LASIK
The LASIK procedure
In 1998 the FDA first approved a laser system for LASIK laser vision correction. LASIK stands for laser in situ keratomileusis and has been performed around the world since the mid 1990s. Millions of people worldwide have had this procedure successfully performed to help reduce their need for glasses or contact lenses. This surgery is used to correct nearsightedness, farsightedness, and astigmatism. The idea behind surgical vision correction is to bring the focus point of the images as close to the retina as possible, so that one’s vision is sharp.
Before making a decision though, you should make sure that you gather a good understanding of the risks and benefits associated with LASIK or other laser vision procedures, and most importantly locate a physician with which you feel comfortable. Despite all the technological advancements in refractive surgery, the physician is still the most important factor for a successful and satisfying outcome. You can never ask too many questions, after all your vision is one of the most valuable possessions that you have.
Prior to a LASIK treatment, Dr. Alexander will perform a series of extensive tests in order to determine if you are a suitable candidate for LASIK. Aside from your refraction, your physician has to ensure that you do not suffer from any ocular diseases. A comprehensive eye examination will be performed. Also, in order to perform a LASIK treatment, the thickness of your cornea is measured. Advanced diagnostic tools also enable Dr. Alexander to obtain a detailed surface map of your cornea, called corneal topography. Though the pre-operative examinations can be time consuming, they are in your best interest and ensure a safe and successful treatment.
The safest and most accurate approach to performing LASIK surgery involves a Blade–Free approach. I use the Intralase laser to create the corneal flap, and the Allegretto Wavefront-optimized excimer laser to perform the ablation, correcting the refractive error of the patient. This preferential technique of a Blade–Free LASIK, commonly called IntraLASIK, allows for reduced complications, reduced discomfort, reduced irregularities of the cornea, and provides for the best possible vision.
The LASIK Procedure
Instead of removing the uppermost corneal tissue layer, LASIK creates a flap in the cornea that is folded to the side during the laser treatment. When the treatment is finished, the flap is repositioned to its original position where it completely adheres.
Step 1
The patient is given a mild sedative prior to the procedure. Numbing eye drops are applied to the eye. Your eyelids will be cleaned and your eyelashes will be affixed with a drape in order to prevent them from disturbing the treatment and help prevent infection. The physician then inserts a holder under your eyelids to ensure your eye remains open during the procedure.
Step 2
At this time, a flap is created in your cornea. A suction ring is placed on the eye, and your vision will go black for a few seconds. This is normally done with a mechanical device called a microkeratome or the more advanced Intralase. The flap is in average only 150-180 microns thick which is the thickness of a fingernail. The physician then carefully folds the flap to the side in order to expose the corneal tissue underneath called the stroma.
Step 3
Next, the physician will ask you to fixate on a light. Then the laserlight is applied and reshapes your corneal surface. With the ALLEGRETTO WAVE, the laser application takes only about 10 seconds for a -3 diopter treatment. While the laser is running, you hear buzzing sounds and you may realize a smell similar
to burning hair.
Step 4
When the laser application is complete, the physician replaces the flap in its original position, where it completely adheres. This eliminates the pain and no sutures are required. The procedure is then repeated on the second eye.
Step 5
Following the procedure, the patient is then taken into an exam room to rest and examine the flap at the slit lamp microscope. Clear shields are taped over the eyes for protection.
Step 6
The patient will be driven home and rest for 4 hours with their eyes closed to help healing and adherence of the flap. Drops will be used frequently the first several days to assist in healing. A follow-up exam is scheduled for the next day with Dr. Alexander. Routine activities can begin the next day, except for underwater activities. Patients needing to shower should close their eyes.
Risks and Benefits
LASIK is a surgical procedure. Like any surgical procedure there are risks associated with the treatment. The most important factor is that you find a physician who you can trust. Dr. Alexander, an experienced and skilled physician, is the best insurance for you to experience a safe and successful treatment.
