PRK (Photorefractive Keratectomy)
PRK LASIK is a refractive surgery in which the central epithelium, or surface layer of the cornea, is removed by the surgeon, and then the corneal bed is directly reshaped with the laser. PRK is generally used for patients whose corneas are too thin to allow for the creation of the LASIK flap safely. If you are having PRK, it likely means your corneas are thinner than average, your prescription is higher or both.
During PRK LASIK corrective surgery the outer layer of the cornea, the epithelium, is removed centrally. The laser is then directly applied to the underlying cornea. During this procedure, your surgeon may choose to use an anti-inflammatory compound called Mitomycin C on some patients. Mitomycin C is a powerful pharmaceutical agent which inhibits haze in patients following PRK surgery. It is highly recommended to use Mitomycin C on all patients with greater than -4.00 D prescriptions who are having PRK, since these patients are at greater risk of the complication of haze formation post operatively.
Following laser vision correction, a bandage lens is then placed on the cornea to assist in healing of the operative area and for patient comfort. Healing typically takes 4-7 days. While the bandage contact lens is in place, visits to our clinic are recommended every day or every other day to monitor healing.
After the bandage contact lens is removed, follow-ups are usually preformed 1 week, 1 month, 3 months, and 6 months post-operatively. With PRK LASIK no corneal flap is created, therefore restrictions with physical activities are less than what is imposed upon LASIK patients.
LASIK (Laser In-Situ Keratomileusis)
The first step with LASIK Surgery is to have a thin corneal flap made to reveal the tissue that will be reshaped to correct your refractive error. There are two main methods used to create a corneal flap; the microkeratome, which uses a metal blade, or the Femtosecond laser which allows the flap to be created without the use of a blade.
At LASIK Provision we are currently utilizing the VisuMax Femtosecond Laser (bladeless method). In creating the flap, a hinge area is created at the twelve o’clock position, which allows the surgeon to lift the flap and to reshape the exposed cornea.
Femtosecond Laser Technology (VISUMAX)
A state-of-the-art excimer laser is used to reshape the cornea, removing a precise amount of corneal tissue from the exposed corneal bed. The pre-operative examination determines the power of your eye, which enables us to calculate the amount of tissue to be removed. Recent prescriptions for your glasses or contact lenses are usually very close to these measurements.
The flap is then laid back into its original position, and within minutes natural bonds secure it to the cornea. The epithelium, or surface layer of the cornea, begins to grow over the cut flap edge within a few hours, sealing the flap into position. Collagen bonds start to form within the cornea and around the edge of the flap within days.
Healing is rapid with most cases requiring four follow-up visits (1 day, 1 week, 1 month, 3 months). A requirement of this procedure is that the corneal thickness is sufficient for the creation of the flap and laser ablation while maintaining a safe residual corneal bed of 250 microns.
Femtosecond Laser Technology (VISUMAX)
Carl Zeiss has over 160 years of experience in the development of optics. ZEISS high performance optics is the key to providing the best corneal flap. In general, patients who qualify for LASIK are also candidates for the VisuMax Laser corneal flap treatment, and thus will benefit from its accuracy and gentleness.
Gentle Treatment
Flap creation with the VisuMax is a completely bladeless procedure. The creation of the corneal flap with the VisuMax is very fast and takes approximately 20 to 30 seconds, while the complete LASIK procedure may take approximately 15 minutes.
A very precise focused laser beam is guided through to the cornea in a computerized treatment that is unique to each patient. The laser beam moves across and through the cornea, creating a layer of very tiny bubbles under its path. These bubbles quickly disappear, and the tissue above the bubbles becomes the corneal flap that can be easily lifted by your surgeon.
The VisuMax features a unique, curved contact glass to maximize patient comfort. This is possible since the curved contact interface attaches to the cornea (which has a curved shape) during the treatment causing the cornea to be only slightly flattened. This unique feature prevents unnecessarily raising intraocular pressure and eliminates ocular stress. Not only does the VisuMax provide maximum comfort, this superior technology also allows you to see throughout the entire procedure! This ability is unique to VisuMax, in that microkeratomes and other femtosecond lasers cause your vision to “black out” during flap creation; patients have also reported feeling uncomfortable pressure during flap creation. However, with the VisuMax technology patients often describe the surgical flap creation to feel similar to the insertion of a soft contact lens.
Due to the Zeiss high performance optics, the laser beam is guided precisely to the desired depth, resulting in accurate flap thickness. In addition, the laser beam is directed in an extremely focused manner, which allows the surgeon to apply only minimum laser energy to the eye during the treatment. As a result, the tissue outside the defined area of the cut remains untouched.
Since the VisuMax is able to create very thin corneal flaps, some patients who were previously not a candidate for LASIK due to thin corneas, are now benefiting from this procedure, thanks to the VisuMax. Your surgeon will make the final determination.
Benefits of Blade-Free
The Femtosecond VisuMax laser provides more stability and greater flap precision when compared to other methods. The greatest complication encountered by LASIK patients post-operatively is problems with the corneal flap. The blade-free method is so precise, that it significantly reduces a patient’s risk post-operatively.
Benefits of Blade-Free VisuMax include:
⦁ Decreased risk of flap complications.
⦁ Decreased incidence of postoperative⦁ dry eye
⦁ Unlike other alternatives to LASIK, it preserves many of the benefits of LASIK including a short and largely pain-free recovery.
⦁ Increased accuracy in post-operative visual acuity
⦁ Allows consideration for candidacy in those who might have previously been poor candidates.
⦁ Reduced pressure on the eye during the procedure
⦁ Reduced incidence of patients needing a second operation to correct their vision.
⦁ Corneal flaps that are created using the blade-free method are less likely to become dislodged later
Potential Complications
What is a person's risk of having complications when choosing blade-free LASIK surgery?
As with all surgical procedures, VisuMax does present some risks, many of which are listed below. You should also understand that there may be other risks not known to the doctor which may become known later. Despite the best of care, complications and side effects may occur. A list of potential risks and complications are following:
⦁ The Femtosecond VisuMax laser could malfunction, requiring the procedure to be stopped before completion. Depending on the type of malfunction, this may or may not be accompanied by visual loss.
⦁ Irregular healing of the flap could result in a distorted cornea. This would mean that glasses or contact lenses may not correct your vision to the level possible before undergoing surgery.
⦁ Mild or severe infection is possible. Mild infection can usually be treated with antibiotics, could lead to permanent scarring and loss of vision that may require corrective laser surgery.
⦁ Other rare complications threatening vision include, but are not limited to: corneal swelling, corneal thinning (ectasia), floaters, retinal detachment, hemorrhage, and light sensitivity (photophobia).
ZEISS camera lenses were recognized as the world’s highest quality after their introduction in the 1800s. In the late 1980s, ZEISS optical lenses became the technology of choice for the developers of vision correction lasers.
Carl Zeiss Meditec has been a refractive surgery pioneer for more than 20 years.
Combining its finest optics with the most advanced excimer laser technology available, Carl Zeiss Meditec brings you laser vision correction with a fourth-generation laser platform, the MEL 80."MEL" stands for "Meditec Excimer Laser."
The MEL 80 is a fourth generation Carl Zeiss excimer laser platform, taking vision correction to a new level. By reshaping the human cornea to its most natural shape during treatment, your vision can now be similar to the quality of lenses on which Carl Zeiss has built its reputation. The goal is to deliver high resolution vision with a custom treatment unique to your prescription. Carl Zeiss engineers created this advanced vision correction technique using the latest wavefront technology innovations. This scientific method takes into consideration not only the clarity of vision from the shape of your eye, but it also treats other irregularities within your eye that may prevent you from having a higher quality of vision. As one of the fastest excimer lasers in the world, your treatment is completed within seconds!
What differentiates Carl Zeiss Meditec?
Carl Zeiss is committed to delivering superior optics with laser precision. The MEL 80 is yet another powerful example of this commitment, delivering high performance and exceptional visual results—all day and all night.
⦁ 93% of patients were corrected at 6 months to 20/20 or better visual acuity
⦁ 41% were corrected to 20/12.5 or better 6 months after treatment
⦁ MEL 80’s aberration-optimized algorithms minimize spherical aberration that causes night vision problems
Zeiss PrecisePulse™ Technology offers precision speed and safety
Precise Pulse Technology safely and accurately controls every single laser pulse from beginning to end. Using Zeiss PrecisePulse™ Technology, every beam of the laser is precisely placed on the cornea while an active eyetracker with an ultra-rapid infrared camera tracks the eye’s position 250 times per second. The MEL 80 eyetracker doesn’t use just one landmark on the eye; it uses two, which is an important feature for exact registration and laser alignment. If your eye ever moves out of the treatment range, the laser treatment pauses until the eye is realigned.
