A 40-year-old who underwent uncomplicated LASIK 8 years ago now needs cataract surgery. Corneal topography confirms prior myopic ablation. Which approach gives the most accurate IOL power calculation?
- A Use standard keratometry values in the SRK/T formula
- B Add 1 D to the SRK/T result to compensate for flat keratometry
- C Use the Haigis-L formula designed for post-corneal refractive surgery eyes ✓
- D Use contact lens over-refraction with the Hoffer Q formula using pre-LASIK data only
Correct answer: C. Use the Haigis-L formula designed for post-corneal refractive surgery eyes
Explanation
After myopic laser ablation, standard keratometers underestimate corneal power because they measure the anterior surface with a fixed index of refraction and sample a paracentral zone, leading to postoperative hyperopic surprise. The Haigis-L formula was specifically developed and validated for eyes after myopic LASIK or PRK. Arbitrary addition of dioptres is unreliable, and pre-LASIK-only methods require historical data the surgeon may lack.
Reference: AAO Basic and Clinical Science Course, Lens and Cataract Section 11, 2023-2024 ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.