Incidence of Incision-Related Descemet Membrane Detachment Using Phacoemulsification With Trapezoid vs Conventional 2.2-mm Clear Corneal Incision

The conventional 2.2-mm clear corneal incision is relatively narrow compared with the sleeves of Phaco handpieces, resulting in friction at the incision site and increased risk of incision-related Descemet membrane detachment (DMD). The modified 2.2-mm incision only enlarged internal width to 3.0 mm, forming a trapezoid incision shape, which may reduce the friction of surgical instruments and decrease the risk of incisional DMD.To compare the incidence of incision-related DMD between eyes undergoing modified vs conventional 2.2-mm incision phacoemulsification for hard nuclear age-related cataract.This double-masked, parallel randomized clinical trial was conducted from July 22, 2019, to January 22, 2020, at Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China. The study included patients with age-related cataract and nuclear opalescence grade of 4.0 or greater based on the Lens Opacities Classification System III. Patients were enrolled in this study according to the following inclusion criteria: (1) age between 65 to 90 years; (2) pupil size of 6 mm or greater after dilation; (3) Lens Opacities Classification System III nuclear opalescence grade of 4.0 or more; and (4) corneal endothelial cell density greater than 1500 cells/mm2.Modified (enlarged internal width to 3.0 mm) or conventional 2.2-mm incision phacoemulsification with intraocular lens implantation.Incidence of incision-related DMD at postoperative day 1.A total of 130 eyes of 130 patients were randomized into the conventional group (n = 65) or the modified group (n = 65). The mean (SD) age of participants was 74.5 (5.9) years and 74.3 (6.0) years in the conventional and modified groups, respectively. A total of 26 participants in the conventional group (40%) and 27 in the modified group (42%) were men. Compared with eyes in the conventional group, the incidence of DMD in eyes in the modified group was significantly lower at postoperative day 1 (difference, 26.15; 95% CI, 9.60-42.71; P = .003). The difference at postoperative day 7 was 16.92 (95% CI, 2.91-30.94; P = .02). The length of DMD (postoperative day 1: difference, 0.188; 95% CI, 0.075-0.301; P = .002) and maximal corneal thickness at incision site (postoperative day 1: difference, 0.032; 95% CI, 0.006-0.057; P = .02; postoperative day 7: difference, 0.019; 95% CI, 0.003-0.035; P = .02) were lower in the modified group, while visual quality parameter modulation transfer function (postoperative day 1: difference, -0.033; 95% CI, -0.064 to -0.001; P = .04) was higher. No difference was observed between the 2 groups in best-corrected visual acuity, central corneal endothelium loss, or surgically induced astigmatism at any follow-up time. There were no intraoperative complications in the 2 groups.These findings suggest that modified 2.2-mm trapezoid incision phacoemulsification reduces the incidence of DMD for hard nuclear age-related cataract at postoperative day 1 and might be considered in patients at high risk of incision-related DMD, although the clinical relevance cannot be determined with certainty from this trial.ClinicalTrials.gov identifier: NCT04014699.