Refractive Outcomes and Ocular Biometry of Two Swept-Source Optical Coherence Tomography-Based Biometers With Segmental or Equivalent Refractive Indices (ORION)

This prospective, single-centre, randomized, parallel-group comparative clinical study evaluated the refractive prediction accuracy of two swept-source optical coherence tomography (SS-OCT) biometers in a Thai cataract surgery cohort. The ARGOS biometer applies segmental refractive indices to individual ocular segments, whereas the IOLMaster 700 applies an equivalent refractive index to the whole eye. Each device is conventionally paired with a different keratometry-formula combination: ARGOS with the standard Barrett Universal II (Barrett UII K), and IOLMaster 700 with the Barrett Universal II using total keratometry (Barrett UII TK). The study compared these two device-formula pairings as they are used in routine clinical practice. Both biometers were performed on every eye on the same day, enabling a within-subject paired comparison of biometric agreement and refractive prediction error at one month after phacoemulsification cataract surgery with implantation of a TECNIS Monofocal one-piece IOL (model GCB00V)