The Accident That Led to Modern-Day Laser Corrective Eye Surgeries

By Roshni Printer

 

 

It is fascinating to note that some of the most groundbreaking scientific discoveries happened by chance. Awarded a Golden Goose Award in 2022, one such “accident” in the medical field led to the invention of “bladeless laser-assisted in situ keratomileusis,” a laser corrective eye surgery commonly known as bladeless LASIK.

What is LASIK?

LASIK is a procedure in which a laser is used to reshape the cornea to treat a range of vision problems, such as myopia (near-sightedness), hyperopia (far-sightedness) and astigmatism [1]. Myopia is a condition where individuals struggle to see distant objects, due to an excessive length of the eyeball or excessive curvature of the lens, leading to the formation of image in front of the retina. In contrast, hyperopia allows individuals to see distant objects but not close objects, due to the short length of the eyeball or insufficient curvature of the lens, so the image forms behind the retina. Another common type of refractive error, astigmatism, is caused by the irregular shape of the cornea or lens. In these conditions, images cannot be sharply focused on the retina, leading to blurry vision. Through a corrective eye surgery, the shape of the cornea can be altered by precisely cutting off some part of the deeper cornea (corneal stroma), so that light can be correctly refracted onto the retina.

 

From a technical point of view, the upper layers of cornea have to be removed before reshaping the stroma. This required a mechanical blade – until a seemingly unrelated lab accident happened [2, 3].

From a Lab Accident to a Successful Startup

Back in 1985, physicists Gérard Mourou and Donna Strickland invented a groundbreaking optical technique called “chirped pulse amplification,” which can produce ultrashort laser pulses as short as a femtosecond (10-15 second) with an intensity higher than ever [4]. Mourou later founded the Center for Ultrafast Optical Science at the University of Michigan, and took advantage of this technique to understand chemical reactions [3].

 

In 1993, one of Mourou’s graduate students working in the center sustained an accidental laser injury to his eye during an experiment [3]. Recalled that he “must have been tired” that evening, Detao Du accidentally lifted his safety goggles, and a stray beam (fortunately not the main beam) of the femtosecond laser produced circular burns to the his retina. Upon examination by Ron Kurtz, a doctor on duty at the University’s eye center, the burns were found to be perfectly circular and precise without damaging any surrounding tissue. Du and Kurtz were both fascinated by the perfect nature of the laser cut, so they decided to collaborate and investigate further.

 

In an optics conference where Du and Kurtz presented their findings, the duo met Tibor Juhasz, a previous member of Mourou’s lab, who was seeking femtosecond laser applications in ophthalmology. This was where the development of bladeless LASIK began. Together they founded a successful startup to commercialize bladeless LASIK, and the company was acquired a decade later for US$808 million in 2007. Notably, Mourou and Strickland were awarded a Nobel Prize in Physics “for their method of generating high-intensity, ultrashort optical pulses” in 2018.

LASIK vs SMILE

Bladeless LASIK is a well-established option considered to be effective with more than 95% of patients satisfied with the outcome of the surgery [1]. In the surgery, a femtosecond laser is used to create a thin, circular flap of the upper layers of cornea, after which the underlying stromal tissue is reshaped using an excimer laser [5]. The ultraviolet energy (greatly amplified ultraviolet light) emitted by the excimer laser functions to break the organic molecular bonds in the stromal tissue without causing any thermal damage [6]. After precisely removing the stromal tissue, the corneal flap is flipped back to its original position and the cornea is allowed to heal naturally.

 

Recently, a novel refractive surgery procedure known as “small incision lenticule extraction” (SMILE) has also gained popularity since its introduction in 2016 [7]. This minimally invasive procedure adjusts the refractive power of the cornea by carving out a lenticule from the corneal stroma with a femtosecond laser, followed by the extraction of the lenticule through a small incision also made by a femtosecond laser [8].

