01Purpose and principlesWhat the treatment does and how it fits into care.
Refractive surgery aims to reduce dependence on spectacles or contact lenses by changing the eye's optical system. It is an elective functional intervention with several different anatomical approaches. The procedure that fits one patient's prescription may be inappropriate for another person's corneal shape, natural lens, ocular surface or visual demands. A useful assessment begins with the patient's goals and the best available corrected vision, then asks whether surgery can achieve a worthwhile result at acceptable risk.
Corneal laser correction leaves the natural lens inside the eye. LASIK creates a flap and reshapes the underlying cornea; surface procedures such as PRK, LASEK and transPRK remove or displace the epithelium before reshaping; SMILE removes a laser-created stromal lenticule through a small incision. These approaches differ in wound configuration and recovery, but each alters corneal tissue and requires careful screening for ectasia risk. A smaller incision or absence of a flap does not make preoperative assessment unnecessary.
Lens-based options act at a different optical plane. A phakic IOL adds an implant while retaining the natural lens and its remaining accommodation. Refractive lens exchange replaces the natural lens, using principles similar to cataract surgery even when the lens is not yet significantly cloudy. It therefore carries intraocular risks and permanently removes natural accommodation. None of these operations prevents future presbyopia-related needs in an otherwise phakic eye, retinal disease associated with high axial myopia or all later changes in prescription.
Key points
- Corneal laser procedures alter focusing power by changing corneal shape; they do not shorten the eye.
- LASIK reshapes beneath a flap, surface procedures reshape after epithelial removal, and SMILE extracts a stromal lenticule.
- Phakic implants leave the natural lens in place; refractive lens exchange removes and replaces it.
- Suitability depends on stable refraction, healthy ocular structures, adequate corneal anatomy and realistic goals.
- Discuss dry eye, glare, residual prescription and rare sight-threatening complications alongside the expected benefit.
- Preserve the surgical history because later pressure assessment and cataract implant calculations may be affected.
02Indications, selection and cautionsWho may benefit, who needs urgent treatment and important alternatives.
Confirm adult age, documented prescription stability and healthy eyes. Review previous prescriptions rather than relying only on today's measurement. Continuing myopic progression, a suspicious corneal shape, active ocular surface disease or unstable systemic factors may justify deferral or a different approach.
LASIK generally offers relatively rapid functional recovery but leaves a flap that can be disturbed by trauma. Surface ablation requires epithelial healing and typically has a slower, more uncomfortable early recovery. SMILE avoids a LASIK flap but still creates an intrastromal interface and has its own suitability limits.
A phakic implant may be considered when the prescription is unsuitable for corneal laser treatment, provided the anatomy can accommodate it safely. It requires surveillance for pressure, lens and endothelial problems. Lens exchange removes future natural-lens cataract risk but introduces the operative risks of lens extraction, including retinal concerns in high myopia.
Mild early blur, irritation and altered night vision may settle, but the trend matters. Increasing symptoms, a new focal corneal opacity, significant inflammation or sudden loss require examination. Gradual later ghosting can reflect surface disease, residual error, regression or ectasia and should not automatically be labelled a need for more laser.
03Assessment before treatmentTests and checks that guide safe selection.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
Repeated refraction and visual acuityFirst step - Why
- Confirm stability and establish the best corrected visual potential.
- Interpretation and limitations
- Use reliable current measurements and prior records. Investigate unexplained reduction in best-corrected acuity before elective treatment. The intended result should reflect the person's vision with optimal correction and any limitation from amblyopia or retinal disease.
- 02
Corneal topography, tomography and thickness - Why
- Assess shape, ectasia risk and the tissue available for treatment.
- Interpretation and limitations
- Suspicious asymmetry, irregularity or inadequate residual tissue can preclude a proposed laser procedure. A prescription within a published treatment range does not establish suitability by itself. Contact lens-related corneal warpage may require a lens-free interval and repeated measurements.
- 03
Ocular surface and anterior segment examination - Why
- Identify inflammation, dry eye and anatomy relevant to an implant.
- Interpretation and limitations
- Treat significant surface disease before interpreting final measurements or proceeding. For phakic lens surgery, assess the anterior chamber and corneal endothelium as required by the proposed implant. Cataract, glaucoma or other pathology may change which procedure, if any, is appropriate.
- 04
Pressure, optic nerve and retinal assessment - Why
- Establish ocular health and a baseline for later surveillance.
