When is LASIK not for me?

You are probably NOT a good candidate for refractive surgery if:

You are not a risk taker. Certain complications are unavoidable in a percentage of patients, and there are no long-term data available for current procedures.

It will jeopardize your career. Some jobs prohibit certain refractive procedures. Be sure to check with your employer/professional society/military service before undergoing any procedure.

Cost is an issue. Most medical insurance will not pay for refractive surgery. Although the cost is coming down, it is still significant.

You required a change in your contact lens or glasses prescription in the past year. This is called refractive instability. Patients who are:

In their early 20s or younger,
Whose hormones are fluctuating due to disease such as diabetes,
Who are pregnant or breastfeeding, or
Who are taking medications that may cause fluctuations in vision,

are more likely to have refractive instability and should discuss the possible additional risks with their doctor.

You have a disease or are on medications that may affect wound healing. Certain conditions, such as autoimmune diseases (e.g., lupus, rheumatoid arthritis), immunodeficiency states (e.g., HIV) and diabetes, and some medications (e.g., retinoic acid and steroids) may prevent proper healing after a refractive procedure.

You actively participate in contact sports. You participate in boxing, wrestling, martial arts or other activities in which blows to the face and eyes are a normal occurrence.

You are not an adult. Currently, no lasers are approved for LASIK on persons under the age of 18.

Precautions
The safety and effectiveness of refractive procedures has not been determined in patients with some diseases. Discuss with your doctor if you have a history of any of the following:

Herpes simplex or Herpes zoster (shingles) involving the eye area.
Glaucoma, glaucoma suspect, or ocular hypertension.
Eye diseases, such as uveitis/iritis (inflammations of the eye)
Eye injuries or previous eye surgeries.
Keratoconus

Other Risk Factors
Your doctor should screen you for the following conditions or indicators of risk:

Blepharitis. Inflammation of the eyelids with crusting of the eyelashes, that may increase the risk of infection or inflammation of the cornea after LASIK.

Large pupils. Make sure this evaluation is done in a dark room. Younger patients and patients on certain medications may be prone to having large pupils under dim lighting conditions. This can cause symptoms such as glare, halos, starbursts, and ghost images (double vision) after surgery. In some patients these symptoms may be debilitating. For example, a patient may no longer be able to drive a car at night or in certain weather conditions, such as fog.

Thin Corneas. The cornea is the thin clear covering of the eye that is over the iris, the colored part of the eye. Most refractive procedures change the eye’s focusing power by reshaping the cornea (for example, by removing tissue). Performing a refractive procedure on a cornea that is too thin may result in blinding complications.

Previous refractive surgery (e.g., RK, PRK, LASIK). Additional refractive surgery may not be recommended. The decision to have additional refractive surgery must be made in consultation with your doctor after careful consideration of your unique situation.

Dry Eyes. LASIK surgery tends to aggravate this condition.

Source: U.S. Food and Drug Administration

What is LASIK?

The eye and vision errors

The cornea is a part of the eye that helps focus light to create an image on the retina. It works in much the same way that the lens of a camera focuses light to create an image on film. The bending and focusing of light is also known as refraction. Usually the shape of the cornea and the eye are not perfect and the image on the retina is out-of-focus (blurred) or distorted. These imperfections in the focusing power of the eye are called refractive errors. There are three primary types of refractive errors: myopia, hyperopia and astigmatism. Persons with myopia, or nearsightedness, have more difficulty seeing distant objects as clearly as near objects. Persons with hyperopia, or farsightedness, have more difficulty seeing near objects as clearly as distant objects. Astigmatism is a distortion of the image on the retina caused by irregularities in the cornea or lens of the eye. Combinations of myopia and astigmatism or hyperopia and astigmatism are common. Glasses or contact lenses are designed to compensate for the eye's imperfections. Surgical procedures aimed at improving the focusing power of the eye are called refractive surgery. In LASIK surgery, precise and controlled removal of corneal tissue by a special laser reshapes the cornea changing its focusing power.

Other types of refractive surgery

Radial Keratotomy or RK and Photorefractive Keratectomy or PRK are other refractive surgeries used to reshape the cornea. In RK, a very sharp knife is used to cut slits in the cornea changing its shape. PRK was the first surgical procedure developed to reshape the cornea, by sculpting, using a laser. Later, LASIK was developed. The same type of laser is used for LASIK and PRK. Often the exact same laser is used for the two types of surgery. The major difference between the two surgeries is the way that the stroma, the middle layer of the cornea, is exposed before it is vaporized with the laser. In PRK, the top layer of the cornea, called the epithelium, is scraped away to expose the stromal layer underneath. In LASIK, a flap is cut in the stromal layer and the flap is folded back.

