Blindness affects millions of people around the world, being triggered by various defects within the human visual system. Different kinds of prostheses have been developed, which can stimulate the retina, the optical nerve or even the visual cortex, creating a basic form of vision. Here, we present a scalable ASIC and data-acquisition system that enables neural stimulation and recording in the visual cortex. The ASIC includes 128 area-efficient fully-programmable stimulators and 64 low-noise artifact-tolerant recording channels. The chip has been implemented in a 55nm CMOS technology, and our measurement results demonstrate its ability to stimulate and record simultaneously from the same electrode or from neighboring electrodes, which is important to enable the implementation of visual cortex prostheses.