LASIK is highly successful, but vision changes can occur over time due to natural aging or a slight regression of the initial correction. Patients often wonder if they can have the procedure again to restore clear vision. The answer is frequently yes, through a secondary procedure known as a LASIK “enhancement” or “retreatment.” This touch-up is a common and predictable part of modern laser vision correction. The need for an enhancement is usually a result of the eye’s natural healing process or changes over many years, not a failure of the original surgery. Eligibility is determined by a comprehensive evaluation of the eye’s current health and structure.
Assessing Corneal Health and Stability
The primary factor determining eligibility for a second LASIK procedure is the remaining thickness of the cornea. During the original surgery, a thin flap is created and tissue is removed from the underlying corneal bed, or stroma, to correct the refractive error. Since a second treatment removes more tissue, the residual corneal bed thickness becomes the main limiting factor.
Surgeons measure the cornea to ensure that a minimum of 250 to 300 micrometers of tissue remains in the posterior stroma after the enhancement. This requirement is a safety measure to maintain the cornea’s structural integrity. It prevents ectasia, a rare but serious complication where the cornea weakens and bulges forward. A thorough pre-operative mapping, called corneal topography, is essential to analyze the cornea’s shape and thickness distribution.
The stability of the refractive error is another critical requirement. Before proceeding with an enhancement, the prescription must have remained stable for a specific period, typically 6 to 12 months, to ensure the new correction is lasting. If the vision change is still actively progressing, the surgeon will likely recommend waiting or investigating other causes. Progressive vision change could signal an underlying condition that must be addressed before any laser treatment.
Overall eye health is also carefully assessed to rule out new conditions that may be causing the vision change, such as the early formation of cataracts. If the cornea is too thin to safely undergo a LASIK flap-lift and further tissue removal, the surgeon may recommend an alternative procedure. This alternative is often Photorefractive Keratectomy (PRK), which corrects vision on the surface of the eye without requiring the pre-existing flap to be lifted.
How a LASIK Enhancement is Performed
The procedure for a LASIK enhancement is similar to the original surgery, but the flap does not need to be created again. The surgeon uses a specialized, blunt instrument to gently separate and lift the original corneal flap, which remains loosely adhered to the stroma. This process typically takes only a few minutes and is less invasive than creating a new flap.
Once the flap is lifted and folded back, the excimer laser is applied to the exposed corneal bed to perform the small amount of tissue ablation needed to correct the residual error. Since enhancements usually address only minor prescription changes, the laser treatment time is often shorter than the initial surgery. After the laser sculpts the cornea, the flap is carefully repositioned back into place.
The flap naturally adheres quickly without the need for stitches, acting as a natural bandage over the treated area. In rare instances where the original flap cannot be safely lifted, the surgeon may choose to perform PRK directly on the flap’s surface. Recovery following an enhancement is generally faster than the initial LASIK procedure because the deeper structures of the cornea are already stable.
Potential Complications of Repeat Procedures
While highly effective, a second LASIK procedure carries a different profile of potential complications compared to the first surgery. The primary risks relate to the manipulation of the pre-existing corneal flap. Re-lifting the flap increases the chance of epithelial ingrowth, where surface cells migrate and grow underneath the flap interface, causing visual disturbances that may require a second procedure to resolve.
Flap-related issues like microstriae, which are microscopic wrinkles in the flap, can occur upon repositioning, potentially leading to slight visual blurring. Another common concern is the increased risk of severe dry eye post-enhancement. Since the initial surgery already affected the corneal nerves, a second procedure can further disrupt tear production and nerve function. Aggressive dry eye management is often needed following retreatment.
The most serious, though rare, complication is the further increase in the risk of corneal ectasia. This risk is primarily mitigated by rigorous pre-operative screening, which must confirm a safe amount of tissue remains. Selecting a surgeon with extensive experience in performing these delicate retreatment procedures is highly advisable due to the unique challenges of working with a previously altered cornea.