Study Finds Elevated SII Levels Increase Cataract Prevalence, Suggesting New Path for Prevention

"These findings suggest that SII may be an important biomarker for evaluating cataract risk, highlighting the potential of managing systemic inflammation as an effective strategy for preventing cataracts," the researchers wrote.

The lens, located behind the iris, plays a vital role in focusing light onto the retina. Cataracts reduce lens clarity, impair vision, and affect contrast sensitivity, color perception, and glare. Despite being treatable, cataracts remain a leading cause of global vision loss, with factors such as aging, smoking, diabetes, and UV exposure contributing to their development. Inflammation, particularly systemic immune responses, is increasingly recognized as a key factor in cataract formation.

Given the role of the Systemic Immune-Inflammation Index in inflammatory diseases, Jia-feng Tang, Chongqing Three Gorges Medical College, Wanzhou, Chongqing, China, and colleagues aimed to explore the association between SII and cataract prevalence in adults using NHANES data.

For this purpose, the researchers conducted a cross-sectional analysis using the 2005–2008 NHANES data to investigate the association between SII and cataract prevalence. The study accounted for various covariates, including age, race/ethnicity, gender, education level, marital status, BMI, smoking, alcohol consumption, hypertension, hyperlipidemia, and diabetes.

Multivariable logistic regression assessed the relationship, while spline curve fitting explored non-linear associations. Threshold analysis identified key inflection points. Propensity Score Matching (PSM) was applied to minimize age-related bias, aligning cataract patients with non-cataract individuals. The study analyzed data from 3,623 participants, with 730 (20.15%) diagnosed with cataracts.

The study led to the following findings:

After adjusting for all covariates, multivariable logistic regression showed that higher SII levels were significantly linked to increased odds of cataracts:

• Model 1: OR = 1.56

• Model 2: OR = 1.55

• Model 3: OR = 1.57

• The spline curve fitting model revealed a non-linear relationship between ln-SII and cataract prevalence, with a critical inflection point at an SII of 428.38.

• After Propensity Score Matching (PSM) adjustments, SII levels remained significantly associated with cataract prevalence:

• Model 1: OR = 1.48

• Model 2: OR = 1.48

• Model 3: OR = 1.46

The study, based on NHANES data, reveals a significant link between SII and cataract development. Elevated SII levels, which indicate systemic inflammation, are associated with higher cataract risk. A critical SII threshold of 428.38 is identified, suggesting its potential as a valuable biomarker for assessing cataract risk and enabling early prevention.

"These findings underscore the important role of systemic inflammation in cataract development," the researchers concluded.

Reference:

Li, X., Du, G., Wu, S., Sun, Y., Zhang, S., Zhang, Z., & Tang, J. (2025). Association between systemic immune inflammation index and cataract incidence from 2005 to 2008. Scientific Reports, 15(1), 1-9. https://doi.org/10.1038/s41598-024-84204-7