LASIK- Laser Eye Surgery

Introduction | Anatomy | Causes

Introduction

LASIK (Laser-assisted in situ Keratomileusis) is a type of laser eye surgery. It is used to correct myopia, hyperopia, and astigmatism. Myopia is nearsightedness, hyperopia is farsightedness, and astigmatism is a focusing abnormality. LASIK surgery is an alternative to wearing glasses or contact lenses. LASIK surgery is a short procedure that is associated with minimal pain and short recovery times.

Anatomy

Your eyes and brain work together with amazing efficiency. Light rays enter the front of your eye and are interpreted by your brain as images. Light rays first enter your eye through the cornea, the “window” of your eye. The cornea is a clear dome that helps your eyes focus.

The anterior chamber is located behind the cornea and in front of the iris. The anterior chamber is filled with a fluid that maintains eye pressure, nourishes the eye, and keeps it healthy. The iris is the colored part of your eye. Eye color varies from person to person and includes shades of blue, green, brown, and hazel. The iris contains two sets of muscles. The muscles work to make the pupil of your eye larger or smaller. The pupil is the black circle in the center of your iris. It changes size to allow more or less light to enter your eye.

After light comes through the pupil, it enters the lens. The lens is a clear curved disc. Muscles adjust the curve in the lens to focus clear images on the retina. The retina is located at the back of your eye.

Your inner eye, or the space between the posterior chamber behind the lens and the retina is the vitreous body. It is filled with a clear gel substance that gives the eye its shape. Light rays pass through the gel on their way from the lens to the retina.

The retina is a thin tissue layer that contains millions of nerve cells. The nerve cells are sensitive to light. Cones and rods are specialized receptor cells. Cones are specialized for color vision and detailed vision, such as for reading or identifying distant objects. Cones work best with bright light. The greatest concentration of cones is found in the macula and fovea at the center of the retina. The macula is the center of visual attention. The fovea is the site of visual acuity or best visual sharpness. Rods are located throughout the rest of the retina.

Your eyes contain more rods than cones. Rods work best in low light. Rods perceive blacks, whites, and grays, but not colors. They detect general shapes. Rods are used for night vision and peripheral vision. High concentrations of rods at the outer portions of your retina act as motion detectors in your peripheral or side vision.

The receptor cells in the retina send nerve messages about what you see to the optic nerve. The optic nerves extend from the back of each eye and join together in the brain at the optic chiasm. From the optic chiasm, the nerve signals travel along two optic tracts in the brain and eventually to the occipital cortex.

Causes

Uses

LASIK is an alternative to wearing glasses or contact lenses for myopia, hyperopia, and astigmatism. People with myopia have nearsightedness and difficulty seeing detail at a distance. People with hyperopia have farsightedness and difficulty seeing nearby objects. Astigmatism is a focusing problem that can make nearby, distant, or both nearby and distant vision appear blurry. Such conditions may result because of the way the cornea is shaped. Imperfections in the cornea that affect the way images are reflected on the retina are called refractive errors. LASIK is used to precisely shape the cornea to correct refraction.

Your doctor can let you know if you are a candidate for LASIK. LASIK is not appropriate for people with certain medical or eye conditions. Your doctor will explain the risks associated with the procedure. LASIK is only performed on people that are 18 years and older.

Preparation

Prior to surgery, your doctor will perform a thorough eye examination. If you wear contact lenses, your doctor will let you know how long you should stop wearing them before your surgery. You should not wear makeup, creams, lotions, or perfume the day before and the day of your surgery.

LASIK surgery is an outpatient procedure. It is a short surgery, usually less than 30 minutes.
You should arrange to have another person drive you home from the procedure.

Treatment

You will sit in a reclining chair for the procedure. Eye drops will be used to numb your eye. The area around your eye will be cleaned. A speculum device will be placed to keep your eye open.

A ring will be placed on your eye. High pressure will create a suction on your cornea. You may feel some discomfort or blurred vision during this part of the procedure. Your doctor will make an incision to create a flap on your cornea.

The laser will be positioned directly over your eye. You will be asked to stare at a light. Your doctor will use the laser’s high-energy light to vaporize cornea tissue to reshape it.

When the laser treatment is complete, the flap is replaced over your cornea. A protective shield will cover your eye to protect it while it heals. You should not rub or put pressure on your eye while it heals.

Immediately after surgery, your eye may burn, itch, or feel like there is something in it. You may experience mild pain, watery eyes, or blurred vision. Your eyes may be sensitive to light. You may see starbursts or halos around lights. These symptoms may last for a few days. You should contact your doctor if you experience severe pain or if your symptoms get worse instead of better.

Your doctor will monitor your healing progression with regular appointments. Your doctor will inform you about temporary activity restrictions and when you may resume wearing contact lenses. It may take three to six months for your vision to stabilize.

This information is intended for educational and informational purposes only. It should not be used in place of an individual consultation or examination or replace the advice of your health care professional and should not be relied upon to determine diagnosis or course of treatment.

The iHealthSpot patient education library was written collaboratively by the iHealthSpot editorial team which includes Senior Medical Author Dr. Mary Car-Blanchard, OTD/OTR/L and the following editorial advisors: Steve Meadows, MD, Ernie F. Soto, DDS, Ronald J. Glatzer, MD, Jonathan Rosenberg, MD, Christopher M. Nolte, MD, David Applebaum, MD, Jonathan M. Tarrash, MD, and Paula Soto, RN/BSN. The library commenced development on September 1, 2005 with the latest update/addition on April 5, 2010.

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LASIK- Laser Eye Surgery