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Information on LASIK refractive surgery. | How does laser eye surgery work

LASIK, or "laser-assisted in-situ keratomileusis," is the most common laser eye surgery performed to treat nearsightedness (myopia), farsightedness (hyperopia), and astigmatism.

LASIK, laser-assisted in-situ keratomileusis.
LASIK, laser-assisted in-situ keratomileusis.

Spanish ophthalmologist José Ignacio Barraquer Moner

He wanted to find a solution to the problem of blurry vision without the help of devices. Barrucker began by cutting off the cornea at the front and placing it in liquid nitrogen.

With a miniature machine he grinded the frozen cornea and gave it the shape it needed to give the patient a clear view. 

Then he defrosted the corneal disc and sewed it back on, Barraquer called this operation Keratomileusis, which is the Greek word for corneal reshaping, and although it is scary to imagine, his treatment method has yielded good results.

Like other types of refractive surgery, the LASIK procedure shapes the cornea to allow light entering the eye to be properly focused on the retina, resulting in clearer vision.

In most cases, laser eye surgery is painless and can be completed in about 15 minutes for both eyes. 

The results, including improved vision without the use of glasses or contact lenses, can usually be seen in as little as 24 hours.

If you are not a good candidate for LASIK surgery, other vision correction surgeries are available, such as PRK laser eye surgery and LASEK, as well as phakic intraocular lens surgery. 

Your eye doctor will determine if any of these procedures is appropriate for your particular condition and, if so, which technique would be best.

How is LASIK surgery performed?

First, the eye surgeon uses either a mechanical surgical instrument called a microkeratome or a femtosecond laser to create a thin, circular layer (flap) on the cornea.

The surgeon then folds back that jointed layer to access the underlying cornea (called the stroma) and removes some of the corneal tissue using the excimer laser.

This highly specialized laser uses a cold ultraviolet light beam and removes (ablation) microscopic amounts of corneal tissue to shape the cornea so that it focuses light on the retina more precisely to improve vision.

In nearsighted people, the goal is to flatten the cornea. In farsighted people, a steep cornea is more desirable.

The excimer laser can also correct astigmatism by smoothing the irregular cornea and leaving it more normally shaped. It is a misconception that LASIK surgery cannot treat astigmatism.

Once the laser shapes the cornea, the layer that was created is put back in place by covering the area where the corneal tissue was removed. The cornea is then allowed to heal naturally.

Laser eye surgery requires only a few drops of local anesthetic. No bandages or stitches are required.

Before LASIK Surgery

The eye doctor will perform a thorough eye exam to make sure your eyes are healthy enough for the procedure. The doctor will evaluate: the shape and thickness of the cornea, the size of the pupil, refractive errors (nearsightedness, farsightedness, and astigmatism), as well as other eye conditions.

The eyes will also be tested for moisture, and preventive treatment may be recommended to reduce the risk of developing dry eye syndrome after LASIK surgery.

Typically, an automated instrument called a corneal topographer is used to measure the curvature of the front surface of the eye and create a "map" of the cornea.

With the help of the wavefront technology associated with custom LASIK surgery, you are also likely to have wavefront analysis, which sends light waves through the eye to more accurately map aberrations that affect vision.

Your eye doctor will also evaluate your general health and medical history, as well as any medications you are taking, to determine if you are an appropriate candidate for LASIK surgery.

In addition, he or she will recommend that you stop wearing contact lenses for a period of time (usually about two weeks) before your eye exam and prior to LASIK surgery, as contact lenses can alter the natural shape of the cornea.

What can you expect during LASIK surgery?

Before the surgery begins, anesthetic eye drops are applied to the eyes to prevent any discomfort during the procedure. The doctor may also give you some medicine to help you relax.

The eye is positioned under the laser and an instrument called a palpebral speculum is used to hold the eyelids open.

The surgeon uses an ink marker to mark the cornea before creating the layer. Next, he will place a suction ring over the front of your eye to prevent eye movement or loss of contact because this could affect the quality of the layer to be created.

Once the corneal layer has been created, the surgeon uses a computer to adjust the excimer laser according to your specific prescription.

