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Milestones in the Field
of Refractive Surgery
Early
1970’s: Radial Keratotomy (RK), a precursor to laser
refractive surgery, was initially developed by accident to
decrease nearsightedness. During the procedure, radial incisions
are made in the mid-periphery of the cornea with a precise
diamond blade set to a particular depth. The number of incisions
and their location is determined by the degree of nearsightedness.
These incisions allow the sides of the cornea to bulge outward
and thereby flatten the central portion of the cornea. This
brings the focal point of the eye closer to the retina and
improves one's distance vision. RK was brought to the US in
the late 70’s
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Automated Lamellar
Keratoplasty (ALK) uses a device called a microkeratome to
remove a thin slice of the cornea from the eye to reshape
it for corrected vision. In this procedure, the eye is anesthetized
and a ring is fixed to it in order to keep it properly positioned
and flat. The microkeratome is then makes a small incomplete
flap across the cornea by cutting across it. While still attached
at one side, the corneal flap is folded back to reveal a sub
layer of cornea. At this point, the microkeratome is precisely
readjusted to match the calculated cut depth for the patient's
vision correction. The calculation is based on the patient's
glasses and contact lens prescriptions. The surgeon then passes
the microkeratome completely over the eye making the power
cut. After the power cut, the corneal flap is laid back over
the eye where it reattaches. |
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Astigmatic
Keratotomy (AK) is a surgical procedure used to decrease astigmatism.
This procedure can be used in combination with radial keratotomy
and excimer laser vision correction. During astigmatic keratotomy,
a diamond blade set to a precise depth makes a circumferential
incision in the cornea. The incision causes the cornea to
assume a more spherical shape and decreases the degree of
astigmatism. |
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1987: Photorefractive
Keratectomy (PRK) utilizes a type of laser called an excimer
laser to decrease nearsightedness. This form of laser vision
correction removes a precise amount of tissue using a "cold"
ultraviolet laser. The laser utilizes a sophisticated computer
program that calculates and removes a precise amount of tissue
from the center of one's cornea to decrease its curvature.
This change in the cornea brings the focal point of the eye
closer to the retina and improves one's distance vision. The
Blum patent was issued November, 1988. |
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1991: LASIK
is a shortened term standing for "LAser in SItu Keratomileusis".
This correction procedure utilizes two devices to alter the
degree of near-sightedness in an eye. These two devices are
the excimer laser and the microkeratome. After anesthetic
eyedrops are put on the eye, a suction ring is centered over
the cornea of the eye. This suction ring stabilizes the position
of your eye and increases the pressure to a level that is
needed for proper functioning of the microkeratome. The guide
tracks on this suction ring are used to provide a precise
path for the microkeratome. |
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Both PRK
and LASIK were first used with broad beam lasers, an inferior
technological to scanning, small beam lasers. Scanning refractive
surgery is defined by the issuance of the Lin patent in May,
1996, though LaserSight was producing systems internationally
since 1994. |
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Both PRK and LASIK were
first used with broad beam lasers, an inferior technological
to scanning, small beam lasers. Scanning refractive surgery
is defined by the issuance of the Lin patent in May, 1996,
though LaserSight was producing systems internationally since
1994.
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Late 1990’s: In the late 90’s, topography-driven
refractive surgery was developed. The concept of how this
is used is still a matter of debate because it’s not
clear amongst the companies how everyone utilizes the topography.
The general theory, however, is that the topography of the
anterior surface is used to generate a custom ablation profile
for that patient, usable in PRK, LASIK, or similar procedures
(such as transepithelial PRK).
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| Early 2000’s: The new millennium saw
the introduction of wavefront-driven refractive laser surgery.
Like with topography-driven surgery, it’s unclear how
different competitors use the data from the wavefront devices.
Also, the custom ablation profile is performed using the treatment
modality preferred by the surgeon. |
| 2003: Ellipsoidal surgical planning was formally
released in January, 2003 with the introduction of AstraPro
and is the current state-of-the-art of laser refractive surgery,
especially considering it’s improvements in the 2006 release. |
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