Changes in Pupil Diameter and Reactions during the Phacoemulsification Stage with Posterior Chamber Intraocular Lens Implantation

Objective: To investigate changes in pupil diameter and reaction parameters following phacoemulsification with posterior chamber intraocular lens (IOL) implantation. Methods: This prospective study included patients who underwent consecutive cataract and high myopia transparent crystalline lens replacement and were scheduled to undergo phacoemulsification from January to September 2016 in Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine. Pupil diameter under four controlled illumination levels (0, 1, 10, and 100 cd/m2) and reaction parameters (initial diameter, amplitude of contraction, latency of contraction, duration of contraction, velocity of contraction, latency of dilatation, duration of dilatation, and velocity of dilatation) were measured preoperatively and 1 week and 1 month postoperatively using computerized dynamic pupillometry (Metro-vision MONCV3). A Pearson correlation coefficient, Spearman correlation coefficient, and repeated measures analysis of variance were used to analyze the data. Results: In total, 53 eyes from 53 patients were included in this study. Under the four conditions of illumination, pupil diameter decreased as age increased (r0=-0.467, P0<0.001; r1=-0.383, P1=0.005; r10=-0.374, P10=0.006; r100=-0.312, P100=0.023). The overall differences in pupil diameters before and after surgery under 4 kinds of illumination intensity were statistically significant (F0=206.9, P0<0.001; F1=106.8, P1<0.001; F10=41.7, P10<0.001; F100=36.7, P100<0.001). Compared to preoperative measurements, postoperative pupil diameters were reduced at 1 week and 1 month under the four conditions of illumination (P<0.001). The overall differences in the initial diameter and constriction amplitude of pupil reaction were reduced, and the differences in pupil contraction and dilation velocity reaction were statistically significant (Finitial diameter=99.5, Pinitial diameter<0.001; Fcontraction amplitude=36.2, Pcontraction amplitude<0.001; Fcontraction velocity=51.9, Pcontraction velocity<0.001; Fdilation velocity=23.840, Pdilation velocity<0.001). Compared to preoperative measurements, the initial diameter and constriction amplitude of pupil reaction were reduced, and pupil contraction and dilation velocity reaction declined at 1 week and 1 month postoperatively (P<0.001). Conclusions: Pupil diameters are smaller and pupil constriction and dilation velocity are slower within 1 month postoperatively. These data may provide a clinical basis for determining the effective optical range in the design of IOLs. Key words: phacoemulsification; intraocular lenses; pupil diameter; pupil reaction