To clarify the mechanism associated with the deterioration of optical cameras in orbit due to radiation, a heavy-ion irradiation test was performed on an 8-transistor (8T) global shutter complementary metal oxide semiconductor (CMOS) image sensor. The experimental results denote that radiation exposure to different functional modules leads to different abnormalities in the resulting images, including forcing the output image to be always zero, the creation of output anomalies in several adjacent column outputs, and the corruption of data over the whole image. Further, the effect of the microcosmic process of the heavy-ion irradiation in the device on the macrocosmic abnormal regions of the resulting images are analyzed for various sub-circuit functions, process structures, and working principles of devices. This analysis provides an overview of the sensitivity and damage mechanism with respect to the different functional modules of the camera sensor. These research results provide significant reference data for the radiation-proofing design of CMOS image sensors, the experimental methods for single-event simulation on the ground, and the establishment of standards and assessment techniques.