Another type of refractive surgery is thermokeratoplasty in which heat is used to reshape the cornea. The source of the heat can be a laser, but it is a different kind of laser than is used for LASIK and PRK. Other refractive devices include corneal ring segments that are inserted into the stroma and special contact lenses that temporarily reshape the cornea (orthokeratology).

What the FDA regulates

In the United States, the Food and Drug Administration (FDA) regulates the sale of medical devices such as the lasers used for LASIK. Before a medical device can be legally sold in the U.S., the person or company that wants to sell the device must seek approval from the FDA. To gain approval, they must present evidence that the device is reasonably safe and effective for a particular use, the "indication." Once the FDA has approved a medical device, a doctor may decide to use that device for other indications if the doctor feels it is in the best interest of a patient. The use of an approved device for other than its FDA-approved indication is called "off-label use." The FDA does not regulate off-label use or the practice of medicine.

The FDA does not have the authority to:

Regulate a doctor's practice. In other words, FDA does not tell doctors what to do when running their business or what they can or cannot tell their patients.
Set the amount a doctor can charge for LASIK eye surgery.
"Insist" the patient information booklet from the laser manufacturer be provided to the potential patient.
Make recommendations for individual doctors, clinics, or eye centers. FDA does not maintain nor have access to any such list of doctors performing LASIK eye surgery.
Conduct or provide a rating system on any medical device it regulates.
The first refractive laser systems approved by FDA were excimer lasers for use in PRK to treat myopia and later to treat astigmatism. However, doctors began using these lasers for LASIK (not just PRK), and to treat other refractive errors (not just myopia). Over the last several years, LASIK has become the main surgery doctors use to treat myopia in the United States. More recently, some laser manufacturers have gained FDA approval for laser systems for LASIK to treat myopia, hyperopia and astigmatism and for PRK to treat hyperopia and astigmatism.

See the section on FDA-approved lasers for more details on which lasers have received FDA approval and the specific indications and treatment ranges for which they were approved.

Source: U.S. Food and Drug Administration

LASIK FAQ

What is LASIK's history?

What is LASIK, and how is it done?

What does the name of the LASIK procedure mean?

How long has LASIK been performed?

Is LASIK for me?

Who can LASIK benefit?

Who can't have LASIK?

If I'm not eligible for LASIK, are there other options available to me?

I am happy with my contact lenses. Should I pursue having LASIK?

How much does it cost?

How much does LASIK cost?

Does insurance cover this surgery?

What can I expect my vision to be like after LASIK?

What results can I expect from LASIK?

Will my vision be as crisp after LASIK?

How long will it take before I can see well, and how long will it take before I have my best vision?

Will I need to wear glasses or bifocals once my eyes have healed?

After LASIK, how will my vision be at night or in low light?

Will my eyes be dry after LASIK?

Are the results achieved from LASIK permanent?

If I have LASIK and my vision changes later in life, can it be redone?

Does the procedure hurt?

Does the LASIK procedure hurt?

What kind of anesthetic is used for LASIK?

How safe is the LASIK procedure?

Will having LASIK inconvenience me?

Can I have both eyes done with LASIK at the same time?

If I have one eye done at a time, what will my vision be like in between the first and second surgeries?

How long will I be out of work after having LASIK?

Can I play sports after LASIK surgery?

Can I drive immediately after having LASIK?

Will my eyes look different after LASIK?

Is LASIK still considered investigational?

Is LASIK investigational?

Why do I sometimes hear LASIK referred to as a practice of medicine procedure?

Is LASIK an off-label use of the excimer laser?

If LASIK is an off-label use on some lasers, why do ophthalmologists opt to do this procedure?

Safety and efficacy

The reported figures for safety and efficacy are open to interpretation. In 2003, the Medical Defence Union (MDU), the largest insurer for doctors in the United Kingdom, reported a 166% increase in claims involving laser eye surgery; however, the MDU averred that these claims resulted primarily from patients' “unrealistic expectations” of LASIK rather than “faulty surgery”. A 2003 study reported in the medical journal Ophthalmology found that nearly 18% of treated patients and 12% of treated eyes needed retreatment. The authors concluded that “higher initial corrections, astigmatism, and older age are risk factors for LASIK retreatment.”

