Medical Ophthalmology » Excimer Laser

How Laser Eye Surgery Works – Lasik and Photorefractive Eye Surgery

admin — Fri, 29 Jan 2010 20:48:34 +0000

People with eye-related problems are becoming more and more interested in laser eye surgery and its benefits because this is known to be the most exciting ophthalmologic procedure.

To be more precise, this is a refractive eye surgery that can correct all types of refractive errors such as: astigmatism (distorted vision), myopia (nearsightedness) and hyperopia (farsightedness).

Even if the medicine offers various types of surgical techniques for correcting refractive errors, the laser eye surgery was labelled by the American Academy of Ophthalmology the most technically advanced and precise one.

The excimer laser was the first laser ever approved for eye surgery and it’s used to correct myopia. Now, this laser is used in two different procedures: Laser in situ Keratomileusis (LASIK) and Photorefractive Keratectomy (PRK).

Photorefractive Keratectomy (PRK)

The surgeon maps and measures the patient’s eye before the procedure in order to analyse the problem. Then, he uses a few local anesthetic eye drops and reshapes the cornea eliminating tiny amounts of tissue from the outer surface.

Next, the doctor uses an ultra violet beam of light and cuts notches the size of human hair. Each pulse of light can remove a 39 millionth of an inch of cornel tissue in only 12 billionths of a second.

According to same studies, only 5% of the patients still use permanent glasses after the surgery while 15% need visual aids only when driving.

Laser in situ Keratomileusis (LASIK)

The LASIK procedure is more complicated than PRK but it’s a solution for solving all types of myopia.

The surgeon uses the Microkeratome to cut a corneal tissue flap in order to replace it. Everything depends on the doctor because with LASIK he has to make a very precise incision.

The patient only feels a little discomfort and sometimes an irritation but those won’t last too long. In most cases, the patients returned to their normal life in only two or three days.

With LASIK there can be only one side effect and that is occasional glare at night.

Anyway, everyone should know that even if the results are said to be permanent, the age can influence the final results and in some cases the doctor may even suggested re-surgery.

By: Ricky Lim

The History LASIK Surgery

admin — Wed, 27 Jan 2010 00:41:10 +0000

Almost everyone today has heard about Lasik eye surgery, but it wasn’t long ago that it was viewed as a brand new and revolutionary innovation. Lasik is actually an acronym that stands for laser assisted in-situ keratomileusis. It was development thanks to several advances in ophthalmologic technology, the first of which was the microkeratome blade invented in by Spanish ophthalmologist Jose Barraquer in the 1950s.

The microkeratome is an instrument containing an ultra-fine oscillating blade that is used to cut a thin flap in the eye’s cornea. In the decades that followed the invention of the microkeratome advances in laser technology would develop that enabled the eventual creation of the Lasik procedure.

The Excimer Laser

The first successful, working laser was tested in 1960. Researchers afterwards began developing more precise and powerful lasers. In the 1970s the Excimer laser was invented and it became one of the most crucial innovations in the field of ophthalmology.

The thing that made the Excimer laser unique was that, unlike previous lasers, it did not burn through tissue in order to make incisions. Rather it delivered enough energy to the targeted area that it actually caused the molecular bonds holding the tissue together to disintegrate into the air. Thus it was able to make ultra-precise cuts without burning tissue and risking possible thermal damage to surrounding areas. This meant that eye surgeries could now be conducted in a safer and more precise manner.

In the 1980s, Dr. Ioannis Pallikaris pioneered the concept of using the microkeratome invented by Barraquer in the 50s in conjunction with the Excimer laser. The microkeratome was used to cut the initial corneal flap. Once the cornea was accessed adn analyzed through corneal topography, the Excimer laser was used to do the actual re-shaping. Dr. Pallikaris himself conducted the first Lasik procedure in 1989.

LASIK Surgery Today

Since 1989 laser technology has only become more complex and precise. New procedures have made even the long-used microkeratome blade obsolete. In procedures such as epi-Lasik and IntraLase, a laser blade is used instead of the metal one to cut the flap in the cornea. This results in more accurate incisions that cause less discomfort and pain.

By: Ryan Frank

How Lasers are Revolutionizing Surgical Procedures

admin — Sat, 14 Nov 2009 19:16:55 +0000

The laser existed in theory long before it existed in reality. Albert Einstein was exploring the concept as early as 1917 when he was writing his seminal study on The Quantum Theory of Radiation. But even after the first working laser was successfully tested in 1960, people were skeptical about whether light could be used as a physical medical instrument. Less than five decades later, however, the laser has become one of the most versatile tools in the various fields of medical surgery.

Lasers have a variety of unique physical properties, which can be finely adjusted and changed in order to accomplish different surgical tasks. The light color and intensity of a laser and the way in which it interacts with the targeted tissue can be controlled, so that it becomes one the most delicate and precise instruments that a surgeon can have at his or her disposal.

The most well known surgical field in which lasers have made a huge impact is in the field of ophthalmology, or eye surgery. The excimer laser, which was invented in 1970 by Nikolai Basov, was especially useful. Rather than burn through tissue, the excimer laser conducts enough energy towards a targeted area so that it breaks down the bonds that hold tissue together. This allows ophthalmologists to target precise and often extremely thin layers of tissue without running the risk of damaging surrounding tissue.

