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

Laser eye surgery uses a precisely focused excimer laser beam to permanently reshape the cornea — the clear front surface of the eye — correcting refractive errors (focusing faults) and reducing or eliminating dependence on glasses or contact lenses. The excimer laser operates at a wavelength of 193 nanometres, removing microscopic amounts of corneal tissue with sub-micron precision without generating heat in adjacent tissue. By flattening the central cornea (for myopia), steepening it (for hyperopia), or creating an asymmetric correction (for astigmatism), the cornea's optical power is precisely altered to bring light to a sharp focus on the retina. The three principal laser eye surgery techniques are: LASIK (laser in situ keratomileusis) — a hinged corneal flap is created and the laser applied to the underlying stromal tissue; PRK (photorefractive keratectomy) — no flap, the laser is applied directly to the corneal surface after removing the epithelium; and LASEK — a variant of PRK where the epithelial sheet is preserved and replaced. LASIK offers the fastest recovery (functional vision in 24 hours); PRK avoids flap-related complications at the cost of 3–5 days of discomfort while the epithelium regenerates. SMILE (small incision lenticule extraction) is a newer flapless technique increasingly available at specialist centres.

Laser refractive surgery candidacy requires a comprehensive pre-operative assessment. Suitable candidates must be aged 18 or above (corneal prescription stable for a minimum of 12 months), with myopia up to approximately -10 to -12 dioptres (D), hyperopia up to +4 to +6 D, and astigmatism up to 5–6 D. Adequate corneal thickness is essential — a minimum residual stromal bed of 250–280 microns must remain after the laser treatment, assessed by corneal topography and pachymetry. Contraindications to LASIK include: keratoconus (progressive corneal ectasia), even forme fruste — detectable only by corneal topography screening; thin corneas inadequate for the calculated ablation depth; severe dry eye disease (laser surgery worsens dry eye for several months); corneal scars or active corneal disease; autoimmune disease affecting the ocular surface; and uncontrolled glaucoma. Unstable refraction (prescription changing more than 0.5 D per year) contraindicates surgery until two consecutive stable measurements are confirmed 12 months apart. PRK is preferred over LASIK for patients with thin corneas, contact sport participants (where flap dislodgement is a risk), military or professional aviation candidates (where corneal flap stability is required by occupational standards), and surgeons who work in high-dust environments.

The eye is numbed with topical proxymetacaine anaesthetic drops — no injections or general anaesthesia are required. A lid speculum holds the eye open and prevents blinking. For LASIK, a femtosecond laser (iFS, Ziemer, or Alcon FS200) creates a precise corneal flap by delivering thousands of laser pulses in a raster pattern at a predetermined depth (90–110 microns) to create a smooth tissue plane; the hinged flap is lifted and the stromal surface dried. The excimer laser (Wavelight EX500, Schwind, or Visx) then applies the individually programmed treatment to the stromal bed under wavefront guidance — the number of laser pulses is calculated from the patient's full manifest refraction and corneal topography. For a -5.00 D correction, approximately 70–80 microns of stromal tissue is removed from the central 6.0–6.5 mm optical zone. The flap is replaced and smoothed; it adheres within minutes by the natural suction of the corneal collagen. No sutures are required. For PRK, the epithelium is removed by gentle debridement with a blunt spatula or 20% alcohol application. The excimer laser treatment is identical to LASIK, applied to the anterior stroma. A bandage contact lens is placed after PRK to protect the surface while the epithelium regrows over 4–5 days. Treatment of both eyes takes approximately 20–30 minutes total; the laser itself fires for 20–40 seconds per eye for a moderate correction.

Laser eye surgery has one of the highest patient satisfaction rates of any elective procedure — exceeding 95% in the world's largest systematic review (Blumenstock et al., 2023, reviewing 97 studies and 67,893 eyes). Over 95% of patients achieve uncorrected distance visual acuity of 20/40 or better (legal driving standard) after LASIK; approximately 85–90% achieve 20/20 (normal acuity). Approximately 5–10% of eyes require a secondary enhancement procedure (re-treatment with an additional laser application) 3–12 months after primary surgery to fine-tune the result, bringing final satisfaction rates above 98%. The correction is permanent — the corneal reshaping does not revert — though some regression may occur in very high myopes over 5–10 years. LASIK offers rapid rehabilitation: most patients drive and return to work the next day. PRK achieves equivalent long-term visual outcomes but with a slower recovery. Freedom from glasses enables sports participation, swimming, occupational activities, and lifestyle benefits not possible with spectacle correction. Visual quality metrics including contrast sensitivity, wavefront aberration, and night vision performance are maintained or improved compared with spectacle-corrected vision in most patients, particularly when wavefront-guided or topography-guided laser ablation profiles are used.

Dry eye symptoms — reduced tear film stability, grittiness, fluctuating vision, and photophobia — affect 30–50% of patients in the first 1–6 months after LASIK and are related to severing of corneal sensory nerves during flap creation. Symptoms resolve in most patients within 6–12 months; severe persistent dry eye is uncommon (under 5%) and is managed with preservative-free artificial tears, omega-3 supplementation, punctal plugs, and cyclosporin eye drops. Halos, glare, and star-bursting around lights at night affect 15–25% of patients and are related to the optical zone diameter relative to the mesopic (low-light) pupil size; modern large optical zones (6.0–6.5 mm) and customised ablations have significantly reduced this complication versus older techniques. Under-correction or over-correction — residual refractive error — occurs in 5–10% of eyes and is usually addressable by re-treatment after 3 months. LASIK flap complications — flap striae, epithelial ingrowth, diffuse lamellar keratitis — occur in under 1% with modern femtosecond laser flap creation. Post-LASIK ectasia — progressive corneal thinning and steepening leading to increasing myopia and irregular astigmatism — is the most feared serious complication, occurring in approximately 1 in 2,500 LASIK eyes; it is almost entirely preventable by rigorous pre-operative screening excluding keratoconus and thin corneas. Corneal haze after PRK occurs in 1–3% and is prevented by post-operative topical mitomycin C application and UV protection.

After LASIK, patients notice significant visual improvement within hours. Mild light sensitivity, mild tearing, and a scratchy sensation resolve within 24 hours. Most patients drive and return to desk work the following day. Activities to avoid: rubbing the eyes for 1 month (risk of flap displacement); swimming for 4 weeks; contact sports for 4–6 weeks (wear protective goggles when returning). After PRK, the bandage contact lens is worn for 4–5 days while the corneal epithelium regenerates — vision is blurred during this period and mild-to-moderate pain (similar to corneal abrasion) is expected, managed with oral NSAIDs and prescribed analgesic drops. Vision stabilises progressively over 1–3 months after PRK (slower than LASIK). Post-operative eye drops prescribed for both procedures: antibiotic drops (4 times daily for 5 days to prevent infection), topical steroid or NSAID drops (4 times daily for 4 weeks to reduce inflammation and refractive regression), and preservative-free lubricating drops (as frequently as needed for dry eye management). The first post-operative review is the following morning; subsequent reviews at 1 week, 1 month, 3 months, and 12 months monitor visual acuity, refraction, corneal topography, and surface healing. Enhancement procedures, if needed, are scheduled no earlier than 3 months after primary surgery once refraction has stabilised.