—According to the Dictionary of Visual Science,1chiastopic fusion is "fusion obtained by voluntarily converging to fixate directly two fusible targets, laterally separated in space, such that the right eye directly fixates the left target and the left eye the right target." However, we respectfully defer to the expertise of the classics scholar from Houston, because, in matters etymological, all we can say is "It's Greek to us."
Brod RD, Packer AJ. Chiastoptic vs Chiastopic-Reply. Arch Ophthalmol. 1988;106(6):723. doi:10.1001/archopht.1988.01060130793018