LASIK vs SMILE Eye Surgery in Shanghai: Which Is Right for You?

Refractive surgery has transformed the lives of hundreds of millions of people worldwide. For the large proportion of the global population that wears glasses or contact lenses, the prospect of clear, unaided vision is compelling. Shanghai has become one of the world's leading centers for refractive surgery, combining high procedure volumes, internationally trained ophthalmologists, state-of-the-art laser platforms, and costs significantly lower than in Western countries or other parts of Asia.

Understanding Refractive Errors

The eye focuses light through the cornea and lens onto the retina. Refractive errors occur when the eye's optical power does not match its axial length:

• Myopia (short-sightedness): The eye is too long or the cornea too curved. Light focuses in front of the retina. Measured in negative diopters (e.g., -3.00 D). Highly prevalent in East Asia, affecting 80-90% of young adults in some Chinese cities.
• Hyperopia (long-sightedness): The eye is too short or the cornea too flat. Light focuses behind the retina. Measured in positive diopters (e.g., +2.00 D).
• Astigmatism: Irregular corneal curvature causes light to focus at multiple points, resulting in blurred vision at all distances. Often coexists with myopia or hyperopia.
• Presbyopia: Age-related loss of near focusing ability due to reduced lens elasticity. Affects virtually everyone over 45. Not correctable by standard LASIK or SMILE, but addressable with monovision correction, multifocal lens implants, or corneal inlays.

How Laser Refractive Surgery Works

All laser refractive procedures permanently reshape the cornea to alter its refractive power. The cornea contributes approximately two-thirds of the eye's total refractive power, making it the primary target for correction. The excimer laser removes corneal tissue with sub-micron precision through photoablation. The femtosecond laser uses ultrashort infrared pulses to create precise tissue planes and is used in LASIK flap creation and exclusively in SMILE.

LASIK: Laser-Assisted In Situ Keratomileusis

LASIK is the most widely performed refractive surgery globally, with over 40 million procedures performed worldwide and an excellent safety record accumulated over 25+ years.

How LASIK Works

1. Flap creation: A thin hinged flap of corneal tissue (approximately 100-120 micrometres thick) is created using a femtosecond laser. The flap is lifted to expose the underlying corneal stroma.
2. Stromal ablation: An excimer laser reshapes the exposed stromal bed according to the patient's refractive prescription. For myopia, tissue is removed from the central cornea to flatten it; for hyperopia, the periphery is ablated to steepen the centre.
3. Flap repositioning: The flap is replaced over the treated stroma, adhering without sutures through natural surface tension and stromal bonding.

The procedure takes approximately 10-15 minutes per eye. Vision improvement is typically dramatic within 24 hours.

Advanced LASIK Variants

• Wavefront-guided LASIK: Measures higher-order aberrations beyond sphere and cylinder and incorporates their correction into the ablation profile. Associated with better quality of vision in low-light conditions and reduced halos and glare.
• Topography-guided LASIK (Contoura Vision): Uses corneal topography data to create a highly individualized ablation profile correcting both refractive error and corneal surface irregularities. Particularly beneficial for irregular astigmatism. FDA-approved and available at leading Shanghai centers.

Advantages of LASIK

• Rapid visual recovery - most patients achieve functional vision within 24 hours
• Minimal discomfort - the procedure is painless with mild irritation for a few hours post-operatively
• Broad treatment range - effective for myopia up to approximately -12.00 D, hyperopia up to +6.00 D, and astigmatism up to 6.00 D
• Enhancement-friendly - the flap can be re-lifted for retreatment procedures
• Extensive long-term safety data spanning 25+ years

Limitations and Risks of LASIK

• Flap-related complications: The corneal flap is a permanent structural change. Flap dislocation can occur with significant eye trauma years after surgery. Flap striae, epithelial ingrowth, and diffuse lamellar keratitis (DLK) are rare but recognized complications.
• Dry eye: LASIK severs corneal nerves during flap creation, reducing corneal sensation and tear secretion. Dry eye symptoms are common in the first 3-6 months and usually resolve, but can be persistent in predisposed individuals. Pre-existing dry eye is a relative contraindication.
• Corneal ectasia: Progressive corneal thinning and steepening following LASIK, analogous to keratoconus. A rare but serious complication most commonly occurring in patients with pre-existing subclinical corneal weakness. Rigorous pre-operative screening is essential.
• Halos and glare: Particularly in low-light conditions. Wavefront-guided treatment and appropriate optical zone sizing minimize this risk.

