Radial Keratotomy or RK and Photorefractive Keratectomy or PRK are other refractive surgeries used to reshape the cornea. In RK, a very sharp knife is used to cut slits in the cornea changing its shape. PRK was the first surgical procedure developed to reshape the cornea, by sculpting, using a laser. Later, LASIK was developed. The same type of laser is used for LASIK and PRK. Often the exact same laser is used for the two types of surgery. The major difference between the two surgeries is the way that the stroma, the middle layer of the cornea, is exposed before it is vaporized with the laser. In PRK, the top layer of the cornea, called the epithelium, is scraped away to expose the stromal layer underneath. In LASIK, a flap is cut in the stromal layer and the flap is folded back.
Farsightedness- Farsightedness is another name for Hyperopia or Hypermetropia. Many Farsighted patients have difficulty seeing things up close, and often have crisp-acute distance vision.(19 January 2007 - Online blog Dr. Boothe Laser Center )
Excimer Laser- An excimer laser refers to a cool laser. Excimer lasers use cool beams of ultraviolet light to evaporate corneal tissue during vision correction.
Corneal Epithelium- The corneal epithelium is the thin, protective layer encasing the eyeball. Prior to LASIK eye surgery, the epithelium must be lifted or polished away to expose the underlying cornea. The epithelium is regenerative and heals quickly.
Acuity- Acuity refers to the sharpness or clarity of your vision.
Cornea- The cornea is the transparent front portion of the eyeball that covers the iris and pupil; it is continuous with the sclera.
Farsightedness, Hyperopia:
Farsighted people can usually see things that are far away better than things that are close. A farsighted prescription will have a positive number under the sphere column.Dr. Boothe Eye Care
Keratectomy- Keratos is the greek word for cornea, and ectomy means to remove. Together they mean to remove corneal tissue.
Precision Surgery
PRK is an outpatient procedure generally performed with local anesthetic eye drops. This type of refractive surgery gently reshapes the cornea by removing microscopic amounts of tissue from the outer surface with a cool, computer-controlled ultraviolet beam of light. The beam is so precise it can cut notches in a strand of human hair without breaking it, and each pulse can remove 39 millionths of an inch of tissue in 12 billionths of a second. The procedure itself takes only a few minutes, and patients are typically back to daily routines in one to three days.
Before the procedure begins, the patient's eye is measured to determine the degree of visual problem, and a map of the eye's surface is constructed. The required corneal change is calculated based on this information, and then entered into the laser's computer.
Since 1995, a limited number of laser systems has been approved by FDA to treat various refractive errors, both with PRK and LASIK.
According to FDA's Center for Devices and Radiological Health, clinical studies showed that about 5 percent of patients continued to always need glasses following PRK for distance, and up to 15 percent needed glasses occasionally, such as when driving. In addition, many patients experienced mild corneal haze following surgery, which is part of the normal healing process. The haze appeared to have little or no effect on final vision, and could only be seen by a doctor with a microscope. Some patients experienced glare and halos around lights. These conditions, however, diminished or disappeared in most patients in six months. For about 5 percent of patients, however, best-corrected vision without corrective lenses was slightly worse after surgery than before. In view of these findings, FDA and the Federal Trade Commission (which oversees advertising) issued a letter to the eye-care community in May 1996 warning that unrealistic advertising claims, such as "throw away your eyeglasses," and unsubstantiated claims about success rates could be misleading to consumers. (02 March 2009 Dr. Boothe )
Dr. Boothe Eye Center article
Dr. Boothe Eye Center
At Laser Eye Center, our surgeons are the first to utilize LADARWavey® CUSTOMCORNEA® wavefront technology to measure and address both lower and higher order aberrations (visual imperfections in the eye's optical system). Unless both lower and higher order aberrations are addressed during laser vision correction, the quality of your vision may not be ideal, even if you have post-operative vision of 20/20.
Pupil- The pupil is the dark opening in the visible eye. It will open when more light is needed to see, and it will get smaller if less light is needed to see.( 15 August 2007 Blog article Dr. William Boothe )
