A randomized controlled clinical study on reverse-chopper prechop technique with phaco-and-chop technique for high myopia associated with hard nucleus cataract

Abstract

Background The innovation of pre-chop technique lies in shortening surgery duration, reducing ultrasound power, and deseasing the loss of corneal endothelial cells (CECs). Objective This study was to compare the efficacy and safety of pre-chop technique using a reverse-chopper and phaco-and-chop phaco technique to super high myopia associated with hard nucleus cataract. Methods A prospective randomized-controlled-clinical interventional study was performed.Fourty eyes of 40 high myopia associated with cataract patients with Ⅲ-Ⅳ degree of nucleus were enrolled in Beijing Tongren Hospital from March to September 2016.The patients were randomized into the pre-chop group and matched phaco-and-chop group according to random number table, and the self-made reverse chopper-assisted pre-chop phacoemulsification (phaco) surgery and phaco-and-chop phaco surgery were performed on the eyes of different groups, respectively.The phaco power, effective phaco duration and best corrected visual acuity (BCVA) were recorded and compared between the two groups to evaluate the efficacy, and the loss rate of corneal endothelial cells and eyes in different grades of cornea edema after operation were compared between the two groups to assess the safety of surgery procedure.Written informed consent from each patient was obtained prior to relevant examination and surgery. Results The surgery was finished smoothly in the eyes.The mean effective phaco duration was (47.30±11.29) seconds and (57.70±14.51) seconds in the pre-chop group and phaco-and-chop group, respectively, with a significant difference between them (t=-2.530, P=0.016). The BCVA was better at the seventh day after surgery in the pre-chop group than that in the phaco-and-chop group (4.75±0.11 vs.4.67±0.14), showing a significant difference between the two groups (t=2.147, P=0.038). In 1 month after surgery, the CECs loss rate was (10.82±3.77)% in the pre-chop group, which was lower than (16.11±6.47)% in the phaco-and-chop group (t=-3.758, P=0.001). The number of the eyes with grade 2-3 of corneal edema in the pre-chop group was significantly decreased in comparison with the phaco-and-chop group 7 days after surgery (Z=11.822, P=0.008). Conclusions Compared with the conventional phaco-and-chop technique, reverse-chopper prechop technique appears to have a better efficacy and safety in phaco surgery for high-myopia associated with hard nuclear cataractous eyes. Key words: Cataract extraction/methods; Phacoemulsification/methods; High myopia; Lens nucleus, crystalline/surgery; Treatment outcome; Pre-chopping technique; Phaco-and-chop technique; Randomized-controlled clinical study; Reverse-chopper