 

Primary advantages of SMILE come from its small incision size. LASIK requires cutting a 270 degree, 20 mm circular flap [7], while SMILE involves only a 2–4 mm incision [7, 9]. This greatly reduces the transection of corneal nerves, and hence lessens the experience of dry eyes after the surgery [8]. SMILE also suits contact sport players (e.g. soccer and martial arts) more because it does not involved a corneal flap which may move in some unlikely cases [8, 10]. Additionally, SMILE was also found to be more stable in high myopia [8].

 

For the downside, LASIK allows touch-ups to fine-tune vision after some years, but this is not possible for SMILE [7]. If an enhancement procedure is needed for an eye treated by SMILE, the options are to perform LASIK or an older PRK technique (footnote 1) on the SMILE cap. In addition, SMILE has not been approved to treat hyperopia in the US, so LASIK remains the only choice for people with far-sightedness at the moment [8].

 

While both procedures demonstrate efficacy and safety, the choice between SMILE and LASIK ultimately depends on individual patients and specific eye conditions. Please seek medical advice from your eye doctor if you are considering one of these corrective eye surgeries.

Summary

While what happened to be an accidental discovery turned into one of the most sought-after medical procedures in modern-day ophthalmology, many researchers, including Kurtz and Juhasz, continue to explore novel applications of the femtosecond laser for eye diseases such as glaucoma and cataract [3]. This story shows the impact of chance on scientific progress, standing testament to the fact that life-changing discoveries can occur any time of the day – so keep an eye out!

  1. PRK: Photorefractive keratectomy (PRK) is an older technique which requires scraping off the upper layers of cornea (instead of creating a flap which will be flipped back to its original position). The tissue will then be allowed to regrow, but the healing process can take several weeks [11].

References

[1] Kates, M. M., & Tuli, S. (2020). What Is LASIK Eye Surgery?. JAMA, 324(8), 815. https://doi.org/10.1001/jama.2020.1286

[2] Barraquer, J. I. (1996). The History and Evolution of Keratomileusis. International Ophthalmology Clinics, 36(4), 1–7. https://doi.org/10.1097/00004397-199603640-00003

[3] Asbury, M. (n.d.). How a Lab Incident Led to Better Eye Surgery for Millions of People. The Golden Goose Award. https://www.goldengooseaward.org/01awardees/lasik

[4] Rose, J. (n.d.). The Nobel Prize in Physics 2018 - Popular science background: Tools made of light. The Nobel Prize. https://www.nobelprize.org/prizes/physics/2018/popular-information/

[5] Department of Ophthalmology, Hong Kong Sanatorium & Hospital. (n.d.). Laser-assisted In-situ Keratomileusis (LASIK). https://www.hksh-hospital.com/oph/en/our-services/lasik.php

[6] Trokel, S. L., Srinivasan, R., & Braren, B. (1983). Excimer Laser Surgery of the Cornea. American Journal of Ophthalmology, 96(6), 710–715. https://doi.org/10.1016/s0002-9394(14)71911-7

[7] Stephenson, M. (2021, April 15). The Current State of SMILE vs. LASIK. Review of Ophthalmology. https://www.reviewofophthalmology.com/article/the-current-state-of-smile-vs-lasik

[8] Shah, R. (2019). History and Results; Indications and Contraindications of SMILE Compared With LASIK. Asia-Pacific Journal of Ophthalmology, 8(5), 371–376. https://doi.org/10.1097/01.APO.0000580132.98159.fa

[9] Moshirfar, M., Somani, S. N., & Patel, B. C. (2024, February 26). Small Incision Lenticule Extraction. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK549896/

[10] Cleveland Clinic. (2024, February 5). LASIK vs. SMILE: Which Is Right for You? https://health.clevelandclinic.org/lasik-vs-smile

[11] Oliver, B. (2024, January 31). LASIK vs. PRK: Which Laser Eye Surgery Is Right for You? John F. Hardesty, MD, Department of Ophthalmology & Visual Sciences. https://ophthalmology.wustl.edu/lasik-vs-prk-which-laser-eye-surgery-is-right-for-you/