Mr. R. D. L., aged 30, an engineer, came to me for help, complaining of vision with his present spectacles. For the past nine years he had been wearing glasses. One of 3 children, he was the only sibling with defective eyesight. His mother had a high amount of myopia in the right eye, and her left eye was emmetropic. His brother and sister both had normal vision. His condition was identical with that of his mother. His error of refraction was as follows: Right eye,—13.00 D sph., visual acuity 20/50—; left eye: —0.25 D. cyl., axis 180, vision 20/20. The high amount of myopia in the right eye corrected gave him a sizeimage difference. In August 1945 he was measured for his aniseikonia, and iseikonic lenses were prescribed. These spectacles gave him fusion and comfort, but only when the eyes were in primary fixation. As he moved his