What is LASIK?



The vision correction procedure widely known as LASIK is actually nowadays a routine surgical procedure elected by many people with impaired vision who wish to eliminate the need for prescription glasses and/or contact lenses. The word LASIK is actually an acronym that stands for laser-assisted in situ keratomileusis. LASIK eye surgery is an ambulatory procedure that does not require a hospital stay. Shortly after the surgery, which generally lasts about five minutes per eye, most patients are able to walk out of the eye doctor's office on his or her own. It is recommended that patients are accompanied to the LASIK eye center considering the fact that a mild sedative is often used.

Before the doctor begins the procedure, numbing eye drops are going to be applied to the eyes so the patient doesn't experience a lot of discomfort during the procedure. A device that helps keep the eyes open is positioned beneath your eyelids to hold them wide open. While this sounds like it might be uncomfortable it usually is not. The LASIK surgeon creates a flap that allows the cornea--the outer lens of the eye--to be slightly lifted. A precision laser is utilized to create the flap. The doctor folds the hinged flap back so that the surface of the cornea can be corrected using a different type of laser known as an excimer laser. The excimer laser works by using an ultraviolet light beam to smooth the surface and remove microscopic pieces of tissue from the cornea in order to reshape it.

lasik diagramThe cornea can be described as the portion of the eye that focuses light to produce an image onto the retina. It functions a lot like the lens of a camera focuses and concentrates light to produce images on photographic film.  Most of the time the contour of the cornea is not optimal and the image projected onto the retina is blurred or distorted in varying degrees. These defects in the focusing ability of the eye are known as refractive errors. These errors lead to conditions that are known as: myopia, hyperopia and astigmatism.

Those individuals afflicted with myopia, or nearsightedness, cannot see distant objects as clearly as near objects.  People with the vision condition known as hyperopia, or farsightedness, have the opposite problem where they have much more trouble seeing near objects as clearly as far away objects. Astigmatism can be described as a distortion of the image on the retina resulting from irregularities on the cornea. Some people even suffer from astigmatism along with either nearsightedness or farsightedness. Both nearsighted as well as farsighted people today can enjoy improved vision as the result of LASIK. 

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. - U.S. FDA

The basic goal of the LASIK procedure is to return the cornea to a normal range of focusing power. Precise and controlled removal of corneal tissue by a special laser reshapes the cornea changing its focusing power. After the cornea is reshaped after a successful procedure, it will do a better job of focusing light onto the retina, which will result in sharper, clearer vision.

The vast majority of patients experience some mild discomfort for a day or two after laser eye surgery. This is one of the main advantages of today's LASIK compared to vision correction procedures from several years ago which often resulted in pain that lasted for several days. Older technologies such as Radial Keratotomy (RK) are surgical procedures where a blade is used to cut the cornea and change its shape and contour. Doctors often prescribe eye drops after LASIK in order to prevent dry eyes which is one of the most common complaints.

There are a few basic criteria that need to be met before even considering LASIK. As with any medical procedure, there are certain risks that one ought to be aware of and take into consideration as a means to avoid the most common LASIK complications.

Most LASIK doctors advise that patients be at least 21 years old. One of the main reasons for this is that it is important that the person's vision is somewhat stable. Younger people's eyesight can change quite a bit as evidenced by the sometimes frequent changes in their eyeglass and contact lens prescriptions. It is common for a person's vision to stabilize at some point during their twenties. An optometrist is best able to determine, based on the eyeglass prescription history, whether the vision is stable enough for a corrective vision procedure.

There are several conditions which would preclude a person from eligibility for LASIK. Conditions such as chronic dry eyes and conjunctivitis must be dealt with and resolved before surgery is possible. Other more serious ailments such as cataracts and glaucoma may totally disqualify a patient.

Pregnancy and its accompanying hormonal changes can have an impact on a woman's vision so it is not a good time to diagnose vision deficiencies. Also, pregnancy in general is not a good time to proceed with any type of elective surgery since there is always the chance of complications or infection which have the potential to negatively affect the fetus.
Different types of LASIK eye surgery have evolved over the past couple of decades and the technology is always improving. You can read the following articles to find out some general information on some of the different types of laser vision correction that have been developed.

  • Bladeless LASIK - Learn about the potential benefits of this type of surgery.
  • Custom LASIK - Also referred to as wavefront LASIK, geared towards correcting higher order aberrations.
  • Epi LASIK - potentially less invasive than traditional LASIK.




FDA Website for information on LASIK:

fda - US food and drug administration