LASIK (Laser-Assisted In Situ Keratomileusis) is a widely performed refractive surgery that reshapes the cornea to correct common vision problems like nearsightedness, farsightedness, and astigmatism. While the procedure offers the potential for reduced dependence on glasses or contact lenses, it is not universally suitable. Strict eligibility criteria must be met through a thorough screening process to ensure the procedure’s safety and the likelihood of a successful long-term visual outcome.
Vision Prescription and Stability Requirements
A patient’s refractive error must fall within a treatable range for LASIK to be effective, as the procedure can only remove a limited amount of tissue safely. If the prescription exceeds these parameters, the necessary tissue removal would compromise the structural integrity of the cornea, making the patient ineligible.
The patient’s vision prescription must also demonstrate stability, typically meaning no significant change for at least 12 to 24 months prior to surgery. This stability is crucial because LASIK is a permanent correction of the eye’s current state, and continued fluctuations could quickly negate the surgical benefit, leading to vision regression. Candidates must be at least 18 years old to ensure the eye has reached ocular maturity, although many surgeons prefer to wait until the mid-twenties when the prescription is generally more settled.
Corneal Structure and Integrity Limitations
The physical condition of the cornea is often the most significant factor determining LASIK eligibility because the procedure involves creating a thin flap and then reshaping the underlying tissue. Insufficient corneal thickness is a major contraindication, as a certain amount of tissue must remain after the laser ablation to maintain the eye’s structural strength. If the cornea is too thin for the required correction, the remaining tissue would be too weak and could lead to a serious complication called post-LASIK ectasia, where the cornea bulges outward.
Certain existing corneal diseases also disqualify a patient from LASIK, most notably keratoconus, a progressive condition where the cornea thins and assumes an irregular shape. Since keratoconus already weakens the corneal structure, performing LASIK is contraindicated because it would exacerbate the condition, leading to severe vision distortion. Other conditions, such as severe corneal scarring or recurrent corneal erosion, can also interfere with the surgical process and the quality of the visual outcome.
Systemic and Ocular Health Conditions
A patient’s general health plays a substantial role in healing, which is why certain systemic diseases can prevent LASIK candidacy. Autoimmune disorders like lupus, rheumatoid arthritis, or Sjogren’s syndrome compromise the body’s ability to heal properly, slowing recovery and increasing the risk of infection and scarring after surgery. Uncontrolled diabetes is another risk, as fluctuating blood sugar levels can cause refractive instability and impair wound healing, making the cornea more susceptible to post-operative complications.
Pre-existing ocular conditions not related to the cornea can also be disqualifying factors. Severe dry eye syndrome is a common issue, as the LASIK procedure can temporarily worsen dryness, leading to discomfort and potentially affecting the quality of vision. Conditions affecting the deeper structures of the eye, such as advanced glaucoma or cataracts, require different treatments and may prevent LASIK, as the procedure cannot correct the vision loss caused by these diseases.
Temporary Factors Requiring Deferral
Some factors only require a temporary deferral of the LASIK procedure until the condition resolves or the associated risk passes. Pregnancy and breastfeeding are common temporary contraindications due to hormonal fluctuations that cause vision instability and increase dry eye severity. These hormonal changes can alter the corneal shape and tear film, making accurate pre-operative measurement impossible and increasing the risk of complications.
Certain medications can also necessitate a delay because they interfere with the body’s natural healing process or increase the risk of side effects. For example, isotretinoin, a common acne medication, causes severe dry eye and must be discontinued for a specific period before and after surgery. Active eye infections, such as conjunctivitis or blepharitis, must also be completely treated before a procedure is considered, as surgery on an infected eye significantly elevates the risk of serious post-operative complications.