Effect of Intracameral Air Injection on Corneal Endothelial Cell Loss After Phacoemulsification for Cataracts of LOCS III Nuclear Grade 4 or Higher: A Randomised Clinical Trial

BACKGROUND: To evaluate the effect of intracameral air injection on corneal endothelial cells in patients undergoing phacoemulsification for cataracts with LOCS III nuclear grade 4 or higher. METHODS: A prospective randomised clinical trial. Patients with cataracts of LOCS III nuclear grade 4 or higher were recruited from Sichuan Provincial People's Hospital between October 2024 and March 2025. Patients were randomised 1:1 to the intracameral air injection group (study group) or the conventional group (control group). Corneal endothelial parameters were assessed at 1 week and 1 month postoperatively. RESULTS: Eighty eyes from 80 patients (mean [SD] age, 68.9 [8.4] years; 43 females [53.8%]) were randomised to the study group (40 [50.0%]) or the control group (40 [50.0%]), with 34 eyes (85.0%) and 35 eyes (87.5%) completing the 1-month follow-up. Postoperative endothelial cell loss (ECL) in the study group was significantly lower than in the control group at 1 week (mean [SD], 6.90% [3.23%] vs. 12.81% [6.32%]; difference, -5.90%; 95% CI, -8.15% to -3.66%; p < 0.001) and at 1 month (mean [SD], 8.15% [3.84%] vs. 15.97% [6.11%]; difference, -7.82%; 95% CI, -10.10% to -5.55%; p < 0.001). For the secondary outcome, the study group showed a smaller increase in central corneal thickness (CCT) than the control group at 1 week (p = 0.02). CONCLUSIONS: Intracameral air injection was associated with lower ECL after phacoemulsification in cataracts with LOCS III nuclear grade 4 or higher. The smaller increase in CCT also suggested a potential benefit for early postoperative corneal recovery. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT06636279.