A 27-year-old with myopia of -6.0D, corneal thickness 510 µm, and normal topography is being evaluated for refractive surgery. The minimum acceptable residual stromal bed thickness after LASIK to reduce the risk of post-LASIK ectasia is:
- A 200 µm
- B 300 µm ✓
- C 250 µm
- D 350 µm
Correct answer: B. 300 µm
Explanation
The established safe minimum residual stromal bed thickness after LASIK is 250–300 µm; most consensus guidelines recommend ≥300 µm to reduce the risk of post-LASIK ectasia. The tissue ablation rate is approximately 12–14 µm per dioptre of myopia correction. For -6.0D, ablation depth is ~72–84 µm plus flap thickness (~100–130 µm), requiring preoperative corneal thickness of at least 480–510 µm. Any calculation that leaves the RSB <250 µm is a contraindication.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.