Changes in stereoscopic depth perception caused by decentration of spectacle lenses

The effect that decentered spectacle (ophthalmic) lenses exert on depth per ception has been studied, evaluating stereopsis through the disparity range (maximum horizontal disparity) for random-dot stereograms (RDS). The resul ts show that variations in fusional convergence due to increments of decent ration can diminish the stereopsis in observers, reducing the region within which stereoscopic correspondence can take place. Decreases in disparity r anges were found for vertical and horizontal prismatic effects, although th e prismatic effect necessary for this was less in the vertical case. A decr eased disparity range has also been confirmed with figural-stimuli stereogr ams and using prisms for generating the prismatic effects.