A display system may include a wearable display for rendering a three-dimensional virtual image content which appears to be located in an environment of a user of the display. The relative positions of the display and one or more eyes of the user may not be in desired positions to receive, or register, image information outputted by the display. For example, the display-to-eye alignment may vary for different users and/or may change over time (e.g., as a user moves or as the display becomes displaced). The wearable device may determine a relative position and/or alignment between the display and the user's eyes by determining whether features of the eye are at certain vertical positions relative to the display. Based on the relative positions, the wearable device may determine if it is properly fitted to the user, and position render camera(s) accordingly to present virtual image content.