The present invention relates to the design and implementation of a three stage computer-aided screening system that analyzes fundus images with varying illumination and fields of view, and generates a severity grade for diabetic retinopathy using machine learning. The contents sharing system comprises plural devices connected with each other via a network. The light emitting unit has a plurality of light emitting components installed within the installation space of the reflection unit. The second clutch allows rotation between the first member and the second member when the first torque is greater than the predetermined holding torque. For example, retrofitting generally involves replacing the conventional polymer processing screw with a new screw designed to satisfy conditions needed for processing microcellular materials.