Please carefully read the information below and discuss any questions with
Dr. Alexander.
During the consultation, make sure you disclose ALL medications you are taking, any injuries that ever occurred to your eye, and provide a detailed medical history. Only then can your physician make a safe decision about your ability to have LASIK.
In general, you are not a good LASIK candidate if you have one or more of the following conditions:
- Your age is under 20. In this case your growth phase has not been fully completed. This means that your eyes can still change. In that case, LASIK is not a good option.
- You are pregnant or nursing. Pregnancy causes changes to your hormone system. This can also cause your vision to change. It is therefore better to wait until your child is born and you have finished nursing.
- Glaucoma or high blood pressure
- Keratoconus (a corneal thinning irregularity)
- Chronic inflammation of the eye (uveitis, blepharitis or iritis)
- Herpes simplex that has infected your eye
- Previous severe injuries on the eye
- Corneal scars or infections
- Severely dry eyes
- Amblyopia (lazy eye)
- Autoimmune diseases such as Lupus and Rheumatoid Arthritis
- You are currently taking Accutane, Cordarone, Imitrex Medications
- Other diseases of the eye such as are related macular degeneration, diabetic retinopathy, or cataract
If any of the indications listed above apply to you, make sure to consult Dr. Alexander prior to considering LASIK.
LASIK is also not recommended for patients with:
- Very large pupils
- Thin corneas
- Severely dry eyes
- Unstable refractive errors
- Patients who cannot tolerate anything less that perfect vision
- Patients who cannot tolerate any final result less than 20/20
- Patients who want perfect night vision
- Patients who cannot take prescribed drops on a schedule or cannot return for follow-up visits
If any of these apply, the right technology or surgical technique may still be able to provide you with a satisfying result. However, make sure you discuss the risks in detail with Dr. Alexander.
The Allegretto Wave Excimer Laser
The ALLEGRETTO WAVE offers a customized treatment that incorporates wavefront principles to patients with nearsightedness and even farsightedness. Every procedure is tailored to the patients’ corneal curvature and refraction with the intention to preserve the natural aspheric cornea shape and to maintain or improve quality of vision and visual acuity.
Speed
At this time, the ALLEGRETTO WAVE is today the fastest laser available to patients in the United States. In one second the system applies 200 fine laser pulses to the cornea. In fact, one diopter only takes 4 seconds to correct (at a 6.5mm true optical zone). That means that the average patient treatment with about less than 3 diopters takes only ten seconds... the time it takes you to pour yourself a cup of coffee.
Eyetracking
Such a high-speed laser must also have an ultra-fast eye tracking system to follow eye movements during the procedure. The ALLEGRETTO WAVE captures the current position of the eye 200 times per second. It then only takes the laser a fraction of a second to reposition the laser, putting it exactly into the desired location on the eye. Should the eye ever move too fast, or out of range, the laser will automatically stop and wait until the eye is back in position. So you can simply relax, knowing that your eye is being followed at all times.
PerfectPulse Technology means that every laser pulse is completely controlled as it is applied to the eye using intelligent pulse management.
This is critical as the ALLEGRETTO WAVE operates at high speed with 200 laser pulses per second. Every laser pulse is thinner than your fingernail in order to precisely sculpt the corneal surface.
Therefore, PerfectPulse Technology uses advanced high speed eyetracking to follow the eye’s fastest movements and ensures accurate placement of every laser pulse. During the treatment, the energy stability of every pulse is controlled with a smart energy control program. This program automatically balances the energy levels during the treatment to ensure that every laser pulse creates the same result.
More about PerfectPulse Technology
PerfectPulse Technology comprises many different technological components, all aimed to control the laser pulse.
Smart Energy Control measures the energy of each pulse three times while the pulse travels through the laser system. If at any of the three checkpoints the laser pulse’s energy does not meet the desired energy, the system will automatically adjust itself.
