Types of LASIK Surgery

Ever wondered what are the main types of LASIK surgery? Find out what LASIK eye surgery means and what types of surgery can be performed.

The Types Of Lasic Or Refractive Eye Surgery

LASIK (Laser-Assisted In Situ Keratomileusis) is not the only kind of operation. There are several types of laser refractive surgery for the purpose of reducing dependence on or eliminating the need for glasses and or contact lenses.

If you are considering corrective eye surgery, you should understand the different types of corrective eye surgery options available.

Radial Keratotomy or RK and Photorefractive Keratectomy or PRK and thermokeratoplasty for example are other refractive surgeries available to reshape the cornea. Let’s review each variation of treatment and laser refractive surgery.

There are several variations of Refractive Eye Surgery used to correct the shape of the cornea, required because the eye is not perfectly contoured causing the image on the retina to be out-of-focus or distorted.

Such imperfections in the focusing ability of the eyes are called refractive errors.

The most common types of refractive errors are myopia, hyperopia, and astigmatism.

• Myopia (called nearsightedness) causes difficulty seeing distant objects as clearly as close objects.
• Hyperopia (called farsightedness) causes difficulty seeing close objects as clearly as more distant objects.
• Patients with Astigmatism have distortion of the image caused by irregularities in the shape of the cornea.

Many patients can have a combination of these three conditions. In addition to contact lenses or spectacles, surgical procedures called refractive surgery are becoming more and more common to improve the focus of the eyes.

LASIK is the acronym for Laser-Assisted in Situ Keratomileusis.

It is a surgical procedure that permanently changes the shape of the clear covering of the front of the eye called the cornea.

Surgery is performed using an excimer laser.

A knife, known as a microkeratome, is used to cut a flap in the cornea leaving a hinge at one end of this flap. When folded back the flap reveals the middle section of the cornea known as the stroma.

Pulses from the computer-controlled laser vaporize a predetermined section of the stroma before the flap is replaced. This process reshapes the cornea changing its focusing power.

Other types of refractive surgery used to reshape the cornea include Radial Keratotomy (RK) where a very sharp knife is used to cut slits in the cornea changing its shape AND Photorefractive Keratectomy (PRK) which was the original surgical procedure developed to reshape the cornea, by sculpting, using a laser.

The same type of laser is used for LASIK and PRK. In PRK, the epithelium is scraped away to expose the stromal layer, whilst in LASIK, a flap is cut in the stromal layer and the flap is folded back. A further type of refractive surgery is thermokeratoplasty in which heat from a different type of laser is used to reshape the cornea. So let’s examine the differences in more detail.

Excimer Laser Procedures

Excimer Laser Procedures include those where an excimer laser is used to reshape the clear part of the eye covering the iris and pupil called the cornea to change its focusing abilities.

Laser-Assisted In Situ Keratomileusis (LASIK) treats myopia, hyperopia, and astigmatism. The surgeon cuts a flap in the cornea’s middle layer consisting of lamellae and cells, known as the stroma which makes up the largest portion of the cornea. Next, the surgeon uses an instrument that uses short wave (ultraviolet)light (an excimer laser)to vaporize and remove tissue particles.

Epi-LASIK is similar to LASEK in that the flap is cut only in the epithelium, but the surgeon uses neither a blade nor alcohol. Instead, the surgeon uses an epikeratome, which is a separator that creates an epithelial sheet. Because no alcohol is involved, patients are likely to feel less pain than in alcohol procedures and will generally heal faster. For people with less steep corneas from low myopia.

ALL LASER LASIK differs from LASIK surgery in that an additional laser is used instead of a microkeratome to create the flap in the epithelium.

Photorefractive Keratectomy (PRK) is a laser eye surgery procedure where the surgeon uses an excimer laser to remove tissue from the surface of the cornea resulting in a new shape to correct the vision. This procedure usually takes less than one minute per eye, with no flap cut into the epithelium as with LASIK.

Laser Epithelial Keratomileusis (LASEK). This is a newer procedure, similar to LASIK, with a longer healing time, however, the surgeon does not cut through the epithelium and part of the strom he only cuts a flap in the cornea’s outer layer of cells (the epithelium). The surgeon then loosens the edge of the flap with alcohol. This procedure is mainly for those with thin or flat corneas who would not be suitable candidates for LASIK, which requires more corneal tissue.

Non-Excimer Laser Procedures

Non-laser refractive procedures include reshaping the eye with low-heat radio waves, inserting artificial lenses into the eye, or cutting into the eye’s surface.

Astigmatic Keratotomy (AK) is used to treat mild astigmatism. The surgeon cuts the cornea in those areas that are too bulgy, to flatten them to a more normal curve. Many patients undergo Astigmatic Keratotomy in addition to other corrective eye surgery, although some excimer lasers can now correct astigmatism in procedures such as LASIK and PRK making this less common. In a version of AK known as Limbal Relaxing Incisions (LRI), the surgeon cuts the area connecting the cornea and sclera where the white and colored areas of the eye meet to allow the cornea to heal to a more become more rounded shape.

Conductive Keratoplasty (CK). This procedure uses heat from radio waves to shrink collagen in the periphery of the cornea. The process steepens the cornea overall to correct farsightedness or presbyopia.

Scleral Expansion Bands (SEBs) These bands are implantation devices to treat presbyopia. The surgeon places four segments just below the surface of the outer coat of the eyeball that forms the visible white of the eye and surrounds the optic nerve at the back of the eyeball.

Intacs are plastic inserts that are used to correct degeneration and thinning of the cornea resulting in a cone-shaped bulge. The surgeon places the segments in the cornea to flatten it. The segments, though designed to be permanent, can be removed if necessary.

Intraocular Lenses (IOLs) replace the eye’s natural lens and are normally only implanted during cataract surgery. Some allow the lens to move in the eye or to see at near, intermediate, and distance ranges without reading glasses. Some eye surgeons will also exchange a patient’s healthy natural lens for an artificial lens or IOL as a way of providing vision correction in some situations.

Laser Thermal Keratoplasty (LTK) uses mild heat from a special laser to shrink collagen in the periphery of the cornea. This steepens the shape of the cornea overall to correct presbyopia.

Implantable Contact Lenses. This procedure involves the surgeon implanting a contact lens either attaching it to the iris or placing it behind the iris and in front of the eye’s natural lens. Patients can not feel the lenses and do not need to maintain them. This surgery is reversible should complications occur.

These are the main types of LASIK surgery.