LASIK (Laser-Assisted In Situ Keratomileusis) is a widely performed surgical procedure that corrects refractive errors, often reducing or eliminating the need for glasses and contact lenses. Strict eligibility criteria must be met to ensure the long-term safety and success of the surgical outcome. Determining candidacy involves a detailed assessment of a person’s vision stability, the physical health of the eyes, and their overall systemic health profile.
Vision and Prescription Requirements
A fundamental requirement for LASIK is that a patient must be at least 18 years old. The emphasis is less on the minimum age itself and more on the necessary stability of the vision correction prescription. Surgeons generally require the prescription to have remained unchanged for a period of at least one to two consecutive years to ensure the correction will be lasting and prevent a regression of vision post-surgery.
LASIK is designed to treat three main refractive errors: myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. The procedure is typically effective for myopia up to -12.00 diopters (D), hyperopia up to +6.00 D, and astigmatism up to 6.00 D. Prescriptions that fall outside of these established limits may not be safely or predictably corrected because higher corrections require the removal of more corneal tissue. The need to remove excessive tissue can compromise the structural integrity of the cornea.
Ocular Health Prerequisites
The physical structure and health of the eye are thoroughly examined to confirm suitability for the procedure. Adequate corneal thickness is a major determining factor because LASIK involves creating a thin flap and reshaping the underlying corneal tissue with a laser. Most surgeons prefer a minimum thickness of 500 micrometers (µm) for LASIK.
The tissue remaining in the central cornea after the flap is created and the laser correction is applied, known as the residual stromal bed, must maintain a thickness of at least 250 µm to 300 µm to prevent a serious complication called corneal ectasia. Certain pre-existing eye diseases can also be disqualifiers, including keratoconus (a progressive thinning and outward bulging of the cornea) and uncontrolled glaucoma. Severe dry eye syndrome is another common exclusion because the LASIK procedure itself can temporarily worsen tear film instability, hindering proper healing. Pupil size is also evaluated, as patients with naturally large pupils, particularly in low-light conditions, may experience increased glare and halos post-surgery.
General Health and Medical Exclusions
A patient’s overall systemic health plays a significant part in the healing process following LASIK. Certain systemic conditions are considered contraindications because they can impair the body’s ability to heal or increase the risk of complications. Active autoimmune disorders, such as Lupus or Rheumatoid Arthritis, disqualify a candidate because these conditions interfere with the predictable wound-healing response of the eye.
Uncontrolled diabetes presents a risk because fluctuating blood sugar levels can cause temporary vision changes and impede the body’s natural healing mechanisms. Hormonal changes related to life stages like pregnancy and nursing are temporary contraindications. These periods can cause temporary shifts in vision stability and prescription, requiring the procedure to be postponed until hormones return to normal. Certain medications, including the acne medication isotretinoin, increase dry eye severity and impair corneal healing, meaning patients must stop taking them for a specified period before surgery.
The Candidacy Evaluation Process
Meeting the general eligibility criteria is merely the first step toward approval for LASIK. The process culminates in a comprehensive, in-person evaluation conducted by the surgeon’s team. This detailed assessment moves beyond a standard eye examination to gather highly specific data about the eye’s anatomy and function.
Advanced diagnostic tools measure the eye’s unique characteristics. Corneal topography creates a precise, three-dimensional map of the corneal surface curvature, essential for planning the laser treatment. Pachymetry measures the exact thickness of the cornea, confirming sufficient tissue for a safe procedure. Wave-front analysis assesses subtle vision imperfections that a standard prescription cannot measure, allowing for a highly customized treatment plan. Full disclosure of all medical history, medications, and health conditions is mandatory to ensure the surgeon can confirm safety and predict a successful outcome.