Energy is heat, and if two hundred pulses of energy are applied on the eye per second, this could potentially cause heating, which is not desirable. PerfectPulse Technology makes sure that only every fifth laser pulse overlaps the first, and therefore reduces the chances of any kind of heating effects.
PerfectPulse means that the ALLEGRETTO WAVE precisely sculpts the cornea in order to create a even ablation. With a pulse diameter of less than 1mm, and a so-called Gaussian beam profile, PerfectPulse Technology creates very fine, smooth pulses.
The eye can move at extreme velocities. Therefore it is critical to follow the eye’s movements and place the pulses into the desired location. Active-track automatic eyetracking technology ensures that this is the case. Our eyetracking system checks the position of the eye 200 times per second – as many times as laser pulses reach the eye. Once the position of the eye is determined, the laser system automatically adjusts all internal mirrors to place the next pulse into the right location. Immediately before that pulse is launched, the system reconfirms that the eye has not moved. Only then will the system release a laser pulse. The total reaction time from the detection of the eye position to the release of the next pulse is called response time. The ALLEGRETTO WAVE’s response time is only 4-6ms depending on the moving speed of the eye.
You can rely on PerfectPulse Technology to control every laser pulse from start to finish. This gives you the benefit and comfort of an ultra fast treatment and less time to worry.
Wavefront-Optimized
The ALLEGRETTO WAVE was designed with the understanding that the human cornea is not a simple optic. Based on extensive empirical research, WaveLight developed a proprietary treatment that is adjusted to the patient’s individual corneal curvature.
Imagine a glass ball.
If you took a flashlight and aimed it directly at the top of the ball, the light would form a circular shape on the surface of the ball. If you now aimed the flashlight towards the side of the ball, the light would form an elliptical shape, and not seem as bright anymore. This is because the same amount of light is suddenly distributed over a larger area. Some of the light is reflected away due to the angled surface of the glass ball.
Understanding these effects, the ALLEGRETTO WAVE applies additional laser pulses into the periphery to compensate for reflection in order to maintain the natural curved shape of the cornea. In addition, wavefront principles are applied in order to address the induction of spherical aberrations. As a result, the ALLEGRETTO WAVE creates very smooth and functional optical zones. Large, true optical zones are important in laser vision correction, especially for patients with large pupils.
During the day, the pupil is very small because of the bright daylight, but at night or under dim light conditions, the pupil opens up. A large, functional optical zone will support good vision, even under dim light conditions.
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Large Optical Zone, small pupil, Daylight Conditions (Simulation) |
Large Optical Zone, large pupil, Night Conditions (Simulation) |
In the US clinical trials more than 1000 eyes were treated successfully with PerfectPulse technology and patients reported improved quality of vision especially in regards to night driving glare.
LASIK - Frequently Asked Questions
What are myopia, hyperopia and astigmatism?
People with myopia, or nearsightedness, have more difficulty seeing distant objects, and usually see near objects clearly. People with hyperopia, or farsightedness, have more difficulty seeing near objects, and see more clearly at a distance. Astigmatism is a distortion of the image on the retina caused by irregularities in the cornea or lens curvature of the eye. Combinations of myopia and astigmatism or hyperopia and astigmatism are common.
What is LASIK?
LASIK, short for Laser Assisted In Situ Keratomileusis, is a surgical procedure that uses a cool (non-thermal) beam of light to gently reshape the cornea — the surface of the eye — to improve vision. The laser removes microscopic bits of tissue to flatten the cornea (for nearsightedness), to steepen the cornea (for farsightedness), and/or smooth out corneal irregularities (for astigmatism). In most cases, the thickness of the layer of corneal tissue removed by the laser is less than the thickness of a human hair. The goal of any laser vision correction procedure is to reshape the cornea so it does a better job of focusing images onto the retina.
How is LASIK different from previous refractive eye surgery techniques?
Current FDA approved laser vision correction methods such as LASIK, have a higher predictability of the final result with a lower incidence of complications. Additionally, older non-laser techniques typically involved manually performed incisions rather than automated lasers for correction.
