Manual Marking Guidance vs Digital Guidance System–Assisted Capsulorhexis in Phacoemulsification

Importance: Appropriately sized and well-centered capsulorhexis is key for high-quality phacoemulsification cataract surgery and can be achieved with digital-guidance devices. However, such devices are not readily available, warranting the need for a device-free manual auxiliary capsulorhexis technique. Objectives: To determine if manual marking-assisted capsulorhexis (MMAC) is noninferior to a digital guidance-assisted capsulorhexis (DGAC) in capsulorhexis accuracy following phacoemulsification for age-related cataract. Design, Setting, and Participants: This noninferiority randomized clinical trial was conducted between July 2021 and December 2021 at Zhongshan Ophthalmic Center, China, with follow-up through 1 month after surgery. Of 204 adults screened, 156 were included who were aged 55 to 80 years and had pupil diameter ≥6.5 mm after pupil dilation and Lens Opacities Classification System III with nuclear opalescence grade of 3.0 to 4.0. Patients were excluded if they had previous intraocular surgery or a diagnosed eye disease that might affect functions of lens suspensory ligament. Data were analyzed from September to December 2024. Interventions: In the MMAC group, a lens caliper was used to measure and locate capsulorhexis position, subsequently applying its blunt head to mark the anterior lens capsule for capsulotomy guidance. In the DGAC group, a ring with predefined target diameter was projected to guide capsulorhexis. Main Outcomes and Measures: The primary outcome was the median deviation of capsulorhexis diameter from the target diameter with a noninferiority margin of 0.2 mm. Secondary outcomes included ratio of ideal capsulorhexis, grades of capsulorhexis-intraocular lens (IOL) overlap, off-center distance of capsulorhexis, postoperative best-corrected visual acuity, IOL tilt, and decentration. Results: Among 156 participants randomized into the MMAC group (mean [SD] age, 71 [7] years; 47 [60%] female) or DGAC group (mean [SD] age, 72 [7]; 47 [60%] female), median deviations comparing the capsulorhexis and target diameters were 0.22 mm (95% CI, 0.11-0.37) in the MMAC group vs 0.27 mm (95% CI, 0.14-0.52) in the DGAC group (difference, -0.05 mm; 95% CI, -0.16 to 0.07) for horizontal diameter and 0.27 mm (95% CI, 0.12-0.40) vs 0.33 mm (95% CI, 0.20-0.51) (difference, -0.06 mm; 95% CI, -0.17 to 0.05), respectively, for vertical diameters, both within the noninferiority margin of 0.20 mm. The proportion of ideal capsulorhexis was 96.2% (75 of 78) in the MMAC group and 88.5% (69 of 78) in the DGAC group (difference, 7.7%; 95% CI, -0.6 to 16.0), also within the noninferiority margin of -5.0%. Conclusions and Relevance: The findings in this trial indicate that accuracy of capsulorhexis with MMAC was noninferior to DGAC. Since the MMAC technique does not require special equipment, it might be considered routinely in clinical practice settings if similar outcomes are obtained elsewhere. Trial Registration: ClinicalTrials.gov Identifier: NCT04977115.