LASIK (Laser-Assisted In Situ Keratomileusis) is a type of eye surgery that can correct myopia, hyperopia and astigmatism. A laser or microkeratome is used to reshape the cornea. The first step is to create a thin flap on the eye. This flap is then folded and the tissue beneath it is remodeled. The flap is then repositioned.

Proper post-operative care is important to prevent complications. You can be expected to be prescribed eye drops that are both antibiotic and anti-inflammatory and it is important that you keep using them according the prescription even if your eyes feels great soon after surgery. To prevent dry eyes, moisturizing eye drops are used as well. Post-operative care will also involve resting the eyes and using dark sunglasses to protect the eyes from bright lights.

In some eye clinics, a protective contact lens is placed on the eye right after surgery and removed by the surgeon a few days later.

In 2008, The American Society of Cataract and Refractive Surgery published a patient satisfaction meta-analysis of over 3,000 peer-reviewed articles from international clinical journals. This study showed a 95.4% patient satisfaction rate among LASIK patients. This data came from the prior 10 years.

laserThe LASIK procedure

Prior to the procedure, numbing eye drops will be administered. You may also get a mild oral sedative to help you relax.

1.) During surgery, the eye is held in place by a soft corneal suction ring. This causes a temporary dimming of vision.

  1. The surgeon uses a microkeratome (with a metal blade) or a femtosecond laser to cut through the corneal epithelium and Bowman’s layer and create a flap. A hinge is left at the end of the flap.
  1. The surgeon folds back the flap to unveil the stroma, i.e. the middle section of the cornea. An excimer laser is then used to remodel the stroma. The laser vaporizes unwanted tissue without injuring the tissue that is to be left intact. The tissue that is vaporized is just tens of micrometers thick. The excimer laser employs a highly sophisticated eye tracking system that follows the eye’s position up to 4,000 times per second. This system makes it possible to place the laser pulses at the exact right spot.N.B!
  • The eye isn’t burned by hot laser rays or anything like that during a LASIK procedure.
  • A typical pulse is approximately 1 millijoule of pulse energy and only lasts for 10 – 20 nanoseconds.
  • As long as the flap is folded back, your vision on that eye will be blurry. In the blur, you will see the orange light of the laser and it will probably be surrounded by a white light. This can be somewhat disorienting.
  1. When the surgeon is finished reshaping the stroma, the flap will be put back in place again. The surgeon will make sure that there is no debris or air bubbles trapped under the flap, and that the flap still fits the eye correctly.

N.B! During LASIK surgery, the eye is held in place by a soft corneal suction ring. During the procedure, the suction can make small blood vessels in the eye burst. This isn’t dangerous, but subconjuvital hemorrhage can make the white of the eyes look red for a few weeks.

Before - After LASIK

Before – After LASIK

LASIK risks

LASIK is a medical procedure and there are always a risk of side effects and complications, or that the surgery doesn’t produce the high degree of visual correction desired.

Examples of risks listed by the U.S. Food and Drug Administration.

  • Dry eyes
  • Pain
  • Problems with vision that can not be corrected, or can not be completely corrected, with glasses, contact lenses or new surgery.
  • Halos, glare and/or double vision that impacts nighttime vision.
  • Problems with vision in low-contrast situations, such as night or fog.
  • Being under treated or over treated.

Other important information:

  • It is not always possible to obtain 20/20 vision through LASIK. Some patients still need glasses or contacts after LASIK. This is especially true for patients that had very large refractive errors before LASIK.
  • If you needed reading glasses before LASIK, you may still need them afterwards.
  • If you are farsighted, the improved vision after LASIK may diminish with age.
  • Since LASIK is a fairly new technique, we can not know much about really long-term effects. In the United States, LASIK was approved in the late 1990s.

The LASIK Quality of Life Collaboration Project (LQOLCP)

lasikThe LASIK Quality of Life Collaboration Project (LQOLCP) is a collaboration between the U.S. Food and Drug Administration, the U.S. Department of Defense, and the National Eye Institute. It was launched in 2009 and examined patient-reported outcomes for LASIK. In 2014, the findings were published.

Here are some of the findings:

  • Up to 30% of participants with no symptoms of dry eyes before LASIK reported dry eyes at three months after surgery.
  • Up to 45% of participants with no visual symptoms before LASIK reported at least one visual symptom at three months after surgery. In the group that reported visual symptoms after LASIK, halos was the most common problem. Examples of other reported visual symptoms after LASIK were double vision, starbursts and glare.
  • Up to 35% of participants with no halos before LASIK reported halos at three months after surgery.
  • Less than 1% of study participants reported having a lot of difficulty with or inability to do usual activities without corrective lenses because of their visual symptoms after LASIK.

LASIK variants


PresbyLASIK is a type of LASIK developed for eyes with presbyopia. The success rate for PresbyLASIK is lower than the success rate for LASIK used to treat myopia, hyperopia and astigmatism.

Wavefront-guided LASIK

Classic LASIK makes simple corrections for myopia, hyperopia and astigmatism. With Wavefront-guided LASIK, the surgeon will instead make a spatially varying correction. The surgeon will guide the computer-controlled laser based on measurements from a wavefront sensor.

The goal with Wavefront-guided LASIK is to create an optically perfect eye.

A risk factor inherent to Wavefront-guided LASIK is that the laser needs to correctly register eye positions in all three dimensions and track the eye in all the possible directions of eye movement. If it doesn’t, pre-existing aberrations can be worsened instead of improved by the procedure.

In older patients, the potential benefits of Wavefront-guided LASIK may be outweighed by the risk of experiencing problems caused by scattering from microscopic particles in the eye.

Alternatives to LASIK

LASEK (Photorefractive keratetomy / PRK)

LASIK and LASEK is not the same thing, even though the names are easy to mix up. With LASIK, a permanent flap is created. With LASEK, the corneal epithelium is removed and discarded, and the eye will need to form new corneal epithelium after the surgery. No flap is created.

LASIK is usually less painful than LASEK when the eye is healing and vision usually recovers more quickly with LASIK. This is mainly because with LASIK, the laser ablation is carried out in the deep corneal stroma.

You can read more about LASEK in our LASEK article on this site.

Phakic intraocular lens

There are eyes with high refractive errors where neither LASIK nor LASEK is recommended. For such eyes, the phakic intraocular lens (PIOL) can be an option. The phakic intraocular lens is also used for eyes where the very thin cornea makes LASIK and LASEK unsuitable.

A PIOL is implanted surgically into the eye. The eyes natural lens is left in the eye and not altered.

Radial keratotomy (RK)

Radial keratotomy (RK) was developed in the 1970s. Today, the technique has largely been supplanted by newer methods (chiefly LASIK and LASEK) but it remains a fairly popular choice for the correction of astigmatism in certain patients. During RK, a diamond knife is used to make incisions that reach deep into the cornea.


This is a younger technique than LASEK and standard LASIK, and have borrowed elements form both methods.

The surgeon will cut the cornea’s outer layer, but instead of using the fine blade used for LASEK the surgeon will use a blunt, plastic oscillating blade.

Epi-LASIK will usually not involve using alcohol to loosen the epithelial sheet. A plastic blade is used instead. There are exceptions though, some Epi-LASIK surgeons do use alcohol to improve the quality of the flap.

After Epi-LASIK, a special contact lens is placed in the eye to keep the flap in place while the epithelial cells grow back.

This article was last updated on: April 24, 2016