You will be asked to look at a specific light for a short period of time while the surgeon looks at the eye through the microscope when the laser is emitting the pulses of light to the cornea.

The pulses of laser light shape the cornea painlessly, although you may feel some pressure in your eye. You will also constantly hear a clicking sound while the laser is working.

LASIK surgery is performed on each eye separately, and each procedure takes only about five minutes.

Immediately After LASIK Surgery

After the completion of LASIK surgery, the surgeon will let you rest for a while. You may feel a temporary burning or stinging sensation immediately after the procedure. 

After a brief post-operative examination, you will be discharged and should have someone drive you home. You cannot drive a vehicle after LASIK surgery until your eye doctor sees you in consultation the next day and confirms that your uncorrected vision meets the legal standard for driving.

You will experience some blurring and haziness immediately after surgery; however, clarity should improve the next morning.

Vision should stabilize and continue to improve within a few days, although in exceptional cases it may take several weeks or even longer. For most people, vision improves immediately.

You can go to work the next day, but many doctors advise a couple of days off.

In addition, it is generally recommended that you refrain from any strenuous exercise for at least a week as this can cause trauma to the eye and impair healing.

You will usually return to see your eye doctor or LASIK surgeon the day after surgery.

At this initial checkup, the doctor will test your vision to make sure you have the legal minimum to drive a vehicle without glasses or contact lenses. 

In most states in the U.S., uncorrected visual acuity is required to be 20/40 or higher.

As with any surgery, you should always follow your doctor's instructions and take any medications that have been prescribed for you. 

Also, avoid rubbing your eye because there is a small chance that doing so may cause the coating to come off before it has healed and adhered more securely to the underlying cornea.

Long-term results

Laser eye surgery offers numerous advantages and can greatly improve the quality of life. Most people achieve 20/20 vision or better after surgery, but the results of LASIK surgery vary. Some people achieve only 20/40 vision or less.

You may still need to wear glasses or contact lenses after laser vision correction, although your prescription level will be much lower than before.

If you have a mild residual refractive error after LASIK surgery and you want clearer vision for certain activities, such as driving a car at night, in many cases, prescription glasses with an anti-reflective coating can benefit you. 

Also, if you are sensitive to sunlight after LASIK surgery, ask your eye care professional about the possibility of wearing glasses with photochromic lenses.

Although the procedure has an excellent safety profile, some LASIK surgery complications can occur, including infection and glare (flashes and halos that are more noticeable when you are looking at lights at night, such as when driving a car).

A small percentage of people will need LASIK enhancement surgery, or a "touch-up" procedure a few months after the initial LASIK surgery, to achieve acceptable visual acuity.

It may also be necessary to wear reading glasses once you reach age forty due to normal age-related loss of near vision, a condition called presbyopia.

Although LASIK surgery has a high success rate, it is important that you discuss all facets of the procedure with your surgeon before consenting to have the surgery.


Latest LASIK Surgery Results Better Than Ever, Researchers Conclude...

The results of modern LASIK surgery, as measured by visual acuity, refractive results and patient satisfaction, are better than ever before, according to a meta-analysis of recent studies on the vision correction procedure.

A team of researchers from refractive surgery centers in the United States and Germany analyzed the results of 97 LASIK surgery studies published between 2008 and 2015. The results of nearly 68,000 eyes that had undergone the procedure were evaluated.

In interpreting the data from the studies, the researchers determined that:

  1. 99.5% of the eyes had better distance visual acuity, without 20/40 correction after LASIK surgery.
  2. 98.6 % of the eyes were within +/- 1.0 diopters (D) according to the expected refractive result.
  3. 90.9 % of the eyes were within +/- 0.5 diopters (D) according to the expected refractive result.
  4. 98.8% of patients reported satisfaction with their LASIK results.

According to the study authors, the results of these recently published studies were better than those described in the safety and efficacy summaries of previous U.S. Food and Drug Administration (FDA)-approved laser refractive surgery systems. 

The results support the safety and efficacy of the procedure, as well as patient satisfaction, have been concluded.

The full report was published in the August 2016 issue of the Journal of Cataract & Refractive Surgery. - G.H.