Ocular geometry-based formula for predicting the intraocular lens position after cataract surgery using anterior segment optical coherence tomography

To devise a new formula for predicting the intraocular lens (IOL) position after cataract surgery using anterior segment optical coherence tomography (AS-OCT) parameters. The IOL position was determined in eyes that had undergone cataract surgery with single-piece acrylic IOLs by a single surgeon. A formula was devised to predict the postoperative IOL position based on four parameters: angle-to-angle (ATA) depth, ATA width, and corneal thickness (measured via AS-OCT), as well as axial length (AL) (measured via the IOL Master 700). These parameters were geometrically combined to derive the diameter of the posterior circle (Dpc) or θ (the angle between the angle-to-angle line and the line connecting the iridocorneal angle to the posterior pole), which were used as predictors in the 29-eye training set. Then the formula was used to predict the postoperative IOL position, and the results were compared with the actual IOL position measured 1 month postoperatively. In the training set, the distance from the anterior surface of the IOL to the posterior pole relative to Dpc (R L/D ) was 89.39% ± 0.66%. A similar ratio was observed in the validation set ( n = 225 eyes, 89.50% ± 0.77%). The postoperative IOL position predicted by the formula was 4.02 ± 0.28 mm, while the actual value was 4.02 ± 0.29 mm (mean prediction error: 0.00 ± 0.14 mm; mean absolute prediction error: 0.11 ± 0.09 mm). A reduced model including θ alone achieved equivalent validation accuracy to the full model (mean absolute prediction error: 0.11 ± 0.09 mm for both models; p = 0.862). We found a regularity in the distance from the anterior surface of the IOL to the posterior pole by assuming a circle that fits the posterior segment of the eyeball and determined a novel formula to predict postoperative IOL position. Further validation in different IOL models and surgical settings is warranted.