| gospa68@aol.com 2005-03-19, 6:22 pm |
| Confusion over Lasik eye surgery terminology
Posted By: News-Medical in Medical Procedure News
Published: Monday, 20-Dec-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/
|