Factors impacting cumulative dissipated energy levels and postoperative visual acuity outcome in cataract surgery

Purpose To determine factors impacting cumulative dissipated energy (CDE) and postoperative best-corrected visual acuity (BCVA) in phacoemulsification. Design Review of 1102 cases at University of California, San Francisco (UCSF) and at Zhongshan Ophthalmic Center (ZOC), China. Subjects Patients who underwent cataract surgery at UCSF 03/2014-03/2019 and at ZOC 10/2018-05/2019. Methods Patient demographics, medical history, routine ocular examination, and surgical information, including disassembly method, complications, and surgeon training level were recorded. Univariable and multivariable regression models were used to determine factors associated with CDE and good postoperative BCVA (20/40 or better) at 1 month. Outcome measures CDE, postoperative BCVA. Results In multivariable analysis, patient age at time of surgery, diabetes, degree of nuclear sclerosis (NS), white-to-white corneal diameter, disassembly method, preoperative BCVA, surgeon training level, and surgical center were significantly associated with CDE. Log(10)CDE increased by 0.20-0.31 for patient age >= 70 years, by 0.07 if the patient had diabetes, by 0.12-0.41 for NS grade >= 2, by 0.48 per 10 mm increase in white-to-white corneal diameter, by 0.34-0.47 for disassembly method other than non-stop chop, by 0.16 per unit increase in preoperative logMAR BCVA, and by > 0.09 when phacoemulsification was performed by residents early in their training. Log(10)CDE was 0.33 higher at UCSF than ZOC. In multivariable analysis, worse baseline visual acuity and age above 90 years at time of surgery decreased the odds of good BCVA (OR = 0.26 per unit increase in preoperative logMAR BCVA; OR = 0.12 for age > 90); comorbid retinal issues decreased the odds of good postoperative BCVA (OR = 0.13-0.39); greater anterior chamber depth (ACD) or shorter axial length (AL), increased the odds of good postoperative outcome (OR = 2.64 per 1 mm increase ACD, OR = 0.84 per 1 mm increase AL). Conclusions Cataract grade determined by slit lamp exam and, for the first time, older patient age, were noted to be important predictors of high CDE. CDE was not a risk factor for postoperative BCVA measured at postoperative 1 month. When surgery was performed by trainees under supervision, lower training level was associated with higher CDE, but not with worse postoperative BCVA.