What Lasik Vision Correction Surgery Is
Millions of people have been able to discard their eyeglasses or contact lenses after undergoing a Lasik laser vision correction surgery. But even though many people are aware that Lasik laser vision correction is a surgical procedure that employs a laser to improve eye sight, they are often unfamiliar with the details.
So, what exactly happens during the vision correction surgery done by a laser? Laser Assisted In Situ Keratomileusis (LASIK) can free corrective lens wearers from their dependence on contacts and glasses. Vision problems that include nearsightedness, farsightedness, and astigmatism can be corrected with this procedure.
LASIK utilizes a cold beam laser to reshape the corneal area as necessary in each patient in order to correct vision problems caused by imperfect corneas. Flaws in the shape of the cornea are responsible for these kinds of refractive errors. The Lasik laser procedure corrects the imperfections through reshaping the eye, allowing for clear vision.
This is done by making a small cut at the front of the eye to allow the laser to reach the area to be smoothed out. The surgeon cuts the flap using either a laser or a microkeratorne, which is a knife-like instrument. A small portion of tissue from the front of the eye is cut into a hinged-flap.
After the flap has been cut, the Lasik laser can access the cornea and begin repairing its shape, changing it into a correctly shaped cornea with normal function. Once the cornea has been reshaped, the flap is returned to its normal position and the surgery is pretty much completed.
Although adjustments made to the cornea's shape are permanent, other Lasik vision correction measures can usually be made if necessary. While patients considering Lasik vision correction surgery should focus on the benefits of the procedure, they also need to understand that there is always the possibility of risks and side effects.
This procedure is fast, normally pain free, and has few side effects or possible risks. Each eye takes less than a few minutes when the Lasik laser is used on it for vision correction surgery. Most often patients complain that their vision is hazy but this problem usually disappears within a few days.
Prior to the procedure, all candidates for Lasik laser vision correction are guided through the process and gain knowledge of the options, risks, and long-term benefits. Still needing to wear corrective lenses is the most common risk after the surgery has been completed.
A Lasik laser vision correction candidate should consult with his/her eye care professional who will be able to assist the person in making an informed decision with regard to the procedure. Patients will be more at ease with their decision if, in addition to knowing that the procedure will help them see better, they understand what Lasik is and how it works.
2008年6月30日星期一
ALTERNATIVE TO LASIK FOR VISION CORRECTION
According to the meshwork programme inform , after reports of defeated preoperative outcome of Lasik Surgery and ensuant warnings presented by bureau on LASIK surgery, whatever patients are fearing and indecisive to participate LASIK surgery for the communication of eye disease. Realizing that, whatever of the Optometrists of America, are considering of added alternatives that has been invented to form cornea of the eye.
“Vision rebuke surgery crapper be a enthusiastic choice for whatever patients, and jillions of grouping are mitigated with the results,” said Dr. Craig Hoeft, OD, of the Calif. Optometric Association. “But for those who are afraid and poverty to move until the bureau has more findings most Lasik and Vision ICL, a newer preoperative option, there are individual nonsurgical options that wage momentous results and are easy, easy and innocuous for many, whatever patients.”
Silicone hydrogel fleecy occurrence lense is digit of the field deciding to LASIK surgery. These lenses are caretaker semipermeable and crapper be attrited for 30 serial life without removal.
Another deciding is Corneal reshaping technology. This is also a non preoperative procedure. It reshapes the cornea daylong with specially fashioned pedal semipermeable therapeutic occurrence lenses that are inserted into the receptor before feat to bottom and distant in the morning.
There is still added deciding - unadaptable pedal semipermeable lenses (GP) or pedal semipermeable occurrence lenses. These are unadaptable lenses prefabricated of firm, imperishable impressible that transmits pedal into the eye. GP occurrence lenses are rigid, but they shouldn’t be potty with old-style “hard” occurrence lenses, which are today obsolete. GPs transfer more pedal to the receptor than do tralatitious fleecy occurrence lenses (although whatever newer polymer hydrogel fleecy lenses are same to GPs in pedal transmission).
Gas semipermeable occurrence lenses crapper also wage meliorate vision, durability, and installation status than fleecy occurrence lenses. They crapper be easier to clean, and since they’re long-lasting, they crapper be inferior pricey in the daylong constituent than fleecy lenses.
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“Vision rebuke surgery crapper be a enthusiastic choice for whatever patients, and jillions of grouping are mitigated with the results,” said Dr. Craig Hoeft, OD, of the Calif. Optometric Association. “But for those who are afraid and poverty to move until the bureau has more findings most Lasik and Vision ICL, a newer preoperative option, there are individual nonsurgical options that wage momentous results and are easy, easy and innocuous for many, whatever patients.”
Silicone hydrogel fleecy occurrence lense is digit of the field deciding to LASIK surgery. These lenses are caretaker semipermeable and crapper be attrited for 30 serial life without removal.
Another deciding is Corneal reshaping technology. This is also a non preoperative procedure. It reshapes the cornea daylong with specially fashioned pedal semipermeable therapeutic occurrence lenses that are inserted into the receptor before feat to bottom and distant in the morning.
There is still added deciding - unadaptable pedal semipermeable lenses (GP) or pedal semipermeable occurrence lenses. These are unadaptable lenses prefabricated of firm, imperishable impressible that transmits pedal into the eye. GP occurrence lenses are rigid, but they shouldn’t be potty with old-style “hard” occurrence lenses, which are today obsolete. GPs transfer more pedal to the receptor than do tralatitious fleecy occurrence lenses (although whatever newer polymer hydrogel fleecy lenses are same to GPs in pedal transmission).
Gas semipermeable occurrence lenses crapper also wage meliorate vision, durability, and installation status than fleecy occurrence lenses. They crapper be easier to clean, and since they’re long-lasting, they crapper be inferior pricey in the daylong constituent than fleecy lenses.
