Abstract: Disclosed herein are viewing systems configured for viewing an image of a biological object illuminated with light and a viewing device (e.g., loupes, glasses, etc.) and methods for operation thereof. The viewing device comprises a plurality of viewing modes: a white light mode, a fluorescent light mode, and an overlay mode, and a shutter that opens and closes in accordance with the viewing mode. An overlay image is an image of the biological object when the biological object is illuminated with both white light and fluorescent light, causing the overlay image to be an overlay of the white light image and the fluorescent light image. The disclosed systems and methods allow a user (e.g., a surgeon, medical staff, etc.) to preserve the ergonomics offered by eyewear while providing fluorescent viewing capabilities, particularly with visible fluorescent dyes.