Convergence insufficiency, basic exophoria and pseudo convergence insufficiency are three common reason for visual dysfunction. It's difficult for optometrist to differential diagnosis because of the similar signs and symptoms. Comprehensive analysis of distance & near eye position, accommodation, AC/A ratio and negative/positive relative accommodation(NRA/PRA)may help optometrist to make an accurate diagnosis and treatment strategy, which may relax asthenopia and maintain normal binocular vision.