LASIK Eye Surgery — How It Works, Benefits & Recovery — Procedure Guide, Recovery & Risks | MyMedicPlus

LASIK (Laser-Assisted In Situ Keratomileusis) is the most widely performed elective surgical procedure in the world, with over 30 million procedures performed annually. It uses a precisely programmed excimer laser to reshape the cornea — the clear front surface of the eye — to correct refractive errors including myopia (short-sightedness up to -12 dioptres), hyperopia (long-sightedness up to +6 dioptres), and astigmatism (irregular corneal curvature up to ±6 dioptres). The fundamental principle is that by altering the curvature of the cornea, LASIK changes how light is focused onto the retina, eliminating or significantly reducing the need for spectacles or contact lenses. The procedure involves creating a thin protective hinged flap in the outer corneal tissue (using either a mechanical microkeratome or a femtosecond laser — the latter is termed 'all-laser' or 'bladeless' LASIK), lifting the flap to expose the underlying corneal stroma, applying precisely calculated excimer laser pulses to reshape the stromal bed, and repositioning the flap, which adheres naturally by biomolecular forces without sutures. The excimer laser (wavelength 193 nm) works by photoablation — breaking molecular bonds in corneal tissue without generating heat, allowing nanometre-precision tissue removal guided by a personalised treatment plan derived from wavefront aberrometry mapping. LASIK has consistently shown high safety, efficacy, and patient satisfaction over 25 years of large-scale clinical use.

LASIK candidacy requires a comprehensive pre-operative evaluation that assesses multiple factors to identify suitability and minimise the risk of complications. Age: patients must be at least 18–21 years old (most surgeons prefer 21+) with a stable refraction — no change greater than 0.5 dioptres in the preceding 12 months — to prevent regression after treatment. Corneal thickness is critical: a minimum residual stromal bed of 250–300 µm must remain after flap creation and ablation to prevent post-operative ectasia; pachymetry must confirm adequate corneal thickness (typically above 480–500 µm). Corneal shape: topography and tomography (Pentacam) must exclude keratoconus, subclinical keratoconus (forme fruste), or any corneal thinning pattern — these are absolute contraindications because LASIK further weakens the cornea and risks progressive ectasia. Pupil size: large scotopic pupils (above 7 mm in darkness) may experience more night vision disturbances, though modern large optical zones reduce this risk. Pre-existing dry eye disease requires treatment and reassessment before LASIK, as the procedure temporarily worsens dry eye by transecting corneal nerves. Contraindications include: keratoconus or ectasia; insufficient corneal thickness; unstable refraction; severe dry eye unresponsive to treatment; active autoimmune disease; pregnancy or breastfeeding; and unrealistic expectations. Patients unsuitable for LASIK may be candidates for alternative refractive procedures: SMILE (Small Incision Lenticule Extraction), PRK/LASEK (surface ablation without a flap), or implantable collamer lens (ICL) for high prescriptions.

LASIK is an outpatient procedure performed in a dedicated refractive surgery suite. Both eyes are typically treated on the same day. Anaesthetic eye drops are administered; no injections or sedation are required. The eye is held open by a speculum during the procedure. For femtosecond ('bladeless') LASIK flap creation: a femtosecond laser (IntraLase, VisuMax) is applied to the eye surface via a suction interface; it delivers thousands of precisely spaced laser pulses at a programmed depth (typically 100–140 µm below the corneal surface) that create a plane of microscopic gas bubbles, which coalesce to form the flap separation. The laser takes approximately 15–20 seconds per eye. The flap is then gently lifted by the surgeon using a spatula and folded back on its hinge. The excimer laser treatment is then applied to the exposed stromal bed: the patient fixates on a central target light while the tracker system maintains alignment; the computer-controlled laser delivers the personalised ablation pattern (typically 15–45 seconds at energy densities of 160–180 mJ/cm²) removing tissue from the central or paracentral cornea to correct the refractive error. Myopia correction flattens the central cornea; hyperopia correction steepens the centre by removing tissue from the periphery. The flap is repositioned precisely using anatomical landmarks, irrigated, and gently smoothed — it bonds to the underlying stroma within seconds by adhesion forces. No sutures are required. The procedure takes approximately 10–15 minutes per eye.

