Which parameter obtained from partial coherence interferometry (IOLMaster) is most critical for accurate IOL power calculation in post-LASIK eyes?
- A Axial length
- B Anterior chamber depth
- C Keratometry readings ✓
- D White-to-white diameter
Correct answer: C. Keratometry readings
Explanation
In post-LASIK eyes, keratometry readings are the most problematic parameter because standard keratometers and topographers measure anterior corneal curvature and assume a fixed anterior-to-posterior corneal ratio. LASIK flattens the anterior surface without proportionately changing the posterior surface, causing underestimation of true corneal power. This leads to hyperopic surprises. Special formulas (Shammas, Haigis-L, Barrett True K) or historical refraction data must be used to correct keratometry.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.