Is LASIK right for everyone?
Only an eye care professional can determine whether or not an individual is eligible for LASIK treatment. In general, a good LASIK candidate is at least 20 years old, has healthy corneas, and has maintained a stable eye prescription for the last 12 months. Because hormonal levels can affect the shape of the eye, women who are pregnant or nursing should not undergo LASIK treatment. The procedure should also not be performed on patients who:
- Have glaucoma, cataracts or dry eyes
- Have collagen vascular, autoimmune or immunodeficiency diseases
- Show signs of keratoconus (an eye disorder in which there is thinning of the cornea that results in blurred or distorted images)
- Take medications with ocular side effects (such as Accutane® or Cordarone®).
Is LASIK safe?
The FDA recognizes LASIK as proven, safe and effective. According to guidelines recently released by the Eye Surgery Education Council (ESEC), fewer than 1% of patients who have received LASIK to date have experienced serious, vision-threatening problems. Most LASIK complications can be treated and usually resolve within several months of surgery. There are no known cases of blindness resulting from LASIK.
What are the risks associated with LASIK?
Although no one knows the exact number of complications, studies suggest that the incidence of minor difficulties such as dry eyes and nighttime glare, is around 3% to 5% from combined LASIK and PRK procedures. These minor complications include:
Halos - Some patients will notice glare, halos, or starburst around objects in low-light conditions. For the vast majority, these symptoms are temporary. However, others will continue to experience them for several months or longer. During pre-operative evaluation, the refractive surgeon can determine whether or not a person is at high risk for seeing long-term halos.
Dry eyes – Typically, there is increased dryness of the eyes for several months following LASIK, though some patients may experience dryness for a longer period of time. It is important to use lubricating drops frequently. If the eyes remain dry for prolonged period, there are other drops or techniques that can help. Pre-operative evaluation will help determine whether or not a person is a likely candidate for experiencing dry eyes.
Infection - This is an extremely rare occurrence, with a 1 in 2000-3000 chance (similar to any eye surgery). Fortunately, as the LASIK technique has developed over the years, and proven to be of great benefit to millions of patients nationwide, firmly established protocols now exist which minimize the risk of infection.
What happens before LASIK surgery?
Before a surgeon will perform LASIK, preoperative tests are performed to screen for glaucoma, cataracts, and other disqualifying conditions. The surgeon may also use an instrument called a corneal topographer to photograph and electronically map the eye in order to gather more information about the individual’s eyes prior to treatment.
Because contact lenses change the shape of the cornea, LASIK candidates are required to switch to eyeglasses before their baseline evaluation is taken, and stay out of contact lenses for 2-4 weeks before LASIK surgery. Failure to do so can prevent the cornea from assumimg its natural shape before surgery. This can result in inaccurate presurgical measurements and thus poor vision after surgery.
What happens during the LASIK procedure?
Once the surgeon has conducted all pre-operative examinations, the eye is anesthetized with numbing eyedrops, the area around the eye is cleaned, and an instrument called a lid speculum is used to hold the eyelids open. The surgeon will then use a specialized instrument, called a microkeratome, to cut a thin, circular flap - the outermost 20 percent of the thickness of the cornea - to expose the portion beneath. This part of the procedure is called keratectomy. This can also be performed blade – free with the Intralase Laser.
While the inner cornea (the stroma) is exposed, the surgeon will ask the patient to fixate on a specific light source above the patient. This is to ensure that the laser beam is aligned precisely with the center of the patient’s eye. Once the eye is in the correct position, the laser treatment is performed. The computer-controlled excimer laser removes the tissue under the flap and reshapes the cornea of the eye. In less than 60 seconds, ultraviolet light and high-energy pulses from the excimer laser reshape the internal cornea with accuracy up to 0.25 microns, or 1/4000 of a millimeter.
