The aim of this study is to evaluate the changes of pupil diameter and dynamics in patients with different ametropia after implantable collamer lens (ICL)V4c without viscoelastic agent.

A Total of 53 patients (104 eyes) who underwent ICL V4c implantation surgery in the Department of Ophthalmology, Anzhen Hospital in Beijing, China from August 2019 to January 2021 were collected. Among them, there were 11 males (22 eyes) and 42 females (84 eyes) with the average age of (33.5±6.9) years old (ranged from 21 to 48) years old. According to the preoperative equivalent spherical refractive index of patients, they are divided into moderate to low myopia group and high myopia group. The patient's intraocular pressure, equivalent spherical lens, anterior chamber depth, central corneal thickness, and white to white diameter, the pupil diameter before and one month after ICL V4c implantation were performed. Age, intraocular pressure, pupil diameter, and changes in pupil motility and other quantitative data have undergone normality tests and conformed to a normal distribution, were expressed as ±s, and compared by independent sample t-tests for inter group, and paired t-tests for intra group. Quantitative data with equivalent spherical mirrors that did not follow a normal distribution were expressed as median (interquartile range), and compared by Mann Whitney U test for inter group, and Wilcoxon signed rank test for intra group. Gender was expressed in examples and percentages, and compared by χ² for inter group. The correlation analysis between preoperative and postoperative changes in pupil dynamics between two groups was performed using Pearson or Spearman correlation analysis.

Under bright light, the preoperative and postoperative pupil diameters of patients in moderate to low degree myopia group were (4.16±0.60) mm and (3.99±0.65) mm, respectively, with a statistical significance difference between them (t=2.338, P<0.05). Under dark light, the preoperative and postoperative pupil diameters were 5.76 (1.58) mm and 5.48 (1.13) mm, respectively, with no statistically significant difference (Z=1.873, P>0.05). The pupil diameter of moderate to low degree myopia group significantly decreased under postoperative bright light. The preoperative and postoperative pupil diameter of the high myopia group was 4.18 (1.00) mm and 4.17 (1.08) mm, respectively. The differencewas statistically significant between the two groups (Z=2.978, P<0.05). The pupil diameters of the highly myopic group before and after surgery under bright light were 4.18 (1.00) mm and 4.17 (1.08) mm, respectively, with no statistically significant difference (t=-1.004, P>0.05). Under dark light, the preoperative and postoperative pupil diameters were (5.81±0.84) mm and (5.86±0.89) mm, respectively. There was no statistically significant difference in preoperative pupil diameter between the two groups (Z=-1.510, -2.030; P>0.05). Under bright light, the difference in postoperative pupil diameter between the two groups was statistically significant (Z=-0.688, P<0.05). Under dark light, the postoperative pupil diameter was statistically significant (t=-0.02, P<0.05). The difference in pupil diameter dynamics before and after surgery was 1.29 (1.07) mm and (1.48±0.33) mm in the moderate to low degree myopia group, respectively, and there was no statistically significant difference between them (Z=-0.111, P>0.05). The difference in pupil dynamics before and after surgery in the high myopia group was (1.39±0.45) mm, and (1.59±0.53) mm, with a statistical significance difference (t=-3.265, P<0.05). The postoperative changes in pupil dynamics in the high myopia group were significantly larger than that of before surgery. The difference in pupil diameter between the two groups before and after surgery was not statistically significant (Z=-0.306, -0.721; P>0.05). Under bright light, the difference between the postoperative and preoperative pupil diameter in the medium to low degree myopia group was (-0.17±0.48) mm, and under dark light that was -0.09 (0.25) mm, both showing a decreasing trend, with no statistically significant difference (Z=0.000, P>0.05). Under bright light, the difference in postoperative and preoperative pupil diameter in the high myopia group was -0.17 (0.43) mm, and under dark that was (0.05±0.41) mm with statistically significant between them (Z=2.411, P<0.05). The high myopia group showed an increasing trend in postoperative pupil diameter under dark. Spearman correlation analysis showed a positive correlation between the preoperative and the postoperative pupil dynamics with statistical significance in low degree myopia group (r=0.587, P<0.05). Pearson correlation analysis showed a positive correlation between the preoperative and postoperative pupil dynamics, with a statistical significance difference between them (r=0.518, P<0.05).

The pupil diameter of the patients with moderate to low myopia and high myopia can be significantly reduced after ICL V4c implantation for one month without viscoviscoid-assisted implantation under bright light. In patients with high myopia, the pupil diameter changes more greatly under light and dark lighting after surgery, which is more likely to affect the visual quality.