Recent experimental work has shown that the space eikonometer is a suitable instrument for the measurement of aniseikonic errors.1 This instrument2 differs from the standard eikonometer in that the measurement depends on binocular (stereoscopic) perception rather than on a direct comparison of image sizes. In the space eikonometer all empiric clues which might affect the apparent relative positions of selected test elements are eliminated, and their apparent orientation can be perceived only by binocular (stereoscopic) space perception. If an aniseikonic error exists between the two eyes, these test objects will appear incorrectly oriented to the subject, according to the nature of the error present. By means of suitable size lenses the relative sizes of the images in the two eyes can be changed until the test objects appear correctly oriented.3 The magnifications introduced to achieve this measure the aniseikonic error.
To complete the study of the visual
OGLE KN, ELLERBROCK VJ. STEREOSCOPIC SENSITIVITY IN THE SPACE EIKONOMETER. Arch Ophthalmol. 1945;34(4):303–310. doi:10.1001/archopht.1945.00890190305006