Association of Keratin 8 Level in Aqueous Humor With Outcomes of Intravitreal Ranibizumab Treatment for Neovascular Age-Related Macular Degeneration

PURPOSE: To investigate keratin 8 (KRT8) level in the aqueous humor (AH) of patients with neovascular age-related macular degeneration (nAMD) and elucidate its association with intravitreal ranibizumab (IVR) treatment outcomes. METHODS: This prospective study involved 58 eyes of treatment-naïve nAMD patients treated with three IVR doses monthly and whose AH samples were collected at baseline and two months after the initial treatment. KRT8 level was determined using the enzyme-linked immunosorbent assay and compared with that of the control group, which comprised patients who underwent cataract surgery during the same period. The nAMD-affected eyes were classified into responder (dry) and poor responder (persistent fluid) groups, according to optical coherence tomography (OCT) findings at month three. Additionally, associations between the KRT8 level and IVR treatment outcomes were analyzed. RESULTS: The baseline KRT8 level was significantly higher in the AMD group than in the control group. In the AMD group, responders demonstrated significant differences between the KRT8 level at the baseline and month two, whereas poor responders exhibited no significant change. Regression analysis revealed that a higher KRT8 level at month two was significantly associated with persistent fluid upon OCT at months three and six. CONCLUSIONS: Monitoring aqueous KRT8 level may facilitate early determination of the therapeutic effects of IVR in nAMD patients and reflect the conditions of retinal pigment epithelium during the disease course. TRANSLATIONAL RELEVANCE: Monitoring aqueous KRT8 may aid early determination of therapeutic effects of IVR in neovascular AMD patients and reflect the health conditions of retinal pigment epithelium.