In 2004, the British National Health Service's National Institute for Health and Clinical Excellence (NICE) considered a systematic review of four randomized controlled trials before issuing guidance for the use of LASIK within the NHS. Regarding the procedure's efficacy, NICE reported, "Current evidence on LASIK for the treatment of refractive errors suggests that it is effective in selected patients with mild or moderate short-sightedness" but that "evidence is weaker for its effectiveness in severe short-sightedness and long-sightedness." Regarding the procedure's safety, NICE reported that "there are concerns about the procedure's safety in the long term and current evidence does not appear adequate to support its use within the NHS without special arrangements for consent and for audit or research." Leading refractive surgeons in the United Kingdom and United States, including at least one author of a study cited in the report, believe NICE relied on information that is severely dated and weakly researched.

Industry concerns

There are many concerns and movements to change the way the LASIK industry operates. Primarily these are based on the distribution of information by surgeons to potential patients. It is often argued that patients are not given sufficent information regarding the possible complications, their side effects, and final outcomes.[Please name specific person or group] A survey in the United Kingdom indicated that most LASIK patients expected their vision to become at least 20/20 after surgery and few knew it could potentially be worse.

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Satisfaction

Various surveys have been performed to determine patient satisfaction with LASIK. These surveys have found most patients to be satisfied, with anywhere from 92-98% of respondents describing themselves as satisfied. Those who are unsatisfied tend to be those who have had some of the above-described complications.

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Complications

The incidence of refractive surgery patients having unresolved complications six months after surgery has been estimated from 3% to 6%. The following are some of the more frequently reported complications of LASIK:

Dry eyes

Overcorrection or undercorrection

Visual acuity fluctuation

Halos or starbursts around light sources at night

Light sensitivity

Ghosts or double vision

Wrinkles in flap (striae)

Decentered ablation

Debris or growth under flap

Thin or buttonhole flap

Induced astigmatism

Epithelium erosion

Posterior vitreous detachment

Macular hole

Complications due to LASIK have been classified as those that occur due to preoperative, intraoperative, early postoperative, or late postoperative sources

Preoperative sources of complications

Intraoperative complications

The incidence of flap complications has been estimated to be 0.244%. Flap complications (such as displaced flaps or folds in the flaps that necessitate repositioning, diffuse lamellar keratitis, and epithelial ingrowth) are common in lamellar corneal surgeries but rarely lead to permanent visual acuity loss; the incidence of these microkeratome-related complications decreases with increased physician experience. This risk is further reduced by the use of IntraLasik and other non-microkeratome related approaches.

A slipped flap (a corneal flap that detaches from the rest of the cornea) is one of the most common complications. The chances of this are greatest immediately after surgery, so patients typically are advised to go home and sleep, to let the flap heal.

Flap interface particles are another finding whose clinical significance is undetermined. A Finnish study found that particles of various sizes and reflectivity were clinically visible in 38.7% of eyes examined via slit lamp biomicroscopy, but apparent in 100% of eyes using confocal microscopy.

Early postoperative complications

The incidence of diffuse lamellar keratitis (DLK), also known as the Sands of Sahara syndrome, has been estimated at 2.3%. When diagnosed and appropriately treated, DLK resolves with no lasting vision limitation.

The incidence of infection responsive to treatment has been estimated at 0.4%. Infection under the corneal flap is possible. It is also possible that a patient has the genetic condition keratoconus that causes the cornea to thin after surgery. Although this condition is screened in the preoperative exam, it is possible in rare cases (about 1 in 5,000) for the condition to remain dormant until later in life (the mid-40s). If this occurs, the patient may need rigid gas permeable contact lenses, Intrastromal Corneal Ring Segments (Intacs), Corneal Collagen Crosslinking with Riboflavin or a corneal transplant

The incidence of persistent dry eye has been estimated to be as high as 28% in Asian eyes and 5% in Caucasian eyes. Nerve fibers in the cornea are important for stimulating tear production. A year after LASIK, subbasal nerve fiber bundles remain reduced by more than half. Some patients experience reactive tearing, in part to compensate for chronic decreased basal wetting tear production.

The incidence of subconjunctival hemorrhage has been estimated at 10.5%.

Late postoperative complications

The incidence of epithelial ingrowth has been estimated at 0.1%.

Glare is another commonly reported complication of those who have had LASIK.

Halos or starbursts around bright lights at night are caused by the irregularity between the lasered part and the untouched part. It is not practical to perform the surgery so that it covers the width of the pupil at full dilation at night, and the pupil may expand so that light passes through the edge of the flap into the pupil. In daytime, the pupil is smaller than the edge. Modern equipment is better suited to treat those with large pupils, and responsible physicians will check for them during examination.

