Posts Tagged ‘Refractive Laser Surgery’

How does LASIK work?

Thursday, February 18th, 2010

LASIK is the most commonly performed refractive surgery procedure. You may hear people calling it “LASIX,” but the correct name is LASIK, which is short for “laser-assisted in situ keratomileusis.”

Why is it so popular? LASIK has advantages over other vision correction procedures, including a relative lack of pain afterward and the fact that good vision usually is achieved by the very next day.

An instrument called a microkeratome is used in LASIK eye surgery to create a thin, circular flap in the cornea. Another, newer way of making the flap is with a laser.

The surgeon folds the hinged flap back out of the way, then removes some corneal tissue underneath using an excimer laser. The excimer laser uses a cool ultraviolet light beam to precisely remove (”ablate”) very tiny bits of tissue from the cornea to reshape it.

When the cornea is reshaped in the right way, it works better to focus light into the eye and onto the retina, providing clearer vision than before. The flap is then laid back in place, covering the area where the corneal tissue was removed.

Both nearsighted and farsighted people can benefit from the LASIK procedure. With nearsighted people, the goal is to flatten the too-steep cornea; with farsighted people, a steeper cornea is desired. Excimer lasers also can correct astigmatism by smoothing an irregular cornea into a more normal shape.

ArrivaCostaRica.com is the primary web site for information about plastic surgery and dentistry in Costa Rica. See www.arrivacostarica.com

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Refractive Lens

Monday, December 28th, 2009

In refractive lens exchange (RLE) eye surgery, your eye’s natural lens is replaced with an artificial one to achieve sharper focus.

While RLE technically does not have FDA approval, some surgeons in certain circumstances will use the procedure off label.

This type of use is perfectly legal and sometimes a practical option for elective vision correction surgery, particularly for older people and younger people in some circumstances.

Refractive Lens Exchange for Older People

People who are middle-aged or older may have the beginnings of cataracts that eventually could worsen and cloud the eye’s natural lens. In time, these cataracts could become advanced enough to require cataract surgery and replacement of the eye’s clouded lens with an artificial or intraocular lens.

If you have early cataracts, you could choose to have a refractive lens exchange instead of waiting for the cataracts to advance enough to require cataract surgery. Artificial (intraocular) lenses likely can provide significantly better uncorrected vision at that point, especially if you now require vision correction with glasses or contact lenses.

But keep in mind that you often can receive Medicare or insurance coverage for cataract surgery, which is a necessity, but not for an elective vision correction procedure like RLE. Costs of refractive lens exchange can range from about $2,500 to $4,500 per eye or higher, depending on the type of artificial lens used.

A major appeal of RLE is represented in newer accommodating or multifocal intraocular lenses, traditionally used in cataract surgery, with their ability to restore distance vision as well as improve near vision that enables functions such as computer use and reading for aging eyes. Presbyopia affects all of us beginning at around age 40, when our eye’s natural lens grows more rigid and we lose the ability to focus at all distances (accommodation).

Refractive Lens Exchange for
Younger People

For extreme farsightedness (hyperopia) higher than +6.00 diopters, LASIK is generally not recommended, making refractive lens exchange a possible option.

If a traditional intraocular lens is used, distance vision can be corrected, but reading glasses would be needed. If an accommodating or multifocal intraocular lens is used, reading glasses may be needed infrequently. [See also: Intraocular lenses or IOLs]

While refractive lens exchange is relatively safe, you do need to consider that any surgery has risks that should be discussed in detail with your eye surgeon.

As an example, the FDA notes that the chances of a retinal detachment are slightly higher in people who have undergone refractive lens exchange, compared with the general population. Otherwise, risks are similar to what people undergoing cataract surgery would face. The procedure for refractive lens exchange also is identical to cataract surgery.

ArrivaCostaRica.com is the primary web site for information about plastic surgery and dentistry in Costa Rica. See www.arrivacostarica.com

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Astigmatism

Monday, November 23rd, 2009

“What is a stigmatism?” is a question that eye doctors hear every day, but actually it’s spelled “astigmatism.” Although astigmatism is the most common vision problem, most people don’t know what it is.

Astigmatism may accompany farsightedness or nearsightedness. Usually it is caused by an irregularly shaped cornea (called corneal astigmatism). But sometimes lenticular astigmatism results from an irregularly shaped lens, which is located behind the cornea.

Either kind of astigmatism can usually be corrected with eyeglasses, contact lenses, or refractive surgery.

What Causes Astigmatism?

Astigmatism occurs when the cornea is shaped more like an oblong football than a spherical baseball, which is the normal shape. In most astigmatic eyes, the oblong or oval shape causes light rays to focus on two points in the back of your eye, rather than on just one. This is because, like a football, an astigmatic cornea has a steeper curve and a flatter one.

In regular astigmatism, the meridians in which the two different curves lie are located 90 degrees apart. In irregular astigmatism, the two meridians may be located at something other than 90 degrees apart; or there are more than two meridians.

Regular astigmatism is usually easy to correct (see treatments below), but irregular astigmatism can be complicated and more difficult to correct, depending on the extent of the irregularity and its cause.

Usually astigmatism is hereditary: many people are born with an oblong cornea, and the resulting vision problem may get worse over time.

But astigmatism may also result from an eye injury that has caused scarring on the cornea, from certain types of eye surgery or from keratoconus, a disease that causes a gradual thinning of the cornea.

Astigmatism Treatment

Unless it is extreme, astigmatism can be compensated for satisfactorily with eyeglasses or contact lenses.

If your eyeglass or contact lens prescription contains three parts rather than one, your eyecare practitioner has found some astigmatism in one or both of your eyes. A prescription with three parts looks like this: -2.75 -1.25 x 90.

