The book presents a top-down circuit description for the implementation of asynchronous vision sensors based on Single-Photon Avalanche Diodes (SPADs). It provides design considerations to convey the SPADs pulses through a channel shared by all the pixels. The book also presents architectures where dynamic vision sensors and SPADs converge. Design of Event-Driven SPAD-Based 3D Image Sensors provides detailed technical insights about novel image sensor architectures with SPADs with asynchronous operation. At the sensor level, the book provides asynchronous circuitry to read and arbiter the pixel outputs. The authors explore new LiDAR architectures with asynchronous operation and provide insights into their design. A detailed benchmark of modern and competitive LiDAR systems is also presented. At the pixel level, the book provides design considerations to convey the SPADs pulses through a channel shared by all the pixels. At the sensor level, the book provides asynchronous circuitry to read and arbiter the pixel outputs. Finally, experimental results of very novel LiDAR systems with asynchronous operation will be provided and analyzed. The book is written for professionals who want to explore new tendencies on the design of image sensors for the implementation of LiDAR systems.