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June 1988

Chiastoptic vs Chiastopic

Arch Ophthalmol. 1988;106(6):723. doi:10.1001/archopht.1988.01060130793017

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 Packer1 in the January 1988 issue of the Archives that 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

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