Cataract surgery may raise the risk of NAION

This study assessed the risk of developing nonarteritic anterior ischemic optic neuropathy (NAION) after cataract surgery.

Study design

The authors conducted a large nationwide, population-based study using the Korean National Health Insurance Service database. The 12-year study included more than 1 million beneficiaries. Among 400,974 eligible individuals, 40,356 underwent cataract surgery and 1,097 were diagnosed with NAION.

Outcomes

The risk of NAION was higher after cataract surgery (HR 2.57) and remained significant (HR 1.75) when compared with matched controls without cataract surgery, even after adjusting for demographics and comorbidities.

The 10-year incidence probability of NAION among the cataract surgery group was 0.70% compared with 0.27% in the control group. The mean interval between cataract surgery and NAION was 807 days (range 1–2,951 days). Among the 139 patients who developed NAION after surgery, only 12 occurred within 3 days after cataract surgery and 5 occurred between 4 days and 3 months; 78% developed NAION more than a year after the procedure.

Limitations

The diagnosis of NAION could not be confirmed with the clinical records, which is an inherent limitation of analyses involving big data sets. Dependence on diagnosis codes also made it difficult to ascertain whether the fellow eye developed NAION. In addition, some variables that could influence the development NAION were not available, such as cup-to-disc ratio, metabolic profile and smoking.

Clinical significance

To date, this is the largest population-based study examining the potential connection between NAION and cataract surgery. The elevated risk of NAION after cataract surgery suggests a causal relationship. However, it remains unclear why the majority of NAION cases were delayed for more than a year after cataract surgery. The reason for this delay may need to be clarified before definitively concluding that cataract surgery is associated with a risk of NAION.