Chiastoptic vs Chiastopic

Abstract

To the Editor. —O tempora! O mores! declaimed Cicero as the orator arraigned Catiline for his boldness. Such were my thoughts when I read the correspondence by Brod and Packer 1 in the January 1988 issue of theArchivesthat stated that cross-fixational direct stereopsis can be learned easily by nonpresbyopic subjects. Indeed, I have used this simple technique for some years to fuse sequential stereoscopic roentgenographic images, fundus photographs, and fluorescein angiograms. Alas! I must remind the authors of a grammatical slip in their use of the term chiastopic . Its construction appears to derive from two Greek roots: (1) chiasma , from the 22nd letter of the Greek alphabet, x, which describes two crossing lines and, thus, a cross or decussation, and (2) topos , meaning a spot or place. A similar construction is seen with the prefixes en - (in, within) and ek - (out of), as in entopic or ectopic . Thus, an