Repeated inciting events, particularly those involving trauma, are significantly associated with increased risk of developing sympathetic ophthalmia (SO), according to a study published in Ophthalmology. According to the retrospective cohort study, trauma is four to five times more likely to generate SO than vitrectomy. 

The research reports that penetrating trauma has traditionally been considered the principal risk factor for SO. However, prior studies have suggested that intraocular surgeries, especially vitrectomy, have a higher risk for inducing SO than penetrating trauma. To clarify these findings, investigators analyzed the incidence of SO after eye trauma or intraocular surgery, using a nationwide administrative claims database in Japan. 

They utilized the Kaplan-Meier approach to calculate the cumulative incidence of SO after inciting events, stratified by sex, 10-year age groups, and the “primary/repeated”  variable which reflected the history of inciting events in the previous year. The cox regression model estimated the adjusted hazard ratio (aHR) for develping SO, in which sex, age, and the “primary/repeated’ variable were explanatory variables. The investigation limited the study population to patients who only had a single inciting event during the observation period to explore the pure influence of each inciting event. 


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In total, 704,717 patients and 888,041 inciting events met the eligibility criteria. Females represented 46% (n=325,243) of patients, and the 70-79 year age group represented the largest proportion of patients (n=206,868 [29%]). The surgery performed most frequently was vitrectomy (n=364,786 [66%]), followed by trabeculectomy (n=37,118 [7%]). The total number of SO cases was 263 and the overall cumulative incidence of SO in all eligible patients was 0.044% over 60 months.

Sex was not significantly associated with SO development (aHR, 1.01 [95% confidence interval, 0.79-1.29]; P =.95). The 40-49 year age group had the highest cumulative incidence of SO for most of the entire period, with a cumulative incidence of 0.104% over 60 months. Repeated inciting events with and without trauma had higher incidences of SO (0.47% and 0.072%; aHR vs primary inciting events, 11.68 [7.74-17.64] and 2.21 [1.59-3.07]) compared with primary inciting events (0.036%). 

The incidence of SO at 60 months was notably higher after trauma (0.073%) than after vitrectomy (0.016%). According to investigators, the incidence of SO at 60 months was lowest after scleral buckling.

Researchers note several limitations to their work, including the possibility of misclassification bias due to the laterality of the eyes not being recorded in the database. Additionally, cataract surgery was not included as exposure. Lastly, most of the study population consisted of Japanese patients, which may preclude these findings from being generalizable to other ethnic groups. 

Based on data from the present study, trauma significantly increased the risk of SO compared with vitrectomy. 

Reference

Hashimoto Y, Matsui H, Michihata N, et al. Incidence of sympathetic ophthalmia after inciting events: a national database study in Japan. Ophthalmol. Published online September 20, 2021. doi:10.1016/j.ophtha.2021.09.011