An optical module for a head-mounted device is configured to present content to a user. The optical module includes an optical module housing assembly, a display assembly, and an eye camera. The optical module housing assembly has a first end and a second end. The lens is connected to the optical module housing assembly and positioned at the first end of the optical module housing assembly. The display assembly is connected to the optical module housing assembly and is positioned at the second end of the optical module housing assembly. The display assembly is configured to cause the content to be displayed to the user through the lens. The eye camera is connected to the optical module housing assembly and is positioned at the second end of the optical module housing assembly. The eye camera is configured to obtain images through the lens.