The sense of equilibrium aggregates several interacting cues. On vestibular areflexic patients, vision plays a major role. We developed an immersive therapeutic platform, based on 3D opto-kinetic stimulation that enables to tune the difficulty of the balance task by managing the type of optic flow and its speed. The balance adjustments are recorded by a force plate, quantified by the length of the center of pressure trajectory and detection of disequilibrium corrections (leans, compensation step). Preliminary analysis shows that (i) patients report a strong immersion feeling in the motion flow, triggering intense motor response to "fight against fall"; (ii) the ANOVA factorial design shows a significant effect of flow speed, session number and gaze anchor impact. In conclusion, this study shows that 3D immersive stimulation removes essential limits of traditional opto-kinetic stimulators (limited 2D motions and remaining fixed background cues). Moreover, the immersive optic flow stimulation is an efficient tool to induce balance adaptive reactions in vestibular patients. Hence, such a platform appears to be a powerful therapeutic tool for training and relearning of balance control processes.