Association Between Age-Related Cataract and Knee Osteoarthritis: a Comparative and Correlational Study Focusing on Disease Severity

INTRODUCTION: There are several common features between age-related cataract and knee osteoarthritis. Both disorders are associated with serum immunoglobulin E levels, connective tissue growth factor, and oxidative stress. Musculoskeletal disorders have been identified as the most common comorbidities in patients with age-related cataract, with knee osteoarthritis being the most frequent. Therefore, the authors aimed to further investigate this association, considering the severity of these disorders.
METHODS: In this study, data from 350 knee joints and 350 eyes were analyzed. The severity of knee osteoarthritis was assessed radiographically using the Kellgren-Lawrence (KL) grading system. The severity of cataracts was evaluated based on the degree of opacification, using the Lens Opacities Classification System III.
RESULTS: Cataract grades were significantly lower in KL grade 0 compared to other grades for cortical cataract and posterior subcapsular cataract. Additionally, cataract grades were significantly lower in KL grade 1 compared to grades 3 and 4 for posterior subcapsular cataract. There were significant positive correlations between knee osteoarthritis grades and the grades of nuclear cataract (r = 0.121, p = 0.024), cortical cataract (r = 0.137, p = 0.010), and posterior subcapsular cataract (r = 0.215, p = 0.001).
DISCUSSION AND CONCLUSION: There is a significant relationship between age-related cataracts and knee osteoarthritis in terms of disease severity. Beyond their association with aging, these two conditions may share common pathophysiological features. This study may provide new insights into the mechanisms underlying age-related cataracts and knee osteoarthritis.

Keywords: Cataract, knee osteoarthritis, aging, lens opacity, knee joints.