LASIK and Vision Surgery
Corneal inlays and corneal onlays are tiny lenses or other optical devices that are inserted into the cornea to improve reading vision. Some of these devices resemble very small contact lenses.
The primary purpose of these devices is to improve near vision and reduce the need for reading glasses in older adults who have presbyopia.
As their names suggest, corneal inlays and onlays differ in where they are implanted within the cornea: corneal onlays are placed near the surface of the eye, directly under the thin outer layer of the cornea called the epithelium; inlays are placed deeper in the cornea — in the thicker middle layer called the stroma.
A cornea transplant replaces diseased or scarred corneal tissue with healthy tissue from an organ donor.
There are two main types of cornea transplants: traditional, full thickness cornea transplant (also known as penetrating keratoplasty, or PK) and back layer cornea transplant (also known as endothelial keratoplasty, or EK).
A graft replaces central corneal tissue, damaged due to disease or eye injury, with healthy corneal tissue donated from a local eye bank. An unhealthy cornea affects your vision by scattering or distorting light and causing glare and blurred vision. A cornea transplant may be necessary to restore your functional vision.
Corneal eye disease is the fourth most common cause of blindness (after cataracts, glaucoma and age-related macular degeneration) and affects more than 10 million people worldwide.*
More than 47,000 cornea transplants will be performed in the United States in 2013, according to an estimation by the Eye Bank Association of America. Since 1961, more than one million people have had their sight restored with a cornea transplant.
Until contact lenses were popularized in the 1950’s, eyeglasses for at least the past seven centuries had been the only practical way to correct refractive vision errors.
Now, several modern approaches to corrective eye surgery range from laser reshaping of the eye’s surface in procedures such as LASIK and PRK to surgical insertion of artificial lenses to correct eyesight.
In LASIK, PRK, and similar procedures, laser energy reshapes the curvature of the eye’s clear front surface (cornea) to alter the way light rays enter the eye. Artificial lenses surgically inserted into the eye also can refocus light rays to sharpen vision.
Refractive surgery is the term used to describe surgical procedures that correct common vision problems (nearsightedness, farsightedness, astigmatism and presbyopia) to reduce your dependence on prescription eyeglasses and/or contact lenses.
Currently, a laser procedure called LASIK (LAY-sik) is the most popular refractive surgery performed in the United States. But there are other types of refractive surgery — including other laser procedures and intraocular lens (IOL) procedures — that might be an even better choice for you, depending on your needs.
The articles below will help you learn more about your surgical options so you can better discuss them with your eye doctor if you are interested in elective vision correction surgery.
A successful LASIK procedure is determined largely by whether you meet certain patient criteria and if laser eye surgery is right for you.
LASIK and PRK outcomes are almost always favorable; however, not everyone is a good candidate for vision correction surgery.
The following laser eye surgery checklist is a good start to help you determine if LASIK or PRK is right for you.
LASIK and other types of laser eye surgery, such as PRK and LASEK, have excellent safety profiles and very high success rates. They are designed to treat myopia (nearsightedness), hyperopia (farsightedness) and astigmatism, and can allow you to live without glasses or contacts.
Sight-threatening complications such as significant loss of vision from LASIK surgery are extremely rare, and many side effects and laser eye surgery complications can be resolved with additional surgery or medical treatment.
Like any other surgery, however, there are potential risks, side effects and limitations you should be fully aware of before electing to undergo the procedure (or any type of procedure, for that matter). Choosing a skilled and experienced LASIK eye surgeon can help reduce these risks and enable you to achieve the best possible results from laser eye surgery.
The first step is to determine if you are a good candidate for vision correction surgery. Your eye doctor will perform a thorough diagnostic eye exam to determine your suitability for LASIK surgery. He or she will evaluate: the shape and thickness of your cornea; your refractive errors and pupil size; the moistness of your eyes (to check for dry eye syndrome); your general health and medical history; and any medications you are taking.
Even if you are not a good candidate for LASIK, don’t worry — you might still be able to have your vision fixed with other vision correction surgery such as PRK, LASEK or implantable lenses.
Even if you undergo LASIK or PRK as a young person and achieve perfect vision, you still will develop a condition called presbyopia, typically beginning between the ages of 40 and 50.
Presbyopia is the inability of the eye to focus at all distances, usually noticed when fine print starts to blur.
Some eye doctors disagree about what causes presbyopia. Most believe stiffening of the eye’s lens contributes to the condition. Other theories suggest that presbyopia also could be related to continued growth of the lens or atrophy of the muscles controlling the lens.
In the past, the usual remedy was to wear reading glasses or special multifocal lenses (bifocal orprogressive lenses) for presbyopia. But in modern times, surgical remedies for presbyopia also are available for qualified candidates.
One of the first effective surgical options for presbyopia correction involved producing what is known as “monovision” during LASIK. But other surgical procedures such as conductive keratoplasty or CK (see below) also have been approved by the FDA, which gives eye surgeons additional options for correcting this common vision problem.
Several other experimental devices and procedures also are under investigation, but not yet FDA-approved. Here is a rundown.