LASIK, or Laser-Assisted In Situ Keratomileusis, is a common elective eye procedure used to correct refractive errors like nearsightedness, farsightedness, and astigmatism. Many people considering this procedure express concern about the level of invasiveness, often asking if a surgeon will use a scalpel to “cut” their eye. The process requires creating a thin, hinged flap on the cornea’s surface to allow the reshaping laser to work underneath. This is accomplished with sophisticated instruments, not a traditional blade, and the term “cutting” does not accurately describe the high-precision technology used.
Clarifying the Corneal Flap
The core of the procedure requires a surgeon to create a corneal flap so they can access the stroma, the thick middle layer of the cornea. This flap is intentionally left attached to the eye by a small hinge, which allows it to be gently lifted and then securely repositioned. The creation of this flap is performed using two primary methods, neither of which involves a conventional surgical knife.
The older, traditional method uses a mechanical microkeratome, an automated system that employs a very fine, oscillating blade to make the precise cut. This high-precision instrument is designed to create a uniform flap thickness across the cornea and has a long history of safety and effectiveness.
A more modern and increasingly common approach is the all-laser, or “bladeless,” technique, which utilizes a femtosecond laser. This infrared laser delivers ultra-short pulses of energy to a specific, predetermined depth within the cornea, creating microscopic bubbles of gas and water that form the plane of separation for the flap. The femtosecond laser allows the surgeon to customize the flap’s thickness, diameter, and edge angles with exceptional precision.
The Corrective Phase
Once the corneal flap is created and gently folded back, the underlying stromal tissue is exposed for the second part of the procedure. This is the corrective phase, which involves the use of an excimer laser. This laser is a computer-controlled system that emits cool, ultraviolet light to precisely remove, or ablate, microscopic amounts of tissue.
The excimer laser reshapes the curvature of the cornea according to a specific, programmed map of the patient’s eye. For example, to correct nearsightedness, the center of the cornea is flattened, while farsightedness requires the center to be made steeper. The laser removes tissue with incredible accuracy, often in increments as small as 0.25 microns, which is far thinner than a human hair. After the excimer laser finishes the ablation, the surgeon carefully repositions the corneal flap back into its original place. The flap adheres naturally without the need for stitches, acting as a kind of organic bandage over the newly reshaped tissue.
Pre-Procedure Screening and Safety Technology
The safety and success of the procedure rely heavily on a comprehensive pre-operative screening process that determines patient suitability. This initial evaluation includes specialized tests to ensure the eye is structurally sound and to gather precise data for the laser treatment.
Pachymetry
This initial evaluation includes specialized tests such as pachymetry, which measures the cornea’s thickness. This ensures there is enough residual tissue left after the correction to maintain the eye’s structural stability, as a minimum safe thickness is a requirement for candidacy.
Corneal Topography
Another fundamental test is corneal topography, which uses light to create a detailed, three-dimensional map of the corneal surface and curvature. This map identifies irregularities, such as early signs of keratoconus, and provides the precise data needed to program the excimer laser for a customized correction.
Eye-Tracking Technology
Safety during the procedure is significantly enhanced by advanced eye-tracking technology, often called a gaze tracker. Even if the patient is focused on a target light, involuntary eye movements can occur, but this system automatically follows the slightest shifts in the eye’s position. If the eye moves outside of a safe treatment zone, the laser immediately pauses and only resumes when the eye is properly realigned. This ensures that the laser pulses are delivered with accuracy to the intended location.
Immediate Recovery and Short-Term Healing
Immediately following the procedure, patients commonly report sensations of grittiness, watering, or a mild burning feeling, which typically subside within the first few hours. Vision is often blurry or hazy right after the procedure, but a significant improvement in visual clarity is one of the hallmarks of the immediate recovery period. Most patients experience functional vision within the first 24 to 48 hours.
Patients are given protective eye shields to wear, particularly while sleeping, to prevent accidental rubbing or pressure on the eye during the initial healing phase. Prescribed antibiotic and anti-inflammatory eye drops are used for about a week to promote proper healing and reduce the risk of infection. The corneal flap serves as a natural barrier and adheres quickly, but patients must avoid activities like swimming for at least one to two weeks to prevent contamination or dislocation of the flap.
While a vast majority of healing occurs rapidly within the first day, full stabilization of vision can take longer. Minor fluctuations in vision and temporary dry eye symptoms are common in the weeks following the procedure. Most individuals are cleared to resume work and driving within one to two days, with complete healing and final visual results typically stabilizing over the course of three to six months.