But lasers have been used in other kinds of surgery as well. Laser scalpels, for example, have become one of the most precise and useful tools when there’s the need for making exact, delicate incisions during surgery. Laser scalpels are usually composed using carbon dioxide lasers. They are highly focused and accurate, enabling doctors to make cuts at the exact same, constant depth, whereas conventional metal scalpels run the risk of cutting too deeply. Also, lasers cauterize blood vessels even as they cut through tissue, thus preventing excessive blood loss.

Lasers have helped by eliminating the need for certain kinds of surgeries. For example, the open chest surgery that used to be required for de-clotting a patient’s arteries is no longer the only option available. The miniaturization of laser technology has made it possible to access a patient’s arteries by inserting a tiny optical fiber array containing a small laser through a patient’s vein, on the arm or leg. Using the optic fiber as a guide, doctors can travel through a patient’s veins to the arteries and fire the laser to destroy the harmful plaque.

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By: Ryan Frank

How Can a Laser Correct Your Vision?

admin — Sun, 25 Oct 2009 10:54:06 +0000

Not all lasers could correct your vision. Some could destroy it. There are a great many different types of laser, all man-made for different purposes. The one used for vision correction is called the Excimer laser – a name which means little to anyone except the people who first developed this type of laser. They made the word up, from two other words: excited and dimer. The story as to why is not relevant to the exciting world of LASIK.

Eye surgery, like every type of surgery, has been transformed by lasers. The excimer laser which does Custom LASIK, PRK, IntraLase, LASEK, and epi-LASIK procedures comes as part of a system of sophisticated technology and is a major investment for the eye surgeon.

How is a Laser Different From Other Lights?

Laser lights:

· Travel in rays that are parallel to each other;

· Are directional; and

· Have a single vibration.

Lasers are focused lights, rather than scattered like headlights or flashlights. That is why they make good classroom pointers. It’s also why they are excellent for eye surgery, because they can be made to come to a microscopically tiny focus.

Lasers and Heat

All lights generate heat and all hot things give off light. Light and heat are two aspects of the same energy. Some lasers are so hot they can slice through a block of steel. Some lasers used in dentistry and medicine are referred to as “cool” lasers, and the excimer laser is one of those. Cool lasers are both inherently cooler than some other types of laser, and also deliberately cooled for medical use.

Lasers and Color

Since all lasers have just one vibration level, they are a single color. Some have visible colors and some are infrared or ultraviolet – their vibration is beyond our visible color spectrum. Excimer lasers are ultraviolet.

How the Excimer Laser Works

The total vision correction system containing the excimer laser includes a patient bed, a computer and monitor, a tracking device to keep the laser targeted on each eye’s treatment area, a microscope for the eye surgeon to see your eyes highly magnified, a seat for the surgeon, and some tools and implements.

By the time you are on the patient bed for your vision correction, your two eyes have been precisely diagnosed as to their refractive errors. That is the first part of a Custom LASIK surgery, done before the day of your treatment. Your treatment plan is based on two 3-D maps generated by the diagnostic Wavefront equipment. They are microscopically exact maps of each eye’s contours and shape.

The excimer laser is programmed to follow these two maps during treatment, subject to your eye’s surgeon’s control. First a thin flap of surface tissue is folded back on the cornea (front transparent part of the eye), to expose the next layer down, the stroma. Then the excimer laser is directed on the pre-determined treatment area, and quickly vaporizes tiny pieces of unwanted tissue, at pre-set depths.

A New Corneal Contour

Your eye doctor planned the tissue vaporization so as to reshape the cornea. The cornea bends (refracts) light entering the eye, and in a 20/20 eye focuses it on the retina (“camera film”) at the back of the eye. Modifying its curvature changes the cornea’s degree of light refraction.

· If you are nearsighted (myopic), your eye surgeon will use the excimer laser to remove pieces in the center of the cornea. That slightly flattens the corneal curvature, and now light will not be refracted quite so much. You will have clear distance vision.

· If you are farsighted (hyperopic), your eye doctor will remove tissue from the periphery of the cornea, to slightly steepen its curvature. Now light will be refracted a bit more and you’ll have clear close-up vision.

· If you are astigmatic, your eye surgeon will remove tissue in an individual way according to your eye’s particular oval shape, to create a more round shape. An astigmatic eye is like a football, with a lengthwise flatter curvature and a crosswise steeper curvature. After it is made round, light will be refracted in only one way instead of two.

Lower and Higher Order Aberrations

No treatment plan is as simple as the above makes it sound. Many people are both astigmatic and myopic, for instance; and we all have tiny imperfections called Higher Order Aberrations. They are subtle defects like halos around light sources, poor night vision, and ghosting – faint duplicate images.

Myopia, hyperopia and astigmatism are the three Lower Order Aberrations. Custom LASIK corrects both higher and lower order aberrations. That allows you to (a) see more, because you have clarity at all distances; and (b) see better, because none of those subtle defects get in the way.

If you are considering a LASIK procedure, the best thing you can do to obtain excellent results is to choose a well-qualified eye surgeon. The best LASIK surgeons screen their patients very rigorously because it is in nobody’s best interest to perform a procedure on somebody who is a poor candidate for it. So do some homework before you choose your LASIK surgeon, and choose one who has many years of experience and has done several thousand procedures of the type you need.

By: Jennifer Kimberley