The Use of Lasers in Surgery

Overview:

The discovery of lasers is considered a prime example of how the analysis of fundamental physics concepts have led to an undoubtedly groundbreaking invention. Due to their versatility, lasers hold use in a broad spectrum of fields, such as in medicine, communications, research, and more. LASER is an acronym which stands for Light Amplification by Stimulated Emission of Radiation.

Lasers are regularly used in medicine for treatment purposes, especially for various surgical procedures. Several operations that use them include laser eye surgery and laser lithotripsy. The thermal energy delivered by the laser burns away unwanted tissue, like plaque in arteries—a waxy substance accumulating on the inner arterial walls that is made of fat, cholesterol, calcium, and other substances in the blood. Additionally, doctors can use lasers, rather than using a scalpel, to cut through tissue. This is advantageous as it allows for cauterization (burning of the flesh around a wound), which seals off blood vessels and therefore limits bleeding.

Laser Eye Surgery (LASIK):

Laser eye surgery is performed in order to change the focal point of where light reaches in one’s eye. Laser-Assisted In Situ Keratomileusis (LASIK) is a prevalent type of laser eye surgery. This procedure is usually done with two lasers. One laser creates a small flap in the cornea (transparent front part of the eye covering the pupil, iris, and the anterior chamber) to expose the pupil (the dark hole located at center of iris), and the other is used to mold the cornea into the correct shape. This process is called photoablation, and it allows the laser to vaporize organic tissue without overheating its surroundings. The flap is then put back over the cornea and left to heal. Since the corneal cells bond very quickly, there is no need for stitches to help the tissue heal.

LASIK is done using a specific laser known as an excimer laser, which transmits concentrated ultraviolet light rays. The procedure also uses a combination of a reactive gas and a noble gas, such as fluorine and chlorine to create a beam used for the photoablation process. Normally, noble gases are not reactive, but as they bond with reactive particles, they become excited and emit ultraviolet radiation. After the excitation, the molecules dissociate and prevent the reabsorption of radiation.

As mentioned before, the objective of laser eye surgery is to change where light reaches the eye. That said, the actual deformations of the eye can be analyzed using the concept of refraction. The cornea and lens (a transparent structure located behind the pupil) work together to focus the light rays that pass through the retina, in order to create clear images of objects that are positioned at various distances. To do this, eyes adjust the lens curvature to change the focal length to focus light properly. A healthy eye will converge light properly by changing the lens shape for the clear visibility of nearby and faraway objects. However, certain conditions result in the incapability of the eye to focus well.

For example, myopia (nearsightedness) is a condition where one’s cornea is excessively curved. This results in a greater refractive index, causing the images to form in front of the retina, where the light converges. This causes nearsightedness, eye strain, and headaches. In a laser-based procedure, a laser can remove small parts of the cornea, producing a flattened cornea with a lower index of refraction than before, enabling images to focus directly on the retina surface and not in front. Another condition, generally referred to as farsightedness, is hypermetropia. In this condition, the cornea is not curved enough, resulting in a lower refractive index, meaning that the images will form behind the retina when the light converges. Some symptoms include headaches, blurry vision when looking at near objects, and eye strain. To adjust this, the laser will remove the corneal outer edge to steepen it. This results in an increased curvature of the cornea, which has a greater refractive index and thus allows images to once again focus directly on the retina. Finally, in astigmatism, light rays entering the eyes don’t focus at a single point, causing disoriented or blurry vision. To treat this, the cornea curvature is evened out, allowing light rays to converge properly.

Lithotripsy Surgery:

Laser lithotripsy surgery is performed to break apart kidney stones that cause blockages in the urinary tract. This procedure aims to fragment them into small pieces using a laser, so they can either be removed manually by the surgeon or exit the body via urination. Unfortunately, kidney stones can get stuck anywhere in the urinary tract, and can completely block the flow of urine. This leads to a buildup of toxins in the body, which can be fatal even in the short-run. They can also be very painful, as they protrude surrounding tissue.