Patient Satisfaction, Comfort, and Confidence
The MEL 80 Excimer Laser System offers high performance patient comfort. It safely and significantly reduces treatment time, providing benefits for both surgeon and patient:
⦁ Reduced stromal bed exposure minimizes dehydration and accelerates regeneration
⦁ A thermally-optimized laser firing pattern protects the stroma despite high ablation speed
⦁ The ability to create a precise, aspheric corneal curvature
⦁ Patients need to concentrate on the fixation light for only a few seconds
Better for the Eye
With the tiniest spot size and its Gaussian beam profile the MEL 80 produces matchless quality in corneal ablation - exact, even and protective of the surrounding tissue. Even in complex ablation procedures, the large overlap of the laser spot zones yields very smooth surfaces.
Two specially optimized ablation profiles help you produce excellent results:
⦁ ASA (Aberration Smart Ablation) – tried and tested strongly aspherical profiles, optimized for "mesopic vision"
⦁ TSA (Tissue Saving Algorithm) – the conservative tissue-saving alternative with lower asphericity for re-treatment and thin corneas
Safe Use
The MEL 80 helps you significantly reduce the duration of treatment. This has the following benefits:
⦁ The stromal bed is only open for a short period; this prevents dehydration and speeds up the regeneration process.
⦁ The thermally-optimized distribution of the laser firing pattern protects the stroma - despite the high ablation speed.
⦁ Patients' stress is relieved; they only need to concentrate for a few seconds on the fixation light.
⦁ The exceptionally fast ablation time reduces procedure time for greater patient comfort.
⦁ Very small 0.7 mm spot permits the finest correction without losing the benefits of a small ablation.
⦁ An active eyetracker with excellent feedback times and an IR camera catching both pupil and limbus provides exact positioning during the laser treatment.
⦁ Two specially optimized ablation profiles to choose from
Clinical Study
The Carl Zeiss Meditec MEL 80 Excimer Laser System is indicated for use in primary Laser Assisted In Situ Keratomileusis (LASIK) for:
* The reduction or elimination of myopia of less than or equal to -7.0 D with or
without refractive astigmatism of less than or equal to -3.0 D;
* In subjects with documentation of stable manifest refraction over the prior year;
* In subjects who are 21 years of age or older.
Summary Of Clinical Studies:
A total of 360 eyes were enrolled in this study. Effectiveness results are provided for 354 eyes with at least six months of follow-up data. Safety data are provided for all 360 eyes enrolled in the study.
Study Objective
The objectives of this study was to evaluate the safety and effectiveness of the Meditec MEL 80 Excimer Laser System for the reduction or elimination of myopia of less than or equal to -10.00 D, and astigmatism less than or equal to -3.50 D at the spectacle plane, when used as part of the LASIK surgical procedure.
Response: At 3 Months: At 6 Months:
No Improvement 0.6% 0.6%
Slight Improvement 1.1% 0%
Moderate Improvement 1.1% 1.7%
Marked Improvement 14.4% 16.3%
Extreme Improvement 82.8% 81.5%
No 1.1% 2.2%
Yes 94.4% 94.4%
Unsure 4.4% 3.4%
Very Satisfied 90.6% 88.8%
Moderately Satisfied 7.8% 8.4%
Neutral 0.6% 1.7%
Dissatisfied 1.1% 0.6%
Very Dissatisfied 0.0% 0.6%
At three months, the overall quality of vision was rated highly, with 99.4% of patients indicating that there was an improvement, while only 0.6% indicated that there was no improvement; 94.4% would elect to have the surgery again; 98.3% reported being satisfied, while 0.6% were neutral and 1.1% were dissatisfied.
Conclusions Drawn From The Clinical Study:
The data in this application provides reasonable assurance that the device is safe and effective when used in accordance with the directions for use. The FDA issued its approval of the Meditec MEL 80 Excimer Laser System on August 15, 2006
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