LASIK (Laser-Assisted In Situ Keratomileusis) is a common surgical procedure that reshapes the cornea to correct refractive errors and reduce the need for glasses or contact lenses. Eligibility is not solely determined by age, as the procedure requires candidates to meet specific physiological and health criteria. The decision to proceed involves a thorough evaluation to ensure the procedure is safe and effective long-term.
The Critical Role of Age and Prescription Stability
A person who is 20 years old meets the minimum age requirement for LASIK, which the U.S. Food and Drug Administration (FDA) has approved for individuals 18 years and older. However, most surgeons prefer patients to be in their early to mid-twenties, when vision is more likely to be stable. The eye can continue to grow and change throughout the late teens and early twenties, especially in cases of myopia (nearsightedness).
The most important factor is prescription stability, meaning the refractive error has not changed significantly for 12 to 24 months. A significant change is defined as a variation greater than 0.5 diopters in corrective lens power. Performing LASIK on an unstable prescription is counterproductive because the eyes may continue to change after surgery, potentially requiring glasses or contact lenses again. If the eyes are still maturing, the correction may not be permanent, leading to the need for an enhancement procedure later.
Essential Eye Health and Anatomy Requirements
Age and stability are only the first hurdles; the physical structure and health of the eye must also be appropriate for corneal reshaping. The cornea, the transparent front surface of the eye, must have sufficient thickness because LASIK removes a small amount of tissue to alter its curvature. While the average cornea is 540 to 560 micrometers thick, surgeons typically prefer a minimum of 500 micrometers for the procedure.
A layer of untouched stromal tissue, known as the residual stromal bed, must remain after laser ablation to maintain the cornea’s structural integrity and prevent complications like corneal bulging. This safety margin often disqualifies candidates with thinner corneas.
Contraindications
Pre-existing eye conditions can prevent eligibility, including severe dry eye syndrome, which the procedure can aggravate, or uncontrolled glaucoma. Systemic health issues are also contraindications because they can impair healing after surgery. These include uncontrolled diabetes and autoimmune disorders such as lupus or rheumatoid arthritis. Women who are pregnant or nursing are advised to postpone LASIK because hormonal changes can temporarily affect vision and prescription accuracy.
The Pre-Operative Consultation Process
LASIK eligibility is definitively determined through a comprehensive pre-operative consultation with an eye surgeon. This appointment involves a series of advanced diagnostic tests that measure the eye’s specific anatomical features.
Diagnostic Tests
- Corneal topography creates a detailed three-dimensional map of the corneal surface, identifying irregularities in its shape.
- Pachymetry precisely measures corneal thickness, allowing the surgeon to calculate the amount of tissue that can be safely removed.
- Eye dilation is performed to examine the retina and internal structures for underlying health issues.
To ensure the accuracy of these measurements, contact lens wearers must temporarily stop wearing their lenses prior to the appointment. This “contact lens holiday” is necessary because lenses can temporarily alter the shape of the cornea, leading to inaccurate readings. The duration of this break varies, typically lasting several days to a few weeks, depending on the type of lenses worn.
Options When LASIK Eligibility Is Not Met
When a person fails to meet the criteria for LASIK, several other effective vision correction procedures are available.
Photorefractive Keratectomy (PRK)
PRK is a laser procedure similar to LASIK but does not require the creation of a corneal flap. This makes PRK a viable alternative for people with corneas that are too thin for LASIK or for those whose lifestyle involves a high risk of eye trauma, such as athletes.
Implantable Collamer Lens (ICL)
The ICL involves surgically placing a corrective lens inside the eye, either in front of or behind the iris. ICLs are often recommended for individuals with very high prescriptions or thin corneas, as this procedure does not alter the corneal tissue. Unlike laser procedures, ICLs are reversible, meaning the implanted lens can be removed or replaced if necessary.