Is There a Safe Glycemic Threshold for Cataract Surgery?

Abstract

Objective: To assess the relationship between cataract surgery and the 30-day incidence of post-operative endophthalmitis (POE) (analysis 1) and serious systemic adverse events (analysis 2) in diabetic patients with varying preoperative hemoglobin A1c (HbA1c) levels.

Design: Retrospective, longitudinal cohort study; multicenter study using a global federated database of electronic health records.

Subjects and controls: Adults (≥18 years) with type 1 or type 2 diabetes mellitus who underwent phacoemulsification cataract surgery. Control groups in analysis 1 were patients without diabetes who underwent cataract surgery. Control groups in analysis 2 were diabetic patients with similar HbA1c who had a routine eye examination without cataract surgery.

Intervention: Cataract surgery.

Main outcomes measures: The primary outcomes were 30-day incidence of: (1) POE, defined by ICD-10 codes; and (2) serious systemic adverse events, including mortality, stroke/transient ischemic attack, major cardiovascular events, and a composite outcome of these events. Hazard ratios (HRs) and 95% CIs were calculated using Cox proportional hazards models.

Results: In analysis 1, the risk of POE within 30 days post-cataract surgery did not differ significantly across HbA1c levels compared to non-diabetic controls. The HRs were 0.62 (95% CI, 0.30-1.27) for good HbA1c level (<7%), 1.08 (95% CI, 0.44-2.66) for moderate (7%-8.4%), 1.36 (95% CI, 0.43-4.28) for poor (8.5%-11.3%), and 2.85 (95% CI, 0.29-27.44) for very poor HbA1c (>11.3%). In analysis 2, the HRs for the 30-day composite outcome of any systemic events were not significantly different across HbA1c levels compared to controls. The 90-day analyses showed similar results for systemic events.

Conclusions: Cataract surgery does not appear to increase the risk of POE or serious systemic adverse events in diabetic patients across all HbA1c levels. These findings suggest that HbA1c alone should not be a reason to defer cataract surgery and highlight the need for individualized risk assessments to determine surgical fitness.