Background/aims To include intraoperative measurements of the anterior lens capsule of the aphakic eye into the intraocular lens power calculation (IPC) process and to compare the refractive outcome with conventional IPC formulae.

Methods In this prospective study, a prototype operating microscope with an integrated continuous optical coherence tomography (OCT) device (Visante attached to OPMI VISU 200, Carl Zeiss Meditec AG, Germany) was used to measure the anterior lens capsule position after implanting a capsular tension ring (CTR). Optical biometry (intraocular lens (IOL) Master 500) and ACMaster measurements (Carl Zeiss Meditec AG, Germany) were performed before surgery. Autorefraction and subjective refraction were performed 3 months after surgery. Conventional IPC formulae were compared with a new intraoperatively measured anterior chamber depth (ACD) (ACD_IntraOP) partial least squares regression (PLSR) model for prediction of the postoperative refractive outcome.

Results In total, 70 eyes of 70 patients were included. Mean axial eye length (AL) was 23.3 mm (range: 20.6–29.5 mm). Predictive power of the intraoperative measurements was found to be slightly better compared to conventional IOL power calculations. Refractive error dependency on AL for Holladay I, HofferQ, SRK/T, Haigis and ACD_intraOP PLSR was r²=−0.42 (p<0.0001), r²=−0.5 (p<0.0001), r²=−0.34 (p=0.010), r²=−0.28 (p=0.049) and r²<0.001 (p=0.866), respectively,

Conclusions ACD_IntraOP measurements help to better predict the refractive outcome and could be useful, if implemented in fourth-generation IPC formulae.