Optical Coherence Tomography for IOL Power Calculation in Eyes With Prior Radial Keratotomy
Narrative Responses:
Purpose
In eyes with prior radial keratotomy (RK), to evaluate the accuracy of IOL power calculation using optical coherence tomography (OCT, RTVue) and compare these results to five devices using the ASCRS calculator.
Methods
Consecutive patients with prior RK who underwent cataract extraction with IOL implantation were included. Preoperatively, the OCT was used to measure anterior and posterior corneal powers and pachymetry. Axial length and anterior chamber depth were measured using partial coherence interferometry (IOLMaster). The first cohort of 26 cases was used to develop the OCT-based formula for calculating IOL power in RK eyes. The second cohort of 8 cases was used to validate the formula. The IOL power prediction errors (Implanted – Predicted) were calculated in the validation group using the OCT formula and compared to five devices using the ASCRS calculator.
Results
In the validation group, the mean IOL power prediction errors ranged from -2.10 to +1.05 D using the EyeSys, Atlas, Galilei, IOLMaster and Lenstar, compared to +0.36 D using the OCT. The standard deviation values ranged from 1.67 to 3.29 D for these 5 devices, compared to 1.11 D for the OCT (P<0.05 compared to these 5 devices). More eyes will be added to the validation group, and an updated OCT-based IOL formula for RK eyes will be presented.
Conclusion
The OCT-based IOL power calculation is a promising option for calculating IOL power in post-RK eyes.