The SRK/T formula for IOL power calculation performs WORST in which corneal condition?

• A Post-LASIK/PRK corneas ✓
• B High myopia (axial length >26 mm)
• C High hypermetropia (axial length <22 mm)
• D Keratoconus

Explanation

SRK/T and all standard keratometry-based IOL formulas perform poorly after corneal refractive surgery (LASIK/PRK) because they rely on standard keratometry readings that do not accurately capture the altered posterior corneal curvature. Post-LASIK corneas have a flatter anterior surface but the posterior curvature remains relatively unchanged, violating the fixed anterior-to-posterior radius ratio (1.21) assumed in standard keratometry. The result is hyperopic refractive surprise. The Barrett True-K, Haigis-L, and Shammas-PL formulas, along with the ASCRS post-refractive calculator, are recommended for these cases.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.