LASIK surgery, which stands for Laser-Assisted In Situ Keratomileusis, is a common elective surgical procedure performed globally. This vision correction technique reshapes the cornea, the clear front surface of the eye, to correct refractive errors such as nearsightedness, farsightedness, and astigmatism. Modern LASIK relies on sophisticated laser technology to achieve its precision. Understanding the different laser systems involved is the first step toward appreciating how your surgeon selects the best approach for your individual vision needs. The technology used in the procedure is divided into two distinct parts, each requiring a specialized laser system.
The Flap Creation Laser (Femtosecond Technology)
The initial step in a LASIK procedure is creating a thin, hinged flap on the cornea’s surface. Historically, this was done using a mechanical instrument called a microkeratome. Today, the gold standard is all-laser LASIK, where a femtosecond laser performs this task without a blade. This laser emits ultra-fast pulses of light, measured in femtoseconds, to create microscopic bubbles within the corneal tissue.
The precise placement of these bubbles separates the tissue layer at a programmed depth, forming the corneal flap with a predictable thickness. Major platforms, such as the IntraLase/iFS, Alcon FS200, and the Ziemer Femto LDV, all use this technology. Newer femtosecond lasers operate at higher speeds, allowing for quicker flap creation and potentially smoother stromal beds than earlier generations. This precision allows the surgeon to customize the flap’s diameter, thickness, and the angle of the side-cut, which aids in better flap alignment after the procedure.
The Vision Correction Laser (Excimer Technology and Customization)
Once the corneal flap is gently lifted, the second laser, known as the excimer laser, is used to reshape the underlying tissue. This laser uses cool, ultraviolet light to remove or “ablate” microscopic amounts of corneal tissue, correcting the refractive error. For example, the excimer laser gently flattens the cornea to treat nearsightedness or steepens it to correct farsightedness. The amount and pattern of tissue removed are unique to each patient and are controlled by computer settings programmed with the patient’s prescription.
A key differentiator among excimer laser platforms is the level of customization they offer for this reshaping process. Standard treatments correct only the basic prescription, but modern systems utilize advanced mapping to address subtle imperfections in the eye’s optical system, known as higher-order aberrations.
Wavefront-guided systems, such as those used by VISX lasers, create a detailed map of the eye’s entire optical pathway, similar to a fingerprint, and guide the laser ablation based on this data. Wavefront-optimized treatments, like those found on the Alcon WaveLight EX500, focus on preserving the natural curvature of the cornea, which can reduce spherical aberration and improve night vision quality. The most advanced customization is achieved with topography-guided treatments, such as Contoura Vision, which map over 22,000 points on the corneal surface itself. This extensive mapping allows the laser to smooth out irregularities on the cornea, which can be beneficial for patients with subtle corneal distortions or previous refractive surgery. All FDA-approved excimer lasers are proven to be safe and effective, but their specific customization features provide different approaches to achieving optimal vision.
Key Metrics for Comparing Laser System Performance
Beyond the brand name or the type of customization, several technical specifications dictate a laser system’s performance and contribute to the final outcome. A primary metric is the high-speed, multi-dimensional eye tracking system integrated into the excimer laser. Since even a small eye movement could affect accuracy, these trackers monitor the eye’s position in real time, ensuring the laser pulse is delivered to the precise, intended location. The best trackers compensate for movements in multiple planes, including horizontal, vertical, and rotational shifts.
Another performance metric is the ablation speed or repetition rate of the excimer laser, often measured in hertz. Faster lasers, such as those operating at 500 Hz, complete the reshaping portion of the procedure in mere seconds. This reduced treatment time minimizes the period the corneal tissue is exposed, which reduces the risk of dehydration and improves predictability.
The size and profile of the laser spot are also significant technical details. A smaller spot size, often less than one millimeter, allows the laser to sculpt the cornea with greater detail and smoothness. An optimized beam profile ensures that the energy delivered across the treatment area is uniform, which is crucial for achieving a smooth corneal surface and minimizing irregularities.
Why There Is No Single Best Laser System
There is no single best LASIK laser system because there is no single best machine for every patient. All modern, FDA-approved laser platforms are capable of producing excellent results and have comparable safety and efficacy profiles. Differences in technology often mean one platform may be better suited for a particular eye characteristic than another.
The “best” choice is ultimately determined by a combination of factors specific to the patient and the provider. This includes the unique characteristics of the patient’s eye, such as the severity of the prescription, corneal thickness, and pupil size, which may favor one system’s customization capabilities. More important than the specific brand of equipment is the diagnostic workup performed before the surgery, which generates the data used to program the laser. The surgeon’s experience, skill, and familiarity with a particular laser platform remain the most influential factors in achieving a successful visual outcome.