Fig. (3) Schematic eye showing that light redirected superiorly (A) by the tear prism could pass through a superior laser peripheral iridotomy (LPI) otherwise hidden by the upper lid and would strike the superior peripheral retina after a short path, thus remaining relatively focused, and light passing through a temporal (B) laser peripheral iridotomy (LPI) would continue in a straight line toward the temporal posterior pole following relatively longer path, creating a defocused image (from 47, with permission, photo by courtesy of Elsevier).