Other

Although there have been a number of improvements in LASIK technology, a large body of conclusive evidence on the chances of long-term complications is not yet in place. Also, there is a small chance of complications, such as slipped flap, corneal infection, haziness, halo, or glare. The procedure is irreversible.

The incidence of macular hole has been estimated at 0.2% to 0.3%.

The incidence of retinal detachment has been estimated at 0.36%.

The incidence of choroidal neovascularization has been estimated at 0.33%.

The incidence of uveitis has been estimated at 0.18%

Although the cornea usually is thinner after LASIK because of the removal of part of the stroma, refractive surgeons strive to maintain a minimum thickness in order to not structurally weaken the cornea. Decreased atmospheric pressure at higher altitudes has not been shown to be extremely dangerous to the eyes of LASIK patients. However, some mountain climbers have experienced a myopic shift at extreme altitudes. There are no published reports documenting diving-related complications after LASIK.

Laser in situ keratomileusis increases higher order wavefront aberrations of the cornea. Glasses do not correct higher order aberrations.

Microfolding has been reported as "an almost unavoidable complication of LASIK" whose "clinical significance appears negligible".

Factors affecting surgery

The cornea typically is avascular because it must be transparent to function normally. Its cells absorb oxygen from the tear film. Low oxygen-permeable contact lenses reduce the cornea's absorption of oxygen, which sometimes results in the growth of blood vessels into the cornea, a process known as corneal neovascularization. This can cause a mild increase in inflammation and healing time and some discomfort during the surgery because of augmented bleeding. Although some contact lenses, notably modern RGP and soft silicone hydrogel lenses, are made of materials with higher oxygen permeability that help reduce the risk of corneal neovascularization, patients considering LASIK are cautioned to avoid overwearing their lenses. It is usually recommended that contact lens use be discontinued several days or weeks before the LASIK procedure.

A 2004 Wake Forest University study found that LASIK results are affected by heat and humidity, both during the procedure and in the two weeks before surgery.

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Higher-order aberrations

Higher-order aberrations are visual problems not captured in a traditional eye exam which only tests for acuteness of vision. Severe aberrations can effectively cause significant vision impairment. These aberrations include starbursts, ghosting, halos, double vision, and a number of other post-operative complications listed below.

Concern has long plagued the tendency of refractive surgeries to induce higher-order aberration not correctible by traditional contacts or glasses. The advancement of LASIK technique and technologies has helped reduce the risk of clinically significant visual impairment after the surgery. One of the major discoveries was the correlation between pupil size and aberrations: Effectively, the larger the pupil size, the greater the risk of aberrations. This correlation is the result of the irregularity between the untouched part of the cornea and the reshaped part.

Daytime post-lasik vision is optimal, since the pupil is smaller than the LASIK flap. But at night, the pupil may expand such that light passes through the edge of the LASIK flap into the pupil which gives rise to many aberrations. There are other currently unknown factors in addition to pupil size that also affect higher order aberrations.

In extreme cases, where ideal technique was not followed and before key advances, some people could suffer rather debilitating symptoms including serious loss of contrast sensitivity in poor lighting situations.

Over time, most of the attention has been focused on spherical aberration. LASIK and PRK tend to induce spherical aberration, because of the tendency of the laser to undercorrect as it moves outward from the center of the treatment zone. This is really only a significant issue for large corrections. There is some thought if the lasers were simply programmed to adjust for this tendency, no significant spherical aberration would be induced. Hence, in eyes with little existing higher order aberrations, "wavefront optimized" lasik rather than wavefront guided LASIK may well be the future. Regardless, most patients with even the low to medium corrections remain highly satisfied even with conventional LASIK, however patients requiring higher corrections often complain about night vision.

Wavefront-guided LASIK

Wavefront-guided LASIK is a variation of LASIK surgery where, rather than apply a simple correction of focusing power to the cornea (as in traditional LASIK), an ophthalmologist applies a spatially varying correction, using a computer-controlled high-power UV laser guided by measurements from a wavefront sensor. The goal is to achieve a more optically perfect eye, though the final result still depends on the physician's success at predicting changes which occur during healing. In older patients though, scattering from microscopic particles plays a major role and may exceed any benefit from wavefront correction. Hence, patients expecting so-called "super vision" from such procedures may be disappointed. However, while unproven, surgeons claim patients are generally more satisfied with this technique than with previous methods, particularly regarding lowered incidence of "halos", the visual artifact caused by spherical aberration induced in the eye by earlier methods.

