Photorefractive Keratectomy (PRK) is a type of laser eye surgery designed to correct common refractive errors such as myopia, hyperopia, and astigmatism. This procedure uses an excimer laser to reshape the cornea, the transparent front surface of the eye. By altering the cornea’s curvature, PRK changes how light is focused onto the retina, aiming to reduce or eliminate a patient’s dependence on glasses or contact lenses. PRK was a foundational breakthrough that set the stage for all modern laser vision correction techniques.
The Necessary Scientific Precursors
The path to PRK began in industrial research laboratories focused on materials science. A significant discovery occurred in 1981 when physicist Rangaswamy Srinivasan, working at IBM, determined that the excimer laser could precisely etch organic polymers. This ultraviolet laser emitted high-energy pulses capable of ablating microscopic layers of material without causing thermal damage to the surrounding tissue. This effect, termed “ablative photo-decomposition,” was unlike previous laser technology, which typically burned or melted tissue.
This finding was quickly recognized for its potential in medicine, especially for the delicate structures of the human eye. Ophthalmologists like Dr. Stephen Trokel began experimenting with the excimer laser in the early 1980s, working on cadaver eyes. Their research confirmed that the laser could remove corneal tissue with extraordinary control and precision. This established the core scientific principle that a laser could safely sculpt the cornea to correct a refractive error.
The First Successful Human Application
The conceptual groundwork for PRK was established in 1983 when Dr. Trokel and his colleagues published a landmark paper outlining the idea of using the excimer laser to sculpt the cornea. The first actual surgical application on a human eye occurred a few years later, marking the shift from experimental theory to clinical reality around 1987 and 1988.
In 1987, Dr. Theo Seiler in Berlin, Germany, performed one of the earliest PRK procedures. Around the same time, Dr. Marguerite McDonald performed the first PRK procedure on a sighted human eye in early 1988, providing important data on safety and effectiveness. These initial operations confirmed the excimer laser’s ability to precisely reshape the corneal surface to correct myopia, demonstrating that PRK was a viable technique for vision correction.
The Global Path to Clinical Acceptance
Following the initial procedures, the late 1980s and early 1990s involved extensive multicenter clinical trials to validate PRK’s safety and long-term results. These trials were essential for moving the procedure to a widely accepted treatment for refractive errors. Data collected demonstrated that PRK provided stable and predictable outcomes, particularly for low-to-moderate degrees of nearsightedness.
The process of gaining regulatory approval varied by region. Canada was among the first countries to approve the excimer laser for PRK treatments in 1991. In the United States, the procedure underwent rigorous review by the Food and Drug Administration (FDA) before receiving formal approval in 1995 for the treatment of myopia. This 1995 approval solidified PRK’s status as the first successful laser vision correction procedure available to the general public in the US.
The formal approval by major regulatory bodies signaled the global acceptance of PRK as a standard surgical option. While LASIK later surpassed PRK in popularity, PRK remains a preferred option for patients with thinner corneas or other factors that make them unsuitable for a LASIK flap. Its widespread clinical adoption cemented its legacy as the procedure that launched the era of modern laser refractive surgery.