ObjectiveTo observe the unfolding status of foldable acrylic intraocular lens (IOL) of different materials, designs and refractive powers implanted in the capsular bag during cataract surgery, and to investigate its influence on the IOL implantation procedure.

MethodsAn observational case series study was conducted.A total of 1 005 patients who underwent routine phacoemulsification and IOL implantation in Shaanxi Eye Hospital from February to August 2021 were enrolled.The status and unfolding time of the leading haptic, optical region, and trailing haptic of the IOL in the capsular bag and the surgeon were recorded in real-time intraoperative video.Of the 1 005 IOL implants, 681 were hydrophobic, 324 hydrophilic, 733 C-loop, 272 plate-haptic, 909 single-piece, 96 three-piece, 620 preloaded, and 385 non-preloaded.The differences in unconventional implantation factors and IOL unfolding time were compared.The factors influencing IOL implantation status were analyzed by multivariate logistic regression.Multivariate logistic regression was used to analyze the relevant factors affecting IOL implantation status.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Xi'an People's Hospital (Xi'an Fourth Hospital)(No.20200035). Written informed consent was obtained from each subject.

ResultsThere were 14(1.4%) IOLs with unconventional leading haptic status during implantation, including 7 recurved, 4 folded, 2 twisted and 1 straightened.There were 101(10.0%) IOLs with unconventional trailing haptic status during implantation, including 49 stuck in the injector, 40 folded, 10 recurved and 2 broken.There were 22(2.2%) IOLs with overlapped leading and trailing haptic requiring additional separation.There were 4(0.4%) IOLs with reversed optical regions and 2(0.2%) with damaged optical regions.The occurrence rate of unconventional leading haptic status using C-loop IOL was higher than that using plate IOL, and the difference was statistically significant ( P<0.05). The occurrence rate of unconventional trailing haptic status using hydrophilic, non-preloaded, three-piece, and C-loop IOL was higher than that using hydrophobic, preloaded, single-piece, and plate IOL, respectively, and the differences were statistically significant ( χ ²=9.100, 61.400, 81.885, 7.587; all at P<0.05). The 22(2.2%) IOLs with overlapped leading and trailing haptic were hydrophobic.The 4 (0.4%) IOLs with reversed optical region were non-preloaded.The results of multivariate logistic regression analysis showed that IOL material, loading method, design and surgeons were related to the unconventional trailing haptic status in implantation ( OR=9.894, 3.720, 6.810, 1.338; all at P<0.05). The average unfolding time of hydrophobic IOL was 26.12(21.21, 30.91)s, which was significantly longer than 3.03(2.16, 4.49)s of hydrophilic IOL ( Z=-25.603, P<0.05). The average unfolding time of C-loop IOL was 25.53(19.41, 30.25)s, which was significantly longer than 2.70(2.08, 3.69) s of plate IOL ( Z=-23.764, P<0.05).

ConclusionsA variety of unconventional statuses of IOL can occur during implantation into the lens capsular bag.The use of hydrophobic, preloaded, single-piece, and plate IOLs can reduce the occurrence of unconventional status.The use of hydrophilic IOLs can reduce the overlap of leading and trailing haptic.The use of preloaded IOLs can reduce the occurrence of IOL optical region reversal.The use of hydrophilic and plate IOLs can shorten the operation time.