SMILE: Small Incision Lenticule Extraction

SMILE is a newer, flapless refractive procedure developed by Carl Zeiss Meditec, performed exclusively with the VisuMax femtosecond laser. SMILE is now the most commonly performed refractive procedure in China, reflecting both the high volume of myopic patients and rapid adoption by Chinese ophthalmologists.

How SMILE Works

1. Lenticule creation: The femtosecond laser creates two curved tissue planes within the corneal stroma, defining a disc-shaped piece of tissue called a lenticule whose shape encodes the refractive correction.
2. Small incision: A small arc-shaped incision (2-4 mm, compared to the 20 mm flap edge in LASIK) is made at the corneal periphery.
3. Lenticule extraction: The surgeon uses fine instruments to dissect and remove the lenticule through the small incision, reshaping the cornea and correcting the refractive error.

No excimer laser is used. The entire procedure is performed with a single femtosecond laser system. Total laser time is approximately 25-30 seconds per eye.

Advantages of SMILE

• Flapless - no flap complications: Eliminates flap dislocation risk entirely. Particularly advantageous for patients in contact sports, martial arts, or military roles where eye trauma is a risk.
• Better corneal biomechanical stability: SMILE preserves more of the anterior corneal stroma - the strongest layer - compared to LASIK. Biomechanical studies consistently show superior corneal tensile strength retention after SMILE.
• Less dry eye: The small incision severs fewer corneal nerves than the LASIK flap, resulting in better preservation of corneal sensation and tear function. Dry eye symptoms are less frequent and less severe after SMILE.
• Equivalent visual outcomes: Multiple randomized controlled trials and meta-analyses confirm that SMILE achieves visual acuity outcomes equivalent to LASIK for myopia correction.

Limitations of SMILE

• Slower visual recovery: Most patients achieve functional vision within 1-3 days rather than 24 hours, with full stabilization over 1-3 months.
• Limited hyperopia correction: SMILE is validated primarily for myopia and myopic astigmatism. Hyperopia correction (SMILE+) is in development but not yet widely available.
• Enhancement is more complex: Cannot be performed by re-treating through the original incision. Options include surface ablation (PRK) on top of SMILE or conversion to a flap procedure.
• Surgeon learning curve: Lenticule dissection requires tactile skill and experience. High-volume Shanghai centers have surgeons with thousands of SMILE procedures.

PRK / TransPRK: Surface Ablation

Surface ablation removes or displaces the corneal epithelium and applies the excimer laser directly to the corneal surface without creating a flap or lenticule. It is preferred for patients with thin corneas, flat corneas, irregular topography, or high-risk occupations where even SMILE's small incision is a concern. The trade-off is a longer recovery - the epithelium takes 3-5 days to heal with significant discomfort, and full visual stabilization takes 1-3 months. Mitomycin C (MMC) is applied intraoperatively to reduce corneal haze risk.

Implantable Collamer Lens (ICL)

For patients with high myopia, thin corneas, or contraindications to laser surgery, the EVO ICL (Implantable Collamer Lens) offers an excellent alternative. A soft, foldable lens is implanted between the iris and the natural crystalline lens through a small corneal incision, without removing any corneal tissue.

ICL is particularly well-suited for:

• High myopia (-8.00 D to -20.00 D) beyond the safe range of laser correction
• Thin corneas that cannot safely undergo laser ablation
• Dry eye that contraindicates LASIK
• Patients who want a reversible procedure (the ICL can be removed)

The EVO ICL has an outstanding safety record with visual outcomes often superior to laser correction for high myopia. ICL implantation is widely performed in Shanghai at costs significantly lower than in Western countries.

