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Published on: September 16, 2025
Comparative Evaluation of Intraocular Lens Power Calculation Formulas in Patients After Radial Keratotomy
Enjie Li1, Zhenyu Wang1, Yangfan Yu1
1Beijing Tongren Eye Center, Beijing Tongren Hospital, Beijing Ophthalmology and Visual Science Key Lab, Capital Medical University, Beijing, China.
Objective:
This study assessing the performance of five intraocular lens (IOL) calculation methodologies in cataract patients with previous radial keratotomy (RK) history.
Methods:
Five formulas predicted refractive outcomes, with prediction errors (PE) calculated by comparing formula-derived spherical equivalents to manifest refraction. Additional statistical analysis examined correlations between formula-specific PE and biometric parameters including axial length (AL) and corneal curvature.
Results:
Overall, Barrett True-K and Hoffer QST showed minimal prediction bias (PE: -0.06D and -0.07D; p > 0.05). PEARL-DGS had the best stability (SD: 0.97) and led in ±0.25D accuracy (20.8%, p = 0.665). In AL subgroups, Barrett True-K showed superior accuracy for medium-long eyes (26.0-30.0 mm; PE closest to zero), while EVO 2.0 yielded significant hyperopic error in short AL eyes (<26.0 mm). Significant negative correlations between flat keratometry and PE were identified for the Hoffer QST, Kane, and Pearl DGS formulas (all p < 0.01). In eyes with flat keratometry < 39.0 D, EVO 2.0, Kane, and Pearl DGS exhibited statistically significant hyperopic biases, while Barrett True-K and Hoffer QST maintained accuracy without systematic error.
Conclusion:
The results indicate that for post-RK patients, the Barrett True-K formula exhibits enhanced accuracy in IOL power calculation. Newer AI-based formulas show potential but currently remain limited by a systematic hyperopic bias in this population.
