Background <p>Thyroid eye disease (TED) is an autoimmune orbital disorder characterized by fibroblast activation, myofibroblast differentiation, and excessive extracellular matrix production. RhoA/ROCK signaling is increasingly implicated in these fibrotic processes. This study aimed to investigate the effects of the Rho-associated protein kinase (ROCK) inhibitor netarsudil on the expression of fibrogenesis-related genes in orbital fibroblasts derived from patients with TED.</p> Methods and results <p>Primary orbital fibroblasts were isolated from two patients with TED. Cells were treated with varying concentrations of netarsudil (ranging from 2 × 10^− 2 to 2 × 10^− 8 mg/mL). Gene expression of fibrogenesis markers, including <i>TGF-β</i>, <i>α-SMA</i>, <i>ZEB1</i>, <i>Snail</i>, <i>Thy-1</i>, and <i>β-catenin</i>, was assessed via quantitative real-time PCR. Our results demonstrated that netarsudil treatment at non-cytotoxic concentrations not only did not significantly suppress the mRNA expression of the examined fibrogenic markers, but also upregulated the expression of <i>TGF-β</i>, <i>α-SMA</i>, and <i>ZEB1</i>. Higher concentrations of netarsudil appeared to reduce cell viability, suggesting that apparent antifibrotic effects at elevated doses may be secondary to cytotoxicity rather than pathway-specific transcriptional repression.</p> Conclusions <p>Our findings suggest that non-cytotoxic dose of netarsudil, is insufficient to reverse the constitutively pro-fibrotic transcriptional program in TED orbital fibroblasts. The lack of direct antifibrotic efficacy highlights the complexity of TED fibrogenesis and suggests that redundant or parallel signaling pathways may limit the impact of isolated ROCK inhibition. Further research is required to evaluate combination therapies or alternative targets in TED-related fibrosis.</p>