Refractive Surgery for Residents: PRK, LASIK, SMILE and ICL

Last updated: October 2026

Refractive surgery is elective surgery on healthy eyes, so patient selection matters more than technique. This page covers the main procedures, who is a good candidate, and the complications every resident should recognise.

The main procedures

Who is a good candidate?

• Adult (usually 18 or older) with a stable refraction (typically no more than about 0.5 D change over a year).
• Realistic expectations, and an understanding that reading glasses will still be needed with age.
• Healthy ocular surface; treat dry eye and blepharitis before deciding.
• Normal corneal tomography and adequate corneal thickness for the planned treatment.

Who should not have laser vision correction?

• Keratoconus, forme fruste keratoconus, or suspicious tomography
• Unstable refraction, pregnancy or breastfeeding
• Uncontrolled autoimmune or collagen vascular disease
• Active ocular infection or inflammation, severe dry eye, or a history of herpetic keratitis (relative)
• Unrealistic expectations

Ectasia: the complication you must prevent

• Key risk factors: abnormal pre-operative tomography, thin cornea, thin residual stromal bed, young age, and high myopic correction.
• A residual stromal bed below about 250–300 µm is generally considered unsafe for LASIK.
• Percent tissue altered (PTA) of 40% or more is a recognised risk factor.
• Screening is covered in detail in our topography and tomography tips.

LASIK flap complications to recognise

• Diffuse lamellar keratitis (DLK): sterile, sand-like inflammation at the interface in the first days. Treat with intensive steroids; grade 4 can cause scarring.
• Infectious keratitis: focal infiltrate, pain, worsening after the first days. Lift the flap, culture and treat. Atypical mycobacteria are a classic cause.
• Epithelial ingrowth: grey nests of epithelium under the flap edge. Lift and scrape if progressive or affecting vision.
• Flap striae and displacement: look for wrinkles in retroillumination. Refloat and smooth early.

Phakic IOL pearls

• Adequate anterior chamber depth and endothelial cell count are prerequisites; follow the manufacturer's criteria.
• The vault (distance between the ICL and the natural lens) is checked after surgery. Too low a vault risks cataract; too high risks angle narrowing and raised IOP.
• Monitor IOP, the anterior chamber angle and endothelial cell density over the long term.

After refractive surgery: remember it forever

• Standard keratometry is unreliable after corneal refractive surgery. Use special methods for IOL power calculation. See post-refractive IOL calculation.
• Applanation IOP reads falsely low after myopic laser correction, because the cornea is thinner.

Patient-friendly comparisons: LASIK vs ICL and LASIK at Sadbhaav.