Which corneal refractive surgery technique results in a corneal flap created at a stromal depth of approximately 160 microns, with preservation of Bowman's layer entirely?

• A LASIK with a mechanical microkeratome
• B SMILE (Small Incision Lenticule Extraction) ✓
• C LASEK (Laser epithelial keratomileusis)
• D DALK (Deep Anterior Lamellar Keratoplasty)

Explanation

SMILE uses a femtosecond laser to create a refractive lenticule within the stroma (at approximately 120-160 microns depth) through a small 2-4 mm incision, extracting it without creating a flap and without ablating tissue with excimer laser. Because no flap is created, Bowman's layer is only minimally disrupted (at the small extraction incision site), resulting in better biomechanical stability compared to LASIK. LASEK preserves Bowman's layer by displacing only the epithelial sheet but uses excimer ablation. DALK is used for keratoconus/stromal disease, not refractive surgery for myopia.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.