After the pulses of laser energy vaporize the corneal tissue, the flap is put back into its original position. The surgeon will observe the eye for three to five minutes to ensure bonding. Because the cornea bonds quickly, healing is rapid, and the eye does not require stitches.
Is LASIK painful?
The procedure is painless, however, most people experience 4-6 hours of mild irritation or scratchiness after their LASIK procedure. Patients are given medications, in drop form, to help with discomfort.
How long does the procedure take?
The laser treatment on the ALLEGRETTO WAVE usually takes less than thirty seconds, while the entire procedure takes around 10-15 minutes per eye.
How long must people wait to resume normal activities after a LASIK treatment?
In most cases, people can return to work within 1-3 days following LASIK surgery. Excluding the day of surgery itself, people may begin driving as soon as they see well enough. Women can start wearing makeup within two to three days of treatment, however, they are advised to wear only new cosmetics in order to decrease risk of infection.
Will a person’s vision remain stable long after the procedure?
The vision correction is permanent. However, a person’s vision may change naturally with time, and LASIK does not affect visual conditions that may develop with age. Also, LASIK does not prevent presbyopia and the eventual need for reading glasses. Depending on the cause, retreatment may be a viable solution to later vision changes, and other treatment options also exist.
IntraLase®- Frequently Asked Questions
What is the IntraLase Method™? The IntraLase Method is a 100% blade-free technique used to perform the critical first step in the LASIK procedure: creating the corneal flap. The creation of the corneal flap prepares the eye for the second step of the LASIK procedure, where an excimer laser is used on the inner cornea to correct vision. How does the IntraLase Method work? The IntraLase Method uses tiny, rapid pulses of laser light to create your corneal flap—instead of using a metal blade—during the first step of LASIK. Each pulse of light passes through the top layers of your cornea and forms a microscopic bubble at a specific depth and position within your eye that is determined by the doctor. The IntraLase® laser moves back and forth across your eye, creating a uniform layer of bubbles just beneath your corneal surface. Just prior to applying laser vision correction, the doctor creates your corneal flap by gently separating the tissue where these bubbles have formed. The corneal flap is then folded back so the doctor can perform the second step of your LASIK treatment. What is the difference between a corneal flap created with the IntraLase Method and one created with a microkeratome? The microkeratome is a hand-held instrument, which contains a steel blade that moves back and forth and creates a cut as it travels across the cornea. A microkeratome is only capable of making a single, one-dimensional cut across the cornea. As it cuts, the blade oscillates back and forth, which can leave an irregular surface after the flap is lifted. This can affect the quality of your postoperative vision. How is the IntraLase Method different from Epi-LASIK or photo-refractive keratectomy (PRK)? These procedures differ from one another in the way they prepare the surface of the cornea for the second step of LASIK. Epi-LASIK uses an epikeratome—a blunt separator—to make a superficial flap. Similarly, photo-refractive keratectomy (PRK) is performed by gently scraping the surface layer of the cornea, which may lead to corneal scarring. Both the Epi-LASIK and PRK procedures can be painful and require more postoperative medication. In addition, healing times may be longer than with procedures performed with the IntraLase Method. Are there other benefits to using the IntraLase Method? There are several benefits to using the IntraLase Method: Is the IntraLase Method painful? Prior to creating the flap, the doctor applies drops to numb the eye, and then applies a special ring and an instrument that gently flattens your cornea in preparation for the IntraLase Method. This part of the process is not painful—patients report feeling only slight pressure. More than 600,000 procedures have been performed safely and effectively using the IntraLase Method. How long does it take to create a flap using the IntraLase Method? The creation of the flap itself takes only about 15-30 seconds per eye. Including preparation time, the entire LASIK procedure takes about 10 minutes. What’s the reaction of patients who have experienced the IntraLase Method? Is the IntraLase Method right for me? If you are looking for a 100% blade-free LASIK experience that virtually eliminates almost all the most severe, sight-threatening complications, the answer is yes. But to get this procedure, you have to ask your physician for the IntraLase Method™ by name. |