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Refractive Surgery...

Refractive surgery and particularly laser eye surgery are becoming increasingly popular with people from all walks of life. Although we do not perform the surgery ourselves or have dealings with a specific company, we believe in providing people as much information as possible about the various procedures available so that our patients can make an informed choice as to whether this is the best option for them. Hopefully, the following will give you an introduction to the subject.

The Beginning of Refractive Surgery

Fifty years ago in Bogota, Columbia, Dr. Jose Ignacio Barraquer developed a method to perform refractive surgery. He determined that he could change the eye's refractive power by altering the shape of the cornea. This procedure was called keratomileusis.

Keratomileusis as it existed then is no longer performed today, but Barraquer's work laid the foundations for some of refractive surgery's modern techniques. Barraquer was the first to create a hinged corneal flap – the outermost 20 percent of the thickness of the cornea. He also introduced the microkeratome, the device used to create the flap.

Radial Keratotomy (RK)

The next development in refractive surgery was radial keratotomy, or RK. This procedure, refined by a Russian ophthalmologist in 1963, involves using a diamond scalpel blade to make usually four to eight tiny spoke-like incisions in the periphery of cornea. The incisions slightly weaken the peripheral cornea, causing it to bulge. This flattens the center of the cornea, thus reducing myopia.

Although safer than its predecessor, RK has its drawbacks. The resulting change in refractive error is felt to be less predictable because no one can control the way the incisions heal. As a result, RK may only reduce myopia, not completely eliminate it. Despite the surgery, RK patients may still need to wear glasses for distance. In addition, with time, RK can result in overcorrection.

Because of advances in laser technology, surgeons perform RK only on a select group of patients.

Photorefractive Keratectomy (PRK)

PRK, or photorefractive keratectomy, was the next advance in refractive surgery. Performed world-wide to correct myopia, hyperopia and astigmatism, PRK involves removing the epithelium, the surface layer of the cornea. Then a computer-controlled excimer laser reshapes the cornea of the affected eye.

Anesthetic drops in the eye ensure that the patient experiences as little discomfort as possible. The long-term visual results achieved are predictable and stable.

PRK has its drawbacks, too. Patients do experience discomfort for 24-48 hours while their epithelium regenerates. Some patients may have unstable vision for a few months. Others may experience varying degrees of corneal haze or cloudiness. Typically both eyes are not treated at the same time, though they may be. Patients typically wear bandage contact lenses for pain reduction for a few days while the epithelial tissue regenerates and use postoperative eyedrops for four months.

Automated Lamellar Keratoplasty (ALK)

In ALK, the surgeon uses the microkeratome to separate a layer of the cornea and create a flap. The flap is then folded back, and the microkeratome removes a thin disc of corneal stroma below. The thickness and diameter of this disc determines the change in refractive error. The surgeon then places the flap back into position. This procedure can correct large amounts of myopia and hyperopia. However, the resultant change is not as predictable as with other procedures.

LASIK

LASIK, or laser in situ keratomileusis, has been used for ten years to treat myopia, hyperopia and astigmatism - it is currently the most common form of refractive surgery. It was first performed in the United States under clinical trials in 1991.

In this procedure, the surgeon produces a hinged corneal flap composed of the outermost 20-25 percent of the cornea's thickness. The computer-controlled excimer laser then reshapes the underlying exposed cornea. This minimizes discomfort and promotes rapid recovery. The surgeon then puts the flap back into place.

LASIK resembles PRK in that both procedures use the excimer laser to change the refractive error. However, because the surgeon creates the flap, LASIK preserves the epithelium and outermost stroma (the outermost 20-25 percent of the thickness of the cornea). As a result, the surface of eyes treated with LASIK heals faster than those treated with PRK. Most patients achieve good vision the day following surgery. Furthermore, patients experience less discomfort. It is also possible to have both eyes done at the same time with LASIK.

LASIK requires more instrumentation than PRK, and additional surgical precision is necessary to handle the microkeratome. For further information about LASIK follow this link.

Micro-thin Prescription Inserts

Micro-thin Prescription Inserts INTACS™ are two small arcs of medical plastic that a surgeon places into the mid-periphery of the corneal stroma. Once in place, the inserts cause a slight stretching of the cornea and a subtle flattening of the corneal curvature. The change in curvature varies with the thickness of the inserts. To place the inserts, the surgeon must first create a small incision in the periphery of the cornea. The inserts are then placed. Finally, the surgeon closes the incision (a suture may sometimes be required). Once placed, the inserts can be removed or replaced by the surgeon if the patient's vision needs change.

Phakic Intraocular Lens (IOL)

Used to treat a wide range of hyperopia and myopia, this procedure involves inserting an implant called an intraocular lens (IOL) into the eye's anterior chamber – the area in front of the pupil - or posterior chamber – the area between the iris and the normal lens. A long history with lens design and implantation technique for cataract surgery is an advantage. But the rise of this procedure in patients without removal of cataracts raises a number of concerns, and there is the risk of infection inside the eye.

Clear Lens Extraction

Used to treat a wide range of hyperopia and myopia, this procedure involves removing the eye's lens and inserting an artificial lens. The process resembles that of cataract surgery; however in cataract surgery the lens is clouded, whereas in this surgery, the removed lens is clear. An advantage is that cataract surgery has been performed successfully for years and is a familiar procedure to many surgeons. There is more risk of infection inside the eye since this is an intraocular procedure. Also, clear lens extraction produces less accommodation (ability to see near without reading glasses) and possesses and increased risk of retinal detachment, especially in high myopia.

Multiple Procedures

Doctors will sometimes use two or more procedures to treat patients suffering from high to severe myopia. For instance, ophthalmologists have inserted phakic IOLs and then performed LASIK to achieve the desired refraction in eyes with more than -15D of myopia pre-operatively. Surgeons have also performed initial LASIK procedures then inserted ICRS to correct residual errors.

However, patients should understand that the use of multiple procedures is a relatively new option in many countries. Very little study data has been accumulated on the long-term effects of multiple procedures, and patients may need to look harder to find a surgeon currently performing such procedures in combination with one another.

Other Procedures

Orthto-keratology uses contact lenses to temporarily remold the cornea to reduce or correct myopic or astigmatic refractive errors. Patients wear orthokeratology lenses nightly or on alternate nights after the ideal corneal shape has been achieved, thereby eliminating the need for spectacles or contact lenses the next day. This non-surgical procedure has the advantage of reversibility. However, patients should be prepared to visit a doctor 4-10 times during the initial 3-6 month period in order to ensure that the cornea is properly shaped. In addition, retainer lens wear is essential to prevent the cornea from reverting to its natural shape. Orthokeratology works best on eyes with low myopia or astigmatism and is rarely effective for moderate to high refractive errors. The procedure also does not work as effectively on very steep or very flat corneas, and patients who are contact lens intolerant may not eligible.

Candidates for laser surgery normally have to be at least 18 years old, have stable vision and no abnormalities of the cornea or external eye. More information about laser eye surgery can be found at the following sites: