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The principle of the laser

The term “laser“ does not just bundle words – the term is an acronym for “Light Amplification by Stimulated Emission of Radiation“ – it also bundles light. The allure of laser light lies in its coherence. All light waves pulsate in harmony and thus intensify each other. With the help of tiny semiconductor laser diodes, laser light can be created in almost any wavelength. Medical science also benefits from the wave frequency and the vibrations that oscillate in the same beat. Laser can thus be used with great precision in different surgical procedures- from neurosurgery to orthopedics, cardiology all the way to gynecology.

Application in the operating room

Big impact in small areas: The application of laser procedures in the operating room is increasing, because it causes minimal hemorrhage, enables surgeries in small or hard to reach areas in the body and minimizes the risk of infection or scarring. The laser is almost unbeatable due to the fact that it can precisely destroy a specific tissue by using the same wavelength, that this specific tissue absorbs. ”As a tool it has high precision during the removal of specific harder tissues for example, without damaging the surrounding tissue“, knows Dr. Martin Wehner of the Fraunhofer Institute. “You can achieve flat cuts that are smaller than 100 micrometers i.e., smaller than a human hair with the use of a laser. Selective and gentle surgeries are therefore possible.“ Especially during surgeries of internal organs, laser systems need to operate very intelligently, since the organs are in constant motion.

Dr. Carsten Philipp, President of the German Society for Laser Medicine, clarifies: “Laser can be used as a substitute for a scalpel, but often it is used to selectively destroy diseased tissue. You can say good-bye to the classic view of surgery, since you can apply the laser through puncture or endoscopically.“ In the field of urology for example, the minimally invasive treatment has become common practice, especially for enlarged prostate glands and kidney stones. Ablation procedures or selective photothermolysis are often applied in plastic and esthetic surgery. Here the light is sent in millisecond pulses or continuously into the tissue and only destroys certain textures in micro-or macro areas.

The most progressive development in laser application is found in Ophthalmology (refractive surgery). By now, with a newly developed procedure for the treatment of prespyopia, the cornea can be lasered. In near- and far-sightedness and astigmatism a modern procedure called ”Laser Epithelial Keratomileusis“ (LASIK) is being used. The external, thin cornea film is detached with alcohol and rolled to the side. Then the excimer laser (it uses electromagnetic radiation in the ultraviolet wave range) is used, but these procedures still don’t guarantee a 100 percent success rate and entail several risks.

In gastroenterology, the medical science of stomach and colon diseases, the most common use of the laser occurs during removal or reduction of tumors in the colon or the esophagus. These are just some of the many uses for laser.

Generally speaking, the characteristics of the laser, like the energy-or wavelength, determine its application area. An argon laser – a gas laser of the ionized rare gas argon – is especially suited for example to obliterate vasculature. It prefers to give off its energy to the blood pigment hemoglobin.

 
 

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The medical future of light

Already photodynamic therapy is expanding the spectrum of cancer treatments. It is used for several types of skin-and esophageal cancers. This procedure can also be helpful in the diagnoses of tumors: By administering a light sensitive substance and the subsequent irradiation, diseased tissue clearly stands out against healthy tissue. Using a similar principle, laser radiation can combat tumors. The patient receives a light sensitive substance to take in, which exclusively concentrates in degenerated cells. When the cells are irradiated with laser light, which precisely activates this substance, a cell poison is created. The growth of tumor cells is slowed down by this or the diseased cells are killed. These procedures continue to be on the rise.

In the near future, the developments in eye surgery will also take on more forms: The reason for presbyopia is the fact that the elasticity of the eye lens decreases with advancing age. With a new procedure, the elasticity of the eye lens is soon to be reconstructed with the help of femtosecond laser impulses. The short impulses in the areas of a trillionth of a second cut within a thousandth of a millimeter. This surgery could be completed between a 30 second and 1.5 minute duration.

Revolution versus evolution?

A brand-new area is opening up in the field of molecular therapies. Soon it could be possible to turn off certain genes with the help of laser light. Light active pigments concentrate on the hereditary molecule. Subsequently through irradiation with one-colored laser light, selected segments of DNA are inactivated. In stem cell research, laser could take over the function of an injection. Through a microscopic lens, the laser beam hits the external cell membrane and is able to inject a specific substance. However, risks have not been further researched yet.

Despite all of this adulation on its 50-year pathway to success, there is a minor flaw for now: The laser remains a very expensive and complex technology. Compared to other procedures, like for example high-frequency blades, the laser comes with higher investment costs. The laser is and will be not be a medical “panacea.” Being a very flexible tool, laser over the past 50 years has always been a driving force of development, and through optimized technology and advanced functions it will keep on gaining in the future. ”So far we have always destroyed with a laser. At the moment we are learning to regulate functional states of cells with light. In the future, human diseases could thus be eliminated at an early stage,“ states Philipp.

Another solution comes into play to make laser technology more attractive in surgical procedures and reduce high investment costs: “A universal laser, that could be used in many surgical procedures would be ideal. It could be adjusted to fit the purpose of the specific job,“ explains Wehner. “At the moment we are working on being able to use only one instrument for different applications in the future.”

Diana Posth
COMPAMED.de

Translated by Elena O'Meara