reflects it off the inside of the back of the eye, and then measures how this light is distorted as it exits. All of the light rays that exit the eye form the wavefront, which is representative of the eye's focusing characteristics. This reflected light or wavefront is analyzed by computer software for distortions caused by the eye's optical imperfections. For laser-based vision correction procedures, that information is then used to generate a customized treatment plan that guides the laser as it treats the individual eye in question.

Wavefront-guided vs. Wavefront-optimized

"Spherical aberration" is a common optical imperfection that is treatable by wavefront technology. It occurs when the peripheral portion of a lens system focuses light to a different point than does the central part of the lens system. A patient with excessive spherical aberrations may have problems with glare and lack of sharpness of vision, particularly under dim light conditions. This problem is well known in the optical industry, and fine cameras, movie projectors, telescopes, etc., have been designed to overcome the problem.

Since spherical aberration is a common problem, some new laser programs have a built in software correction for it. Similarly, new artificial lenses (used for cataract and other vision correction procedures) are designed to correct for spherical aberration. Because the design or treatment concept has been influenced by wavefront methods, it has been referred to as wavefront- optimized, although a true and customized wavefront plan is not employed.

Vision correction surgery (LASIK, LASEK, PRK, etc.) to correct nearsightedness and farsightedness with or without astigmatism has become widely accepted. Approximately 655,000 people are expected to have laser- based and lens-based procedures in 2004. Customized, wavefront-guided laser procedures are more expensive than traditional ones, and differ from wavefront-optimized procedures. Patients considering laser-based and lens- based vision correction can benefit from understanding those differences.

The American Society of Cataract and Refractive Surgery is an international educational and scientific organization whose 9,000 member ophthalmologists specialize in surgical procedures associated with the front part (anterior segment) of the eye. They specialize in treating cataracts, glaucoma, diseases and trauma of the cornea, and pediatric eye disorders, and in vision correction procedures using laser-based and artificial lens technologies. The Society publishes the peer-reviewed Journal of Cataract and Refractive Surgery.

http://www.ascrs.org/