The effects of different shapes of capsulorrhexis on postoperative refractive outcomes and the effective position of the intraocular lens in cataract surgery

BACKGROUND: To evaluate the effects of anterior capsular opening size on deviation from predicted refraction and the effective position of the intraocular lens (ELP) in cataract surgery. METHODS: Nonrandomized clinical trial. Eighty patients (80 eyes) with simple age-related cataracts were treated from May 2018 to September 2018 at the Fourth Affiliated Hospital of China Medical University. All patients undergoing phacoemulsification received intraocular lens based on the voluntary principle. Forty eyes were implanted with the C-loop haptic intraocular lens (AMO Tecnis ZCB00) while the other 40 eyes were implanted with the plate haptic intraocular lens (CT ASPHINA 509 M). Follow-up visits were conducted postoperatively at 1 week, 1 month, and 3 months during which patients underwent refraction and data collection after pupil dilation, which included anterior segment photography and Scheimpflug imaging by Pentacam. The area, horizontal and vertical diameter of the capsulorrhexis, circularity, decentration, and package were analysed using the image analysis software Image-Pro-Plus 6.0,then evaluated the relationship between the different shapes of capsulorrhexis with deviation from predicted refraction and ELP in cataract surgery. RESULTS: Deviation from predicted refraction and all of the parameters of capsulorrhexis were not correlative in the 509 M IOL group, however, in the Tecnis IOL group, while the deviation from predicted refraction and all of the capsulorrhexis parameters were not correlative at 1 week, the deviation from predicted refraction did correlate with capsulorrhexis area, horizontal diameter at 1 month (P = 0.029, P = 0.048), and with capsulorrhexis area, vertical diameter at 3 months (P = 0.03, P = 0.017). The ELP correlated with package in both groups postoperatively (r > 0, P < 0.05), but there is no other capsulorrhexis parameters correlated with ELP in the 509 M IOL group (all P > 0.05). For the Tecnis IOL group, the ELP and capsulorrhexis area were correlated at 1 week and 1 month, while the ELP and horizontal diameter, the ELP and vertical diameter were correlated at 1 week, but did not correlate with the other capsulorrhexis parameters in the Tecnis IOL group (all P > 0.05). CONCLUSIONS: The shape of the capsulorrhexis has an effect on postoperative refractive outcomes and the effective position of the intraocular lens in cataract surgery, and plate haptic intraocular lenses have better refractive stability than C-loop haptic intraocular lenses. TRIAL REGISTRATION: ChiCTR1800015638,2018-04-12.