LASIK surgery is one of the most transformative procedures in all of ophthalmology. The ability to wake up and see clearly — without reaching for glasses or fumbling with contact lenses — changes daily life in ways patients consistently describe as far exceeding their expectations.
But LASIK is not suitable for everyone, and a responsible surgeon will not recommend it unless the candidacy criteria are genuinely met. In my experience, about 70–75% of patients who come in hoping for LASIK are good candidates. The rest require either a different procedure or further observation before proceeding.
Here is everything you need to understand before booking a LASIK evaluation.
How LASIK Actually Works
LASIK (Laser-Assisted In Situ Keratomileusis) uses an excimer laser to precisely reshape the cornea — the transparent dome at the front of the eye. By changing the cornea's curvature, we alter how light focuses on the retina, correcting myopia, hyperopia, and astigmatism.
The procedure has two steps: a thin flap is created on the corneal surface (using either a microkeratome blade or, preferably, a femtosecond laser for blade-free LASIK), the flap is lifted, the excimer laser reshapes the underlying corneal tissue, and the flap is repositioned. The entire procedure for both eyes takes approximately 15–20 minutes. There is no stitching — the flap heals naturally.
Are You a Good Candidate? The 6 Key Criteria
Age: 18 years minimum, ideally 21+
The prescription must be stable for at least 12 months before surgery. Younger patients often have prescriptions that are still changing. We generally prefer to wait until 21 years of age, when myopia has typically stabilised, unless stability is clearly documented over 2 or more years.
Prescription within treatable range
LASIK effectively treats myopia up to approximately -10.00 D, hyperopia up to +4.00 D, and astigmatism up to 5.00 D. Higher prescriptions beyond these limits may be better treated with implantable lens procedures (ICL) rather than LASIK.
Adequate corneal thickness
LASIK removes corneal tissue to reshape it. You must have sufficient corneal thickness to allow safe removal while maintaining structural integrity. This is measured by corneal topography and pachymetry (thickness mapping) and is one of the most common reasons patients are found unsuitable for LASIK — though they may be candidates for other laser procedures like PRK/LASEK or ICL.
Normal corneal shape (no keratoconus)
Keratoconus is a condition where the cornea gradually thins and bulges. It is an absolute contraindication to LASIK — performing the procedure would dangerously weaken an already compromised cornea. We screen for this rigorously with corneal topography. Even subtle ("forme fruste") keratoconus is a disqualifier.
No significant dry eye
LASIK can temporarily worsen dry eye symptoms, as the procedure affects the corneal nerves that regulate tear production. Patients with pre-existing significant dry eye disease require careful evaluation and may need treatment before surgery, or may be better suited to surface laser ablation (PRK) which has a less severe effect on corneal nerves.
No disqualifying systemic conditions
Certain conditions — including uncontrolled autoimmune diseases, active infections, pregnancy, and breastfeeding — require deferral of surgery. Diabetes, if well-controlled, is usually not a contraindication but requires careful assessment. Each patient's full medical history is reviewed before any recommendation is made.
Patients who are not LASIK candidates are not without options. PRK/LASEK is suitable for thinner corneas. ICL (Implantable Collamer Lens) corrects very high prescriptions without removing corneal tissue. Refractive lens exchange is ideal for patients over 45 with presbyopia. We will always find the right solution.
What the Pre-Surgical Evaluation Involves
At The Eye Clinic, a LASIK candidacy evaluation is a thorough 60–90 minute appointment that includes:
- Uncorrected and best-corrected visual acuity
- Manifest and cycloplegic refraction — the accurate spectacle prescription
- Corneal topography — a detailed map of the corneal curvature to detect any irregularity or keratoconus
- Corneal pachymetry — thickness measurement at multiple points across the cornea
- Tear film and dry eye assessment
- Pupil size measurement in dim light — large pupils in dark conditions can affect outcomes at night
- Dilated fundus examination — to ensure the retina is healthy before proceeding
You will be asked to stop wearing contact lenses before this evaluation — soft lenses for at least 1 week, and rigid or toric lenses for 3–4 weeks, as they temporarily alter corneal shape.
Remove soft contact lenses at least 7 days before your appointment. Remove hard/rigid lenses at least 3–4 weeks before. Bring your current glasses. You will not be able to drive yourself home after the evaluation as your pupils will be dilated.
What Results Can You Realistically Expect?
In appropriate candidates, LASIK delivers excellent outcomes. Studies consistently show:
- Over 95% of patients achieve 6/12 or better uncorrected vision (adequate for driving)
- Over 85% achieve 6/6 (perfect unaided vision) after the procedure
- High patient satisfaction rates — consistently among the highest of any elective surgical procedure
Most patients notice dramatically improved vision within 24 hours. Final, stable vision is typically achieved within 1–3 months as the eye heals and the cornea settles.
"LASIK doesn't just correct vision — it gives patients back the freedom to swim, play sport, travel, and wake up seeing the world without reaching for glasses."
— Dr. Swati Agarwal, Gold Medalist Eye SurgeonA Note on Age and Reading Vision
LASIK corrects distance vision but does not prevent presbyopia — the normal age-related loss of near focusing ability that typically begins around age 40–45. A 45-year-old who has LASIK will see clearly in the distance but will still need reading glasses for close work. This is a natural process and not a failure of the procedure. Options like monovision LASIK (where one eye is corrected for distance and one for near) or multifocal lens approaches can reduce reading glass dependence, and we discuss these options with every patient over 40.