Dynamic assessment of variations in pupil diameter using swept-source anterior segment optical coherence tomography after phakic collamer lens implantation

Purpose To dynamically assess variations in pupil diameter induced by changes in brightness in myopic eyes implanted with an implantable collamer lens (ICL, STAAR Surgical) with a central port. Methods This prospective, observational single-center case series study comprised 65 eyes from 65 consecutive patients undergoing ICL implant. A modified commercially available swept-source Fourier-domain anterior segment optical coherence tomography (AS-OCT) device was used for imaging and performing dynamic pupillometry under changing light conditions before and after a mean follow-up interval of four months after surgery. Results Preoperative mean pupil size under photopic conditions was 3.38 +/- 0.64 mm; after surgery, this increased to 3.48 +/- 0.61 mm. Mean pupil size under scotopic light conditions was 5.72 +/- 0.79 mm before surgery and 5.84 +/- 0.77 mm postoperatively. The differences between preoperative and postoperative pupil diameter in miosis and mydriasis were 0.10 +/- 0.44 mm (P = 0.078) and 0.12 +/- 0.58 mm (P = 0.098), respectively. The scotopic pupil exceeded the optic zone of the implanted lens in 39 eyes (60%). The mean central vault value was 412 +/- 177 mu m under maximum miosis and 506 +/- 190 mu m under maximum mydriasis. We found a positive correlation between vault and differences in pupil diameter under all light conditions (P < 0.05). Conclusion Dynamic AS-OCT enables a very precise determination of the pupillary diameter in the iris plane. The changes in the pupil diameter under different light conditions after the implantation of an ICL are related to the postoperative vault.