Laser-Assisted In Situ Keratomileusis, or LASIK, is a widely performed elective surgical procedure that uses a laser to reshape the cornea. This procedure corrects common vision problems like nearsightedness, farsightedness, and astigmatism, offering a path to reducing dependence on glasses or contact lenses. Determining eligibility involves a comprehensive eye examination, but a primary factor is the patient’s age. The age requirement is tied directly to the physical maturity of the eye and the long-term effectiveness of the correction.
The Minimum Age Requirement
The minimum age requirement for LASIK is standardized at 18 years old across the United States and many other countries. This guideline is set by the Food and Drug Administration (FDA) and adopted by medical professionals, as 18 is considered the age of sufficient physical and ocular maturity. However, 18 is only a starting point for candidacy, not a guarantee of approval. Many surgeons advise patients to wait until their early twenties because the eye’s refractive power often continues to change past the age of 18.
The Critical Factor: Refractive Stability
The true determinant for LASIK eligibility is not chronological age but the stability of the vision prescription, known as refractive stability. Performing the procedure before the eye’s structure has settled can render the surgical correction temporary, as the prescription may continue to change afterward, leading to a return of poor vision.
Refractive stability is defined as having a prescription that has not changed significantly for a specific period, typically 12 to 24 months. A change of less than 0.50 diopters—the unit used to measure lens power—between annual eye exams is often considered stable enough for treatment. This waiting period ensures that the eyes have completed the growth and development that frequently cause vision changes during adolescence. The eye’s axial length often continues to lengthen throughout the teenage years, contributing to worsening nearsightedness. By waiting for stability, the surgeon ensures the laser corrects a permanent refractive error, maximizing the long-term success of the procedure.
Other Key Eligibility Criteria
Corneal Health and Thickness
A comprehensive evaluation of overall eye health is necessary for candidacy. One important physical criterion is the health and thickness of the cornea, the transparent front surface of the eye that the laser reshapes. The average cornea is approximately 520 to 555 microns thick. During LASIK, a thin flap is created, and underlying corneal tissue is removed. Surgeons must ensure that a minimum amount of tissue, called the residual stromal bed, remains intact after the laser ablation to maintain the eye’s structural integrity. This remaining bed must typically measure at least 250 to 270 microns to prevent corneal ectasia, a complication where the cornea weakens and bulges forward.
Disqualifying Health Conditions
Beyond corneal thickness, a patient’s general eye health can be a disqualifying factor. Active eye infections or inflammation must be fully resolved before surgery. Certain systemic health conditions, particularly autoimmune diseases, may also disqualify a candidate due to the potential for impaired healing. Disqualifying conditions include:
- Severe dry eye disease.
- Uncontrolled glaucoma.
- The presence of cataracts.
- Autoimmune diseases like rheumatoid arthritis or Sjögren’s syndrome.
Prescription Limits
Finally, the patient’s prescription must fall within the treatable range of the laser technology. While advanced lasers can correct a wide spectrum of errors, there are limits. These limits are generally around -12.00 diopters for nearsightedness, +6.00 diopters for farsightedness, and ±6.00 diopters for astigmatism.