LASIK delivers exceptionally high rates of patient satisfaction and visual outcomes that are unmatched by any other vision correction modality. The largest published clinical study — a meta-analysis of 97 studies comprising 67,893 eyes — found that 99.5% of LASIK patients achieve better than 20/40 vision without correction (legal driving vision), and 90% achieve 20/20 or better uncorrected visual acuity. Patient satisfaction rates consistently exceed 95–96% in independent surveys, including those conducted by regulatory authorities. The speed of visual recovery is a major advantage: most patients achieve functional vision for driving and working within 24–48 hours. Night vision quality has improved significantly with modern treatments using wide optical zones (typically 6–6.5 mm) and wavefront-guided ablation profiles that minimise higher-order aberrations. Wavefront-guided LASIK (using aberrometry mapping of the eye's unique optical errors) can improve upon the optical quality of spectacle correction in some patients, producing 'super-vision' outcomes. The procedure eliminates both the direct costs of spectacles and contact lenses and the cumulative risks of contact lens wear (infective keratitis, corneal neovascularisation). Long-term studies at 10–15 years confirm stability of LASIK outcomes for the majority of patients, with clinically significant regression uncommon in correctly treated eyes.

LASIK is one of the safest elective procedures performed in medicine, with serious complications occurring in well under 1% of procedures at accredited refractive centres. However, patients should understand all potential adverse outcomes before proceeding. Dry eye syndrome is the most common side effect, affecting approximately 20–40% of patients in the first 3–6 months; it typically improves spontaneously but may persist in a minority. Clinically significant, treatment-requiring dry eye affects approximately 5% of LASIK patients at 12 months; patients with pre-existing dry eye are at higher risk. Night vision disturbances — halos, starbursts, and glare around lights — are reported by 20–30% of patients initially; these reduce significantly over 3–6 months as the cornea heals, but may persist in a small proportion. Flap complications — flap striae (wrinkles), epithelial ingrowth under the flap, or rarely flap dislocation from trauma — are specific to LASIK; they are rare (under 1%) and most are manageable. Diffuse lamellar keratitis (DLK, 'Sands of the Sahara') is an inflammatory reaction under the flap occurring in approximately 0.2–1% of procedures, treatable with intensive topical steroids. Under- or over-correction occurs in 5–10% of treated eyes — an enhancement procedure can be performed after 12 months once the refraction is stable. Post-LASIK ectasia — progressive corneal thinning and bulging similar to keratoconus — is the most serious long-term complication (estimated 0.04–0.6%), occurring in patients with insufficient residual corneal tissue or undetected subclinical ectasia; rigorous pre-operative screening is the primary preventive measure.

LASIK recovery is notably rapid compared to most surgical procedures. Immediately after the procedure, vision is blurry or hazy and the eyes feel gritty, watery, or mildly uncomfortable; this resolves within 3–4 hours as the flap adheres and the topical anaesthetic wears off. Patients are advised to go home, keep their eyes closed, and rest for 4–6 hours. Functional vision for most activities typically returns within 24 hours; many patients return to work the next day. Driving is safe once vision meets legal requirements — for most patients, this is achieved within 24–48 hours, confirmed at the next-day review appointment. Prescribed eye drop regimen includes: antibiotic drops (ciprofloxacin or chloramphenicol) for 5–7 days to prevent infection; topical corticosteroid drops (fluorometholone) for 1–2 weeks to control post-operative inflammation; and intensive lubricating drops (preservative-free artificial tears) used frequently (initially every 30–60 minutes when awake) for at least 3 months to manage post-LASIK dry eye. Eye rubbing must be strictly avoided for at least one month, as it risks displacing the flap in the early healing period. Swimming and contact water sports are avoided for 4 weeks; eye make-up for 2 weeks. Follow-up appointments are scheduled at 1 day, 1 week, 1 month, 3 months, and 12 months. Refraction stabilises by 1–3 months; if residual prescription above 0.75 dioptres persists after 12 months, a laser enhancement is considered.