You can get ccna 640-802 exam test engine from exam4sure with $90.99.
2008年5月15日星期四
What is LASIK?
The eye and vision errors
The parts of the eye. Indicated are the conjunctiva, sclera, choroid, optic nerve, retina, chamber angle, lens, cilary body, vitreous humor, aqueous humor, iris, pupil, cornea. The cornea is a part of the eye that helps focus light to create an image on the retina. It works in much the same way that the lens of a camera focuses light to create an image on film. The bending and focusing of light is also known as refraction. Usually the shape of the cornea and the eye are not perfect and the image on the retina is out-of-focus (blurred) or distorted. These imperfections in the focusing power of the eye are called refractive errors. 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. Glasses or contact lenses are designed to compensate for the eye's imperfections. Surgical procedures aimed at improving the focusing power of the eye are called refractive surgery. In LASIK surgery, precise and controlled removal of corneal tissue by a special laser reshapes the cornea changing its focusing power.
(See the animation of the LASIK procedure and what should I expect before, during, and after surgery.)
Other types of refractive surgery
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.
Another type of refractive surgery is thermokeratoplasty in which heat is used to reshape the cornea. The source of the heat can be a laser, but it is a different kind of laser than is used for LASIK and PRK. Other refractive devices include corneal ring segments that are inserted into the stroma and special contact lenses that temporarily reshape the cornea (orthokeratology).
What the FDA regulates
In the United States, the Food and Drug Administration (FDA) regulates the sale of medical devices such as the lasers used for LASIK. Before a medical device can be legally sold in the U.S., the person or company that wants to sell the device must seek approval from the FDA. To gain approval, they must present evidence that the device is reasonably safe and effective for a particular use, the "indication." Once the FDA has approved a medical device, a doctor may decide to use that device for other indications if the doctor feels it is in the best interest of a patient. The use of an approved device for other than its FDA-approved indication is called "off-label use." The FDA does not regulate off-label use or the practice of medicine.
The FDA does not have the authority to:
* Regulate a doctor's practice. In other words, FDA does not tell doctors what to do when running their business or what they can or cannot tell their patients.
* Set the amount a doctor can charge for LASIK eye surgery.
* "Insist" the patient information booklet from the laser manufacturer be provided to the potential patient.
* Make recommendations for individual doctors, clinics, or eye centers. FDA does not maintain nor have access to any such list of doctors performing LASIK eye surgery.
* Conduct or provide a rating system on any medical device it regulates.
The first refractive laser systems approved by FDA were excimer lasers for use in PRK to treat myopia and later to treat astigmatism. However, doctors began using these lasers for LASIK (not just PRK), and to treat other refractive errors (not just myopia). Over the last several years, LASIK has become the main surgery doctors use to treat myopia in the United States. More recently, some laser manufacturers have gained FDA approval for laser systems for LASIK to treat myopia, hyperopia and astigmatism and for PRK to treat hyperopia and astigmatism.
The parts of the eye. Indicated are the conjunctiva, sclera, choroid, optic nerve, retina, chamber angle, lens, cilary body, vitreous humor, aqueous humor, iris, pupil, cornea. The cornea is a part of the eye that helps focus light to create an image on the retina. It works in much the same way that the lens of a camera focuses light to create an image on film. The bending and focusing of light is also known as refraction. Usually the shape of the cornea and the eye are not perfect and the image on the retina is out-of-focus (blurred) or distorted. These imperfections in the focusing power of the eye are called refractive errors. 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. Glasses or contact lenses are designed to compensate for the eye's imperfections. Surgical procedures aimed at improving the focusing power of the eye are called refractive surgery. In LASIK surgery, precise and controlled removal of corneal tissue by a special laser reshapes the cornea changing its focusing power.
(See the animation of the LASIK procedure and what should I expect before, during, and after surgery.)
Other types of refractive surgery
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.
Another type of refractive surgery is thermokeratoplasty in which heat is used to reshape the cornea. The source of the heat can be a laser, but it is a different kind of laser than is used for LASIK and PRK. Other refractive devices include corneal ring segments that are inserted into the stroma and special contact lenses that temporarily reshape the cornea (orthokeratology).
What the FDA regulates
In the United States, the Food and Drug Administration (FDA) regulates the sale of medical devices such as the lasers used for LASIK. Before a medical device can be legally sold in the U.S., the person or company that wants to sell the device must seek approval from the FDA. To gain approval, they must present evidence that the device is reasonably safe and effective for a particular use, the "indication." Once the FDA has approved a medical device, a doctor may decide to use that device for other indications if the doctor feels it is in the best interest of a patient. The use of an approved device for other than its FDA-approved indication is called "off-label use." The FDA does not regulate off-label use or the practice of medicine.
The FDA does not have the authority to:
* Regulate a doctor's practice. In other words, FDA does not tell doctors what to do when running their business or what they can or cannot tell their patients.
* Set the amount a doctor can charge for LASIK eye surgery.
* "Insist" the patient information booklet from the laser manufacturer be provided to the potential patient.
* Make recommendations for individual doctors, clinics, or eye centers. FDA does not maintain nor have access to any such list of doctors performing LASIK eye surgery.
* Conduct or provide a rating system on any medical device it regulates.
The first refractive laser systems approved by FDA were excimer lasers for use in PRK to treat myopia and later to treat astigmatism. However, doctors began using these lasers for LASIK (not just PRK), and to treat other refractive errors (not just myopia). Over the last several years, LASIK has become the main surgery doctors use to treat myopia in the United States. More recently, some laser manufacturers have gained FDA approval for laser systems for LASIK to treat myopia, hyperopia and astigmatism and for PRK to treat hyperopia and astigmatism.
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