Pre-Operative Screening: What to Expect

Thorough pre-operative screening is the most important determinant of refractive surgery safety. A comprehensive workup at a Shanghai refractive center includes:

• Refraction: Manifest and cycloplegic (dilated) refraction to determine the accurate refractive prescription.
• Corneal topography: Maps the anterior corneal surface curvature. Identifies irregular astigmatism and keratoconus.
• Corneal tomography (Pentacam / Galilei): Full 3D map of the cornea including posterior surface, pachymetry map, and keratoconus indices. Essential for detecting subclinical keratoconus and assessing ectasia risk.
• Corneal biomechanics (Corvis ST / ORA): Measures corneal stiffness and deformation response. Adds an additional layer of ectasia risk assessment.
• Pachymetry: Measures corneal thickness. Minimum residual stromal bed thickness after ablation should be 250-280 micrometres (LASIK) or 300 micrometres (PRK).
• Pupillometry: Measures pupil diameter in dark conditions. Large pupils relative to the optical zone increase halos and glare risk.
• Tear film assessment: Schirmer test, tear break-up time (TBUT), and meibomian gland evaluation to assess dry eye risk.
• Anterior segment OCT: High-resolution imaging of corneal layers and anterior chamber structures.
• Endothelial cell count and anterior chamber depth: Required for ICL candidates.

Contact lenses must be removed before screening: soft lenses for at least 1 week, rigid gas-permeable lenses for at least 3-4 weeks.

LASIK vs SMILE: Head-to-Head Comparison

Candidacy Criteria

General candidacy criteria for laser refractive surgery include age 18-21 or older with stable prescription for at least 1-2 years, myopia up to approximately -10.00 to -12.00 D, hyperopia up to +4.00 to +6.00 D (LASIK), astigmatism up to 5.00-6.00 D, adequate corneal thickness (480-500 micrometres or more for LASIK/SMILE), normal corneal topography and tomography, no active ocular disease, no autoimmune conditions that impair wound healing, and not pregnant or breastfeeding.

The Patient Journey in Shanghai

For international patients, refractive surgery in Shanghai can typically be completed within a short visit:

• Day 1 - Pre-operative screening: Comprehensive workup (2-3 hours). Contact lenses must have been removed in advance.
• Day 2 or 3 - Surgery: 10-20 minutes per eye. Patients rest for 1-2 hours post-operatively and are discharged with eye drops and protective shields.
• Day 3-4 - First post-operative check: Visual acuity and slit-lamp examination.
• Day 7 - Second check: Confirms healing and refraction. Most patients cleared for normal activities.
• Flying home: Most surgeons clear patients for air travel 3-7 days after LASIK or SMILE. Use lubricating drops frequently during the flight as cabin air is dry.

Follow-up at 1 and 3 months can be performed with a local ophthalmologist, with reports shared with the Shanghai surgeon.

Cost Reference

• Pre-operative screening: USD 100-250
• Standard LASIK (both eyes): USD 1,500-2,800
• Wavefront / Topography-guided LASIK (both eyes): USD 2,000-3,500
• SMILE (both eyes): USD 2,000-3,500
• PRK / TransPRK (both eyes): USD 1,200-2,200
• ICL implantation (both eyes): USD 3,500-6,500

Comparable procedures in the United States typically cost USD 4,000-6,000 for LASIK and USD 8,000-12,000 for ICL. In Singapore, SMILE typically costs SGD 3,500-5,500 per eye.

Frequently Asked Questions

Is refractive surgery permanent?
The corneal reshaping is permanent. However, the eye continues to change with age - presbyopia develops after 40-45 regardless of prior refractive surgery, and some patients experience mild myopic regression over years, particularly with higher initial prescriptions.

What is the risk of losing vision?
The risk of significant permanent vision loss from LASIK or SMILE at a reputable center with thorough screening is extremely low - estimated at less than 1 in 10,000 procedures. The most serious risk is corneal ectasia, which is largely preventable with rigorous pre-operative screening.

I have been told I am not suitable for LASIK. Can I still have refractive surgery?
Not necessarily ruled out. Patients unsuitable for LASIK may still be candidates for SMILE (if the contraindication is flap-related), PRK (if the cornea is thin but not too thin), or ICL (if the cornea is too thin for any ablative procedure). A comprehensive screening will clarify all available options.

How do I choose a refractive surgery center in Shanghai?
Key factors include procedure volume, range of screening technology, surgeon experience with the recommended procedure, and availability of post-operative follow-up. Shanghai's leading ophthalmology hospitals - including Shanghai Eye, Ear, Nose and Throat Hospital (EENT), Zhongshan Hospital Eye Center, and Aier Eye Hospital - are high-volume centers with comprehensive refractive programs.

Explore Your Options in Shanghai

If you are considering LASIK, SMILE, or ICL in Shanghai, China Medical Concierge (CMCS) can coordinate your screening appointment, translation support, and logistics. Contact us to get started.