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LASIK
Eye Surgery Information to help the
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Wavefront - guided lasers - Many excimer lasers are connected to a device that detects and "maps" defects in the eye's optical system, based on how light waves travel through the eye. These wavefront devices individually guide the way the eye's cornea is reshaped to achieve a custom ablation.
Excimer Lasers and Eye Tracking
Most modern excimer lasers now have automated eye tracking
systems to keep the laser beam on target. Studies have demonstrated
that eye trackers produce better outcomes, compared with lasers that
in the past did not use eye tracking systems.
Indications and Features of Excimer Lasers
In the following chart, OZ stands for optical zone, meaning the
maximum size of the pupil allowing light to pass through the eye
that can effectively be targeted for correction
with a specific laser. TZ stands for the maximum treatment area, including a
transition zone that can be used in an ablation to achieve vision
correction in the targeted area.
Modern FDA - Approved Excimer Lasers
| Model | Indication | Type of Laser Beam |
Optical
Zone (OZ) and Treatment Zone (TZ) |
FDA Approval Year |
|---|---|---|---|---|
|
Alcon
LADARVision 4000 & CustomCornea (laser plus wavefront device to guide laser) |
Myopia: up to -8.00 D with or without astigmatism (up to -4.00 D) Hyperopia and hyperopic astigmatism: up to +5.00 D (near vision problems) and astigmatism causing distance vision problems up to -3.00 D |
Scanning spot (0.8 mm) |
OZ:
5.5 mm TZ: 7.5 mm |
2002 (myopia with or without astigmatism) 2006 (hyperopia and hyperopic astigmatism) |
|
Alcon LADAR6000
& CustomCornea (laser plus wavefront device to guide laser) |
Same as LADARVision 4000 | Same as LADARVision 4000 |
OZ:
6.5 mm TZ: 9.0 mm |
2006 (flexible platform and faster than previous models) |
|
Bausch & Lomb
Technolas 217A
and
Technolas 217z Zyoptix (laser plus wavefront device to guide laser, approved 2003) |
Myopia: up to
-12.00 D with or without astigmatism (up to -3.00 D) Hyperopia: up to +4.00 D with or without astigmatism (up to +2.00 D) |
Scanning spot (2.0 mm) |
OZ:
6.0 mm TZ: 7.0 mm |
2000 (myopia from -1.00 to -7.00 D) 2002 (myopia up to -11.00 D) 2003 (hyperopia with or without mixed astigmatism) |
| Carl Zeiss Meditec MEL 80 |
Myopia: up to -7.00
D with or without astigmatism (up to -3.00 D) |
Scanning
spot
(0.7 mm) Gaussian profile with more energy applied centrally |
OZ:
6.0 to 7.0 mm TZ: 7.7 to 8.9 mm |
2006 (myopia with or without astigmatism) |
| Nidek EC-5000 |
Myopia: -1.00 to
-14.00 D with or without astigmatism (less than 4.00 D) Hyperopia: +0.50 to +5.00 D and up to +2.00 D astigmatism |
Scanning slit (7.0 x 2.0 mm) |
OZ:
5.5 mm TZ: 7.0 mm |
2000 (myopia from -1.00 to -14.00 D) 2006 (hyperopia and hyperopic astigmatism) |
|
Visx Star S4
& WaveScan WaveFront System (laser plus wavefront device to guide laser) |
Myopia: up to -6.00
D with or without astigmatism (up to -3.00 D) |
Variable
scanning
spot beam (0.65 mm to 6.5 mm) |
OZ:
4.0 to 9.0 mm TZ: 4.5 to 9.5 mm |
2003 |
|
Visx Star S4 IR
& CustomVue
(laser plus wavefront device to guide laser) |
Myopia: up to -6.00
D with or without astigmatism (up to -3.00 D) Hyperopia: up to +3.00 D and up to +2.00 D of astigmatism Mixed astigmatism: up to 5.00 D |
Same as S4 |
OZ:
6.0 mm TZ: 9.0 mm |
2005 |
| WaveLight Allegretto Wave |
Myopia: up to
-12.00 D with or without astigmatism (up to -6.00 D) Hyperopia: up to +6.00 D with or without astigmatism (up to +5.00 D, not exceeding mean spherical equivalent or total refractive error of +6.00 D) Mixed astigmatism: up to 6.00 D |
Scanning spot beam (0.95 mm) with emphasis on applying more energy centrally (Gaussian profile) |
OZ:
4.5 to 8.0 mm TZ: 5.2 to 8.7 mm for spherical treatments; 7.0 to 9.0 mm for cylindrical and spherico- cylindrical treatments |
2003 (myopia and hyperopia) 2006 (mixed astigmatism) |
| WaveLight Allegretto Wave With Allegro Analyzer (laser plus wavefront device to guide laser) |
Myopia: up to -7.00
D with or without astigmatism (up to 3.00 D) Mixed astigmatism: up to 6.00 D |
Same as Allegretto Wave |
OZ:
Same as
Allegretto
Wave TZ: Same as Allegretto Wave |
2006 2007 (mixed astigmatism) |
| Notes: "D" is an abbreviation
for "diopters." While FDA approval is based on studies with these levels of diopters, individual doctors are free to use their own discretion in deciding what is best for their patients. For example, a doctor may choose to use a laser for a patient whose vision falls outside the above ranges, or may decide against using any laser on a patient with -13.50 diopters of myopia, even though some are approved for up to -14.00. It is important that patients and doctors discuss the risks and benefits before surgery is performed. |
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