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Lasik Procedure

Preoperative

Patients wearing soft contact lenses typically are instructed to stop wearing them approximately 7 to 10 days before surgery. One industry body recommends that patients wearing hard contact lenses should stop wearing them for a minimum of six weeks plus another six weeks for every three years the hard contacts had been worn. Before the surgery, the surfaces of the patient's corneas are examined with a pachymeter to determine their exact shape. Using low-power lasers, it creates a topographic map of the cornea. This process also detects astigmatism and other irregularities in the shape of the cornea. Using this information, the surgeon calculates the amount and locations of corneal tissue to be removed during the operation. The patient typically is prescribed an antibiotic to start taking beforehand, to minimize the risk of infection after the procedure.

Operation

The operation is performed with the patient awake and mobile; however, the patient typically is given a mild sedative (such as Valium) and anesthetic eye drops.

Lasik is performed in two steps. The initial step is to create a flap of corneal tissue. This process is achieved with a mechanical microkeratome using a metal blade, or a femtosecond laser microkeratome (procedure known as IntraLASIK) that creates a series of tiny closely arranged bubbles within the cornea. A hinge is left at one end of this flap. The flap is folded back, revealing the stroma, the middle section of the cornea. The process of lifting and folding back the flap can be uncomfortable.

The second step of the procedure is to use an excimer laser (193 nm) to remodel the corneal stroma. The laser vaporizes tissue in a finely controlled manner without damaging adjacent stroma by releasing the molecular bonds that hold the cells together. No burning with heat or actual cutting is required to ablate the tissue. The layers of tissue removed are tens of micrometers thick.

During the second step, the patient's vision will become very blurry once the flap is lifted. He/she will be able to see only white light surrounding the orange light of the laser. This can be disorienting.

Currently manufactured excimer lasers use a computer system that tracks the patient's eye position up to 4,000 times per second, redirecting laser pulses for precise placement. After the laser has reshaped the cornea, the Lasik flap is repositioned over the treatment area by the surgeon. The flap remains in position by natural adhesion until healing is completed.

Performing the laser ablation in the deeper corneal stroma typically provides for more rapid visual recovery and less pain.

Postoperative

Patients are usually given a course of antibiotic and anti-inflammatory eye drops. These are discontinued in the weeks following surgery. Patients are also given a darkened pair of goggles to protect their eyes from bright lights and protective shields to prevent rubbing of the eyes when asleep.

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The LASIK Technology development

The LASIK technique was made possible by Jose Barraquer (Colombia), who around 1960 developed the first microkeratome, used to cut thin flaps in the cornea and alter its shape, in a procedure called keratomileusis.
In 1981, Rangaswamy Srinivasan discovered that an ultraviolet excimer laser could etch living tissue in a precise manner with no thermal damage to the surrounding area. He named the phenomenon Ablative Photodecomposition (APD). Srinivasan and his co-inventors ran tests using the excimer laser and a conventional, green laser to etch organic matter. They discovered that while the green laser produced rough incisions, damaged by charring from the heat, the excimer laser produced clean, neat incisions. In 1983, Srinivasan collaborated with an ophthalmic surgeon to develop APD to etch the cornea.

LASIK surgery was developed in 1990 by Lucio Buratto (Italy) and Ioannis Pallikaris (Greece) as a melding of two prior techniques, keratomileusis and photorefractive keratectomy. It quickly became popular because of its greater precision and lower frequency of complications in comparison with these former two techniques.

In 1991, LASIK was performed for the first time in the United States by Stephen Brint and Stephen Slade.

Today, faster lasers, larger spot areas, bladeless flap incision, and wavefront-optimized and -guided techniques have significantly improved the reliability of the procedure as compared to that of 1991. Nonetheless, the fundamental limitations of excimer lasers and undesirable destruction of the eye's nerves have spawned research into many alternatives to "plain" LASIK, including all-femtosecond correction (FLIVC), LASIK, Epi-LASIKK, wavefront-guided PRK, and modern intraocular lenses. Furthermore, the long term effects of LASIK surgery still remain unknown.

The energy of each pulse is usually in the milliwatt range. Typically, each pulse is on the order of 10-20 nanoseconds.

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LASIK

LASIK, an acronym for Laser-Assisted in Situ Keratomileusis, is a form of refractive laser eye surgery procedure performed by ophthalmologists intended for correcting myopia, hyperopia, and astigmatism. The procedure is usually a preferred alternative to photorefractive keratectomy, PRK, as it requires less time for full recovery, and the patient experiences less pain overall. Many patients choose LASIK as an alternative to wearing corrective glasses or contact lenses. While LASIK has the ability to provide acute vision, there is no benchmark to quantify the quality of the image a patient sees.

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