  • The first part indicates your main spherical correction, meaning the amount of power (in diopters) required in a lens to sharpen your visual acuity to an acceptable level, usually 20/20. In this example, the person has myopia and requires a negative (concave) lens to correct it.
  • Part two shows the extent of the astigmatism in diopters. Again, the minus sign means a concave lens is needed.
  • Part three is the axis (in degrees) of the cylinder required to bend certain light rays to compensate for the cornea’s oval shape.

Many people with astigmatism believe that they can’t wear contact lenses or that only rigid contact lenses (RGPs, also called GP lenses) can correct astigmatism.

This was true many years ago, but now soft toric contact lenses can correct astigmatism. Toric lenses have a special correction built into them and may also contain a prescription for nearsightedness or farsightedness if you need it.

While soft torics work well for many people, if you have severe astigmatism, you’ll likely do better with RGP contact lenses or eyeglasses. Your eyecare practitioner will advise you.

ArrivaCostaRica.com is the primary web site for information about plastic surgery and dentistry in Costa Rica. See www.arrivacostarica.com

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A Glimpse at Laser Eye Surgery

Sunday, March 8th, 2009

If, like many people who suffer from imperfect vision, you have had enough of breaking your glasses or losing your contact lenses, then you may have considered undergoing laser eye treatment. Offering you the chance to improve your quality of life, as well as giving you more freedom, it is becoming an increasingly common procedure to have.

A large proportion of people worldwide have already opted for laser vision correction. According to the testimonies, it has not only served to enhance the patients’ vision, but has also provided them with more independence and confidence in life. But, how does it work and what are the different treatments available?

Essentially, the procedure is open to those people who suffer from acute short or long-sightedness, or astigmatism – this where your cornea is an oval rather than spherical shape, meaning images are blurred at most distances.

Your optician will be able to determine whether you should undergo laser eye treatment. If they believe that this is the case, then most procedures can be carried out very quickly and efficiently, and are performed using a local anaesthetic.

Generally speaking, there are two types of laser surgery available; LASEK (Laser-Assisted-Epithelial Keratomileusis) and LASIK (Laser-Assisted-In-Situ Keratomileusis). Each procedure is carried out whilst the patient is awake; eye drops are applied to numb the eye.

With LASEK laser eye treatment the top layer of the cornea, the epithelium, is removed before an excimer laser is used to re-sculpt the cornea. Once this is completed, the surgeon then replaces the epithelium on the eye’s surface. To keep it in place a soft contact lens is inserted, which must be kept in for a few days after the treatment.

LASIK eye treatment, on the other hand, is the most commonly executed procedure globally and is suitable for a wide number of people. Time wise, it is also extremely efficient since it is possible for both eyes to be treated at the same time, whilst it only takes around 10 to 15 minutes to complete. Patients have additionally reported less discomfort following the treatment compared to other types of laser surgery.

The difference between LASIK eye surgery and LASEK is that the former does not remove the epithelium, but instead creates a flap using specific cutting techniques. And, once the laser treatment has been completed, the flat is simply replaced, which helps it to heal more naturally.

ArrivaCostaRica.com is the primary web site for information about plastic surgery and dentistry in Costa Rica.  See www.arrivacostarica.com

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The History Of Eye Surgery

Saturday, March 7th, 2009

Radial Keratotomy (RK), a precursor to LASIK, was performed by making incisions on the corneal surface to correct nearsightedness and farsightedness. These techniques were first studied by the Japanese, then improved upon by an eye doctor in the Soviet Union during the 1970s. He taught this to American doctors visiting the USSR. While not a perfect procedure, RK did decrease patients’ dependence on eyeglasses.

In 1976, IBM Corp. developed the excimer laser, used in LASIK procedures. The first American refractive surgery using an excimer laser was approved by the Food and Drug Administration (FDR) in 1996. This laser revolutionized vision correction with its ability to remove very thin amounts of corneal tissue, equal to approximately 1/200th the thickness of a human hair, in approximately 12 billionths of a second.

Advances in technology, including the ultrathin diamond micrometer cutting blade, the microscopic guidance systems and computers to track results did much to increase the popularity and effectiveness of laser vision correction.

Wavefront technology gave us Custom LASIK, where your diagnosis is done to a far more precise level than the traditional diagnosis for glasses prescriptions. Since the diagnostic data guides the treatment laser, your results are of higher quality than was obtained from earlier LASIK vision correction.

Today, LASIK has been performed successfully on millions of patients seeking significant vision improvement. This is due largely to rapid technological advancements that continue to improve the procedure in terms of speed, comfort, results and cost.

How LASIK Works
How does LASIK correct the refractive errors of nearsightedness, farsightedness, and astigmatism? A unique combination of technology and surgical skill makes it happen.

• In nearsightedness (myopia), the cornea is too steep. Light from distant objects is bent too much and focuses in front of the retina instead of on it. The highly advanced excimer laser, developed in the 1980s, slightly flattens the cornea according to your customized treatment plan.
• In farsightedness, or hyperopia, the cornea is too flat. Light from nearby objects is not bent enough and focuses behind the retina. The LASIK laser slightly steepens the cornea by removing tiny pieces from around the edges according to your treatment plan.
• Astigmatism occurs when the cornea is oval instead of round. An oval lens has two curvatures: a steeper one on its shorter side and a flatter one on its longer side. That means light coming from the same object is bent in two ways and vision is blurry. The LASIK laser makes the cornea rounder for clear vision.

ArrivaCostaRica.com is the primary web site for information about plastic surgery and dentistry in Costa Rica.  See www.arrivacostarica.com

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