As the laser emits its radiation on the stones, they will absorb the thermal energy transmitted by the laser. The molecules in the stone will then have their bonds broken due to the excessive thermal energy, causing the stone to fragment into smaller pieces. The lasers that are used in these surgical procedures have significantly low wavelengths.

Environmental Impact:

Although lasers are very resourceful devices, they do have some setbacks. Some lasers work at extremely high temperatures and need a lot of water to cool down. This has a negative impact on the environment due to the large amounts of water wasted per annum.

Conclusion:

Overall, the innovative idea of using lasers in surgical procedures has become a frequent practice. It has revolutionized surgical treatment, enabling physicians to operate with maximum precision, convenience, and effectiveness, which has led to more successful surgeries. Even though lasers are disadvantageous in certain ways, they are holistically beneficial for society and undeniably one of the most outstanding treatment options available.

References:

1. Berboucha, M. (2018). This is what happens in laser eye surgery. Forbes. www.forbes.com/sites/meriameberboucha/2018/01/28/this-is-what-happens-in-laser-eye-surgery/#50d09ca449a9.

2. Environment and society. (n.d.). Lasers technologies. lasertechnologies.weebly.com/environment-and-society.html#:~:text=Lasers impact our environment in many ways.&text=Some lasers work at very,for these lasers (Phillips).

3. Laser lithotripsy - an overview. (n.d.). Science direct. www.sciencedirect.com/topics/medicine-and-dentistry/laser-lithotripsy.

4. Winchester Hospital. (n.d.). Laser lithotripsy. www.winchesterhospital.org/health-library/article?id=928068#:~:text=Laser lithotripsy is a procedure,the body in the urine.

5. Uses of lasers in medicine - physics of light. (2016, November 18) Youtube, https://www.youtube.com/watch?v=QWj3NFX71hU.

6. Nucleus Medical Media. (2008). Laser eye surgery (LASIK). Youtube. https://www.youtube.com/watch?v=f-YkzgfgN2k.

7. Laser eye surgery. (n.d.). Weebly. Wsnc2d1lasereyesurgery.weebly.com/role-in-physics.html.

8. TED-Ed. (2019). How does laser eye surgery work? - Dan Reinstein. Youtube. https://www.youtube.com/watch?v=XPDVmBg5DeE.

9. Shiel, W. C. (2018). Definition of excimer laser. MedicineNet. www.medicinenet.com/script/main/art.asp?articlekey=14270.

Footnotes:

1- Ninja, GCSE Physics. “Uses of Lasers in Medicine - Physics of Light.” Youtube, Youtube, November 18, 2016, https://www.youtube.com/watch?v=QWj3NFX71hU.

2- “Role in Physics.” Laser Eye Surgery, snc2d1lasereyesurgery.weebly.com/role-in-physics.html.

3- TED-Ed. “How does laser eye surgery work? - Dan Reinstein.” Youtube, Youtube, November 19, 2019,https://www.youtube.com/watch?v=XPDVmBg5DeE.

4- Nucleus Medical Media. “Laser Eye Surgery (LASIK).” Youtube, Youtube, October 20, 2008, https://www.youtube.com/watch?v=f-YkzgfgN2k.

5- William C. Shiel Jr., MD. “Definition of Excimer Laser.” MedicineNet, MedicineNet, 11 Dec. 2018, www.medicinenet.com/script/main/art.asp?articlekey=14270.

6- Berboucha, Meriame. “This Is What Happens In Laser Eye Surgery.” Forbes, Forbes Magazine, 28 Jan. 2018, www.forbes.com/sites/meriameberboucha/2018/01/28/this-is-what-happens-in-laser-eye-surgery/#50d09ca449a9.

7- “Role in Physics.” Laser Eye Surgery, snc2d1lasereyesurgery.weebly.com/role-in-physics.html.

8- Ibid

9- “Laser Lithotripsy.” Winchester Hospital, www.winchesterhospital.org/health-library/article?id=928068#:~:text=Laser lithotripsy is a procedure,the body in the urine.

10- “Environment and Society.” Lasers, lasertechnologies.weebly.com/environment-and-society.html#:~:text=Lasers impact our environment in many ways.&text=Some lasers work at very,for these lasers (Phillips).