- Interpretation and limitations
- Assess pressure and the optic nerve and examine the retina, particularly in high myopia. After corneal laser surgery, standard tonometry can underestimate pressure because corneal properties have changed. A low reading must be interpreted alongside nerve appearance, fields and imaging when glaucoma is suspected.
04Treatment approachPreparation, options, escalation and aftercare.
01Assess and discussChoose a realistic refractive planFirst stepAn adult requests a procedure to reduce reliance on optical aids.+
- 1Clarify visual priorities, occupation, sports, night driving and tolerance of possible residual spectacle use.
- 2Complete refractive, corneal and ocular health assessment and discuss spectacles or contact lenses as continuing alternatives.
- 3Explain the proposed anatomical change, expected recovery and individual risks without presenting one technique as universally superior.
- 4Allow a considered consent discussion with the operating surgeon, time for questions and a clear understanding of aftercare and further-treatment arrangements.
02Procedure selectionMatch the intervention to the eyeAssessment suggests that a refractive intervention may offer an acceptable benefit.+
- 1Consider corneal laser correction only when shape, tissue reserve, ocular health and refractive stability support the proposed treatment.
- 2Discuss phakic implantation when appropriate for the refractive error and anatomy, including the need for continuing intraocular surveillance.
- 3For lens exchange, explain loss of natural accommodation and risks associated with lens extraction, especially retinal risk in a long eye.
- 4Agree the optical target and any monovision strategy with its binocular trade-offs, using a trial correction when helpful before a permanent change.
03Postoperative concernSeparate expected recovery from a complicationA patient reports new or persistent symptoms after refractive surgery.+
- 1Establish the exact procedure, date, prescribed drops, initial recovery and subsequent direction of change.
- 2Arrange same-day ophthalmic review for worsening pain, redness, photophobia or vision, communicating any trauma or corneal opacity.
- 3Have the specialist distinguish infection, sterile inflammation, epithelial or flap problems and pressure elevation before changing steroid treatment.
- 4For later progressive blur, obtain repeat refraction and corneal imaging to assess ectasia and other causes before considering an enhancement.
05Complications, monitoring and follow-upAdverse effects, response and longer-term review.
- Follow the operating service's early review schedule and prescribed topical antibiotic, anti-inflammatory and lubricant plan, with explicit instructions about treatment duration and any steroid taper.
- Assess recovery of vision, comfort, epithelial healing and procedure-specific structures; unexpected deterioration should bring the review forward.
- Monitor intraocular pressure when postoperative steroid exposure or other risk factors warrant it, interpreting readings in the context of altered corneal biomechanics.
- In phakic implant recipients, maintain the planned checks of lens position, pressure, corneal endothelium and the natural lens rather than assuming a clear early result ends surveillance.
- Retain preoperative refraction, corneal measurements and procedure details for later eye care, while continuing retinal and glaucoma assessment according to the person's underlying risk.
06Special situationsVariants, exceptions and circumstances that change the usual approach.
Ectasia is a structural problem
An increasingly irregular cornea after refractive surgery needs corneal specialist assessment. Management may include specialist optical correction and corneal collagen cross-linking to stabilise appropriate progressive disease. Cross-linking aims to limit structural progression; it is not simply a stronger refractive correction or a guarantee of normal unaided acuity.
Later cataract calculations change
Previous corneal laser treatment alters assumptions used in standard IOL calculations. Patients should tell every future cataract surgeon about it even if the original prescription seems unimportant. Historical information can help, but the surgeon still needs current measurements and an appropriate calculation method.
Optical correction does not erase axial risk
An eye that was highly myopic because of its length remains long after the cornea has been reshaped. Clear unaided distance vision therefore coexists with continuing susceptibility to retinal problems. Safety-net advice should follow ocular anatomy and history, not the new spectacle prescription alone.
Persistent symptoms deserve careful attention
Dry eye, glare or loss of visual quality can affect daily life even when measured acuity looks excellent. Take the complaint seriously, assess the ocular surface and optics, and discuss the findings with the operating surgeon. Repeating treatment without identifying the mechanism may compound the problem.
07Common pitfallsFrequent interpretation and management errors.
- 01
Assuming a stable-looking prescription is enough to approve laser treatment without corneal imaging.
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Describing SMILE or surface treatment as carrying no ectasia or infection risk.
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Promising that refractive lens exchange restores the accommodation of a young natural lens.
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Restarting steroid drops for a painful postoperative eye before excluding infection or pressure-related disease.
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Using an apparently normal postoperative pressure reading to dismiss suspicious optic nerve or visual field findings.