In small incision lenticule extraction (SMILE), the optical correction is achieved by:

• A Excimer laser ablation of the corneal stroma after creating a hinged flap with a microkeratome
• B A femtosecond laser that creates an intrastromal lenticule of precise shape which is then extracted through a 2–4 mm incision without creating a corneal flap ✓
• C Photorefractive ablation of the epithelium and anterior stroma surface without flap creation
• D Insertion of a phakic intraocular lens through a corneal incision

Explanation

SMILE uses a femtosecond laser to create two curved intrastromal cuts defining a lenticule of calculated shape within the corneal stroma. The lenticule is then manually dissected and extracted through a small (2–4 mm) peripheral incision — no flap is created. This preserves more corneal biomechanical integrity than LASIK because there is no large hinged flap. LASIK uses microkeratome or femtosecond laser to create a flap followed by excimer ablation. PRK (photorefractive keratectomy) removes the epithelium and performs excimer ablation on Bowman's layer/anterior stroma. Phakic IOL involves lens implantation.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.