sentences:  These instruments include Worth's amblyoscope and the synoptophore.Commonly haploscopes employ front-surfaced mirrors placed at different angles close to the eyes to reflect the images into the eyes.Reputedly the largest haploscope, with images of over a meter (in fact, 4 feet) square and a viewing distance for each eye of nearly five meters (16 feet), was constructed by Vaegan in about 1975 to research stereoacuity.