A ome magnifier is a dome-shaped magnifying device made of acrylic plastic typically that enlarges words on a page or computer screen into a larger image . Most dome magnifiers' perimeters are from 3 to 7 inches. They usually magnify to ×4 . Dome magnifiers are mainly used by the visually impaired. They are good for reading maps or basic text and their inherent 180° design naturally amplifies light for ambient illumination.