A device for self-determining a person's pupillary separation in an OTC setting. In a first embodiment, the device includes a plurality of interconnected masks, each mask having two holes therein, the distance between the center of the holes being indicated on the mask. The separation of the holes is different for each mask. The user places the respective masks before the eyes and looks through the holes. The optimal interpupillary distance is determined by the clearest vision experienced by the user when looking through the holes. In a second embodiment, a single mask is presented wherein the distance between two holes is varied continuously until a single hole is perceived by the user, and the interpupillary distance read from a ruled scale on the device.
