Association of Cumulative Dissipated Energy With Early Postoperative Corneal Edema Following Phacoemulsification: A Prospective Observational Study

Abstract

Background: Early corneal edema after phacoemulsification reflects postoperative disturbance of corneal hydration and may be associated with intraoperative endothelial stress. Cumulative dissipated energy (CDE) is a device-generated index of ultrasound use. This study examined the association of CDE with day-1 corneal edema, central corneal thickness (CCT) changes, and day-30 endothelial cell loss.

Methods: In this prospective observational cohort, 120 eyes of 120 patients underwent uncomplicated longitudinal phacoemulsification by one surgeon. CDE was recorded intraoperatively; CCT was evaluated before surgery and on postoperative days 1, 7 and 30. Day-1 edema was graded 0–4, with grade ≥2 prespecified as clinically significant; endothelial cell density (ECD) was reassessed on day 30. Associations were evaluated using Spearman correlation, multivariable linear and logistic regression, and receiver operating characteristic (ROC) analysis.

Results: Mean CDE was 8.58 ± 4.33 %-s. Mean CCT increased by 56.7 ± 25.9 µm (10.7%) on day 1 and was close to baseline by day 30. Day-1 CCT increases were 38.2, 52.7 and 79.2 µm across ascending CDE tertiles (p < 0.001). Clinically significant edema occurred in 52 eyes (43.3%): 8/40 (20.0%), 14/40 (35.0%) and 30/40 (75.0%) across tertiles (p < 0.001). CDE correlated with day-1 CCT change (Spearman ρ = 0.71; p < 0.001). After adjustment, each 1 %-s increase in CDE was associated with 4.14 µm greater day-1 CCT change (95% CI 2.91–5.37) and higher odds of grade ≥2 edema (adjusted OR 1.37; 95% CI 1.11–1.70). Lower preoperative ECD was also associated with the primary outcome; diabetes was associated with greater continuous CCT change but not significantly with grade ≥2 edema. Apparent discrimination by CDE was moderate (AUC 0.78; 95% CI 0.69–0.86); the sample-derived 8.4 %-s cut-off yielded 71.2% sensitivity and 73.5% specificity. Higher CDE was associated with greater day-30 endothelial cell loss.

Conclusion: Within this cohort, higher CDE was independently associated with more marked early postoperative corneal swelling and one-month endothelial cell loss. The proposed CDE threshold is exploratory and requires validation before use for individual treatment decisions.

Keywords: cumulative dissipated energy; phacoemulsification; corneal edema; central corneal thickness; corneal endothelial cell density; cataract surgery