Risk factors for endophthalmitis after cataract surgery in diabetic patients: a case control study

To identify risk factors associated with post-cataract surgery endophthalmitis (PCE) in type 2 diabetic patients.

A hospital-based retrospective case-control study was conducted on 194 type 2 diabetic patients undergoing cataract surgery in Rajavithi Hospital from January 2007 to December 2015. Fifteen patients with PCE were included as the case group and 179 patients without PCE were included as the control group. Potential factors associated with PCE among both groups including demographics, pre-operative characteristics, surgical settings and complications, were statistically analyzed using Chi-square testing and a logistic regression model.

Within the case group, 53% were females and the median age was 68y. Univariate analysis of pre-operative characteristics, surgical settings and complications revealed that recent pre-operative fasting plasma glucose, insulin therapy, presence of diabetic retinopathy, and severe non-proliferative or proliferative diabetic retinopathy were significantly associated with PCE. In a multivariate analysis adjusting for blood glucose level, insulin treatment was the only significant factor associated with an increased risk of PCE (OR 3.9, 95%CI 1.0-15.0, P=0.04) compared to patients without insulin treatment. The most common causative organisms were gram-positive bacteria (89%). Staphylococcus species represented the most common group (67%). Median best corrected visual acuity at 1-month and 3-month follow-up was equal at 0.7 logMAR (20/100).

The authors identify insulin treatment as the only risk factor associated with endophthalmitis after cataract surgery in type 2 diabetic patients. Further studies with serum levels of pre-operative glycated hemoglobin (HbA_1c) and post-operative fasting plasma glucose level are essential to truly demonstrate the role of peri-operative glycemic markers as a risk factor for PCE.