Visual capabilities recovery for some kind of illness is possible through subretinal implantable device stimulation. Two possible architectures for retinal pixel are proposed, fabricated in 0.35mum CMOS and compared, including evaluation of electronic response on a human-tissue-like interface. In these solutions, power consumption has been proved to be dominated by electrode stimulation and, in normal light condition, typical consumption is below 1 mW/pixel. The proposed pixel architectures, with 120 mum (LICOS) and 100 mum (WATCH) inter-pixel step, provide the smallest, standalone, subretinal implantable chips ever reported.