LASIK Eye Surgery

  • Medical Author:
    J. Bradley Randleman, MD

    Dr. Randleman received his BA degree from Columbia University in New York City. He earned his MD degree from Texas Tech University in Lubbock, Texas, where he was elected to the Alpha Omega Alpha Medical Honor Society. He completed his residency training at Emory University, serving as Chief Resident in his final year. He then completed a fellowship in Cornea/External disease and refractive surgery at Emory University.

  • Coauthor: John F. Payne, MD
  • Medical Editor: Melissa Conrad Stöppler, MD
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Laser Eye Surgery Slideshow Pictures

LASIK Eye Surgury - Risk

Finding the Right Doctor

If you are considering refractive surgery, make sure you:

  • Compare. The levels of risk and benefit vary slightly not only from procedure to procedure, but from device to device depending on the manufacturer, and from surgeon to surgeon depending on their level of experience with a particular procedure.
  • Don't base your decision simply on cost and don't settle for the first eye center, doctor, or procedure you investigate. Remember that the decisions you make about your eyes and refractive surgery will affect you for the rest of your life.
  • .....

Quick GuideLASIK Eye Surgery: Better Vision with Laser Surgery

LASIK Eye Surgery: Better Vision with Laser Surgery

What is LASIK?

LASIK stands for Laser in Situ Keratomileusis, which means using a laser underneath a corneal flap (in situ) to reshape the cornea (keratomileusis). This procedure utilizes a highly specialized laser (excimer laser) designed to treat refractive errors, improve vision, and reduce or eliminate the need for glasses or contact lenses. This laser procedure alters the shape of the cornea, which is the transparent front covering of the eye. Though the excimer laser had been used for many years before, the development of LASIK is generally credited to Ioannis Pallikaris from Greece around 1991.

What is MELAS?

MELAS is a rare genetic disorder which results in stroke and dementia. MELAS is an abbreviation that stands for Mitochondrial Encephalopathy, Lactic acidosis, and Stroke-like episodes.

What causes MELAS?

MELAS syndrome is caused by mutations in the genetic material (DNA) in the mitochondria. While most of our DNA is in the chromosomes in the cell nucleus, some of our DNA is in another important structure called the mitochondrion (plural: mitochondria).

The mitochondria are located outside the nucleus in the cell's cytoplasm. Each mitochondrion has a chromosome made of DNA that is quite different from the better known chromosomes in the nucleus. The mitochondrial chromosome is much smaller; it is round (whereas the chromosomes in the nucleus are normally shaped like rods); there are many copies of the mitochondrial chromosome in every cell; and no matter whether we are male or female, we inherit all of our mitochondrial chromosome from our mother.

Much of the DNA in our mitochondria is used to manufacture proteins involved in the key function of mitochondria -- to produce energy and power the cells in our body.

How does LASIK work?

During the LASIK procedure, a specially trained eye surgeon first creates a precise, thin hinged corneal flap using a microkeratome. The surgeon then pulls back the flap to expose the underlying corneal tissue, and then the excimer laser ablates (reshapes) the cornea in a unique pre-specified pattern for each patient. The flap is then gently repositioned onto the underlying cornea without sutures.

What is refractive error?

In the human eye, the front surface (cornea) and lens inside the eye form the eye's "focusing system" and are primarily responsible for focusing incoming light rays onto the surface of the retina, much like the lenses of a camera focus light onto the film. In a perfect optical system, the power of the cornea and lens are perfectly matched with the length of the eye and images are in focus; any mismatch in this system is called a refractive error, and the result is a blurred image at some location.

What are the symptoms of MELAS?

As a result of the disturbed function of their cells' mitochondria, patients with MELAS develop brain dysfunction (encephalopathy) with seizures and headaches, as well as muscle disease with a build-up of lactic acid in the blood (a condition called lactic acidosis), temporary local paralysis (stroke-like episodes), and abnormal thinking (dementia).

How is MELAS diagnosed?

The diagnosis of MELAS is usually suspected on clinical grounds. However, confirmation of the diagnosis usually requires a muscle or brain biopsy. The muscle biopsy shows characteristic ragged red fibers; a brain biopsy shows stroke-like changes.

What are the primary types of refractive error?

Myopia (nearsightedness): In people with myopia, the mismatch in focusing power and eye length causes distant objects to be blurry and near objects to be clearer.

Hyperopia (farsightedness): In people with hyperopia, the mismatch in focusing power and eye length causes near objects to be blurry and distant objects to be relatively clearer.

Astigmatism: In people with astigmatism, either the corneal or lens shape is distorted, causing multiple images on the retina. This causes objects at all distances to appear blurry. Many people have a combination of either myopia or hyperopia with astigmatism.

How do glasses or contacts improve vision in people with refractive errors?

Glasses or contact lenses are used to compensate for the eye's refractive error by bending light rays in a way that complements the eye's specific refractive error. In contrast, LASIK and other forms of refractive surgery are intended to correct the eye's refractive error to reduce the need for other visual aids.

When do people with MELAS develop symptoms?

MELAS can affect people at very different times in life, ranging from age 4 to age 40 or more. However, most patients with MELAS syndrome show symptoms before they are 20 years old.

How is MELAS treated?

There is no known treatment for the underlying disease, which is progressive and fatal. Patients are managed according to what areas of the body are affected at a particular time. antioxidants and vitamins have been used, but there have been no consistent successes reported.

Are there other mitochondrial diseases?

Yes, mutations (genetic changes) in the mitochondrial chromosome are responsible for a number of other disorders aside from MELAS such as:

  • an important eye disease called Leber hereditary optic atrophy;
  • a type of epilepsy called MERRF which stands for Myoclonus Epilepsy with Ragged Red Fibers; and
  • a neuromuscular disease called the Kearns-Sayre syndrome.

MELAS and all other mitochondrial diseases were not well understood before it was discovered that they were due to mutations in the chromosomes of the mitochondria.

Medically Reviewed by a Doctor on 8/23/2016

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