Longer the duration of HRT in women greater the risk of nonarteritic anterior ischemic optic neuropathy

Non-arteritic anterior ischemic optic neuropathy (NAION) is a condition caused due to impaired circulation of blood to the front of the optic nerve. It is called “non-arteritic” because there is reduced blood flow without true inflammation of the blood vessels. Women undergoing hormone replacement therapy (HRT) are often presented with several side effects, including vision loss and NAION.

The current epidemiological study in Graefe's Archive for Clinical and Experimental Ophthalmology aimed to assess the association between and the prevalence of nonarteritic anterior ischemic optic neuropathy (NAION) in menopausal women using national data from the entire Korean population.

Study suggests that the use of HRT may be associated with a higher incidence of NAION, which may be important for patient counseling and surveillance. Patients in the non-HRT group were more likely to have diabetes, hypertension, and dyslipidemia as vasculopathic risk factors. The incidence of NAION in the HRT group was approximately 1.268 times higher than that in the non-HRT group; the incidence also increased with the duration of HRT. HRT use in women aged ≥65 years was significantly higher than in those aged <65 years. The hazard ratio of NAION development with at least 5 years of HRT was 1.473.

The researchers conducted health screening data of 1,381,605 women between 40 and 90 years of age collected by the National Health Insurance Service (NHIS) of Korea between January 1, 2009, and December 31, 2018, were retrospectively reviewed. Before data analysis, the potential cofounders were adjusted for among all participants. Based on HRT use and its duration (classified into four groups), the hazard ratio (HR) and 95% confidence interval (CI) of NAION development were calculated via a Cox proportional hazards regression analysis using the nonuser group as a reference.

The key findings of the study are

• Overall, 7824 NAION diagnoses were made during the mean follow-up of 8.22 years (standard deviation: 1.09 years) in 1,381,605 post-menopausal women.

• NAION was more common in the HRT group than in the non-HRT group (HR [95% CI]: 1.268 [1.197–1.344]).

• Furthermore, the risk of NAION increased along with increased HRT duration (p < 0.0001). In the multivariate analysis, the adjusted HRs of the < 2-year HRT group, the 2–5-year HRT group, and the ≥ 5-year HRT group were 1.19 (95% CI: 1.10–1.28), 1.3 (95% CI: 1.17–1.45), and 1.473 (95% CI: 1.31–1.65), respectively.

• Compared to women younger than 65 years, the HR of HRT for NAION was significantly higher than that of women older than 65 years (p < 0.0001).

Researchers concluded that “Our population-based cohort study found that HRT was significantly associated with increased incidence of NAION. The incidence of NAION also increased with the duration of HRT.”

Reference: Lee, C., Han, KD., Yoo, J. et al. Hormone Replacement Therapy and the Incidence of Nonarteritic Anterior Ischemic Optic Neuropathy: a Nationwide Population-Based Study (2009–2018). Graefes Arch Clin Exp Ophthalmol 261, 2019–2029 (2023). https://doi.org/10.1007/s00417-023-05976-8