Changes in Clotting Time, Plasma Fibrinogen Levels, and Blood Viscosity After Administration of Ranibizumab for Treatment of Choroidal Neovascularization

Abstract

Purpose: To observe changes in clotting time, plasma fibrinogen levels, and blood viscosity after intravitreal ranibizumab (IVR) injection in patients with macular choroidal neovascularization (CNV).Methods: A total of 77 patients were enrolled in the study. Patients were divided into a study group (n = 42 CNV patients) and a control group (n = 35 age- and gender-matched healthy subjects). Study group patients received IVR injections; control group patients received none. Clotting times, plasma fibrinogen levels and blood viscosity were evaluated before, and 1 week and 1 month after the first IVR injection, and again 1 month after the second injection in the study group, but only once in the control group. A paired-sample t-test was used to analyze data at four time points in the study group. Study group patients were further categorized as those with neovascular age-related macular degeneration (AMD subgroup) or CNV secondary to pathological myopia (PM subgroup). Indicators were also analyzed for each subgroup.Results: There were no significant differences between study and control group patients in baseline values. Results showed that 1 week after the first IVR injection, the mean activated partial thromboplastin time (APTT) of study group patients was significantly reduced compared with baseline values (27.88 ± 4.00 versus 30.70 ± 5.56 s), respectively. Low-, median- and high-shear viscosity rates were increased significantly compared with baseline values. No statistically significant changes in tested indicators were found at other time points. In AMD subgroup patients, changes in all indicators were similar to those found overall. In contrast, only changes in median- and high-shear viscosity rates were statistically significant in PM subgroup patients.Conclusion: IVR injection may cause short-term fluctuations in APTT and blood viscosity in AMD patients. Further studies are needed to establish the long-term safety of IVR treatment.