New Technique for the Measurement of Small Eye Movements *

A University of California author or department has made this article openly available. Thanks to the Academic Senate's Open Access Policy, a great many UC-authored scholarly publications will now be freely available on this site. Let us know how this access is important for you. We want to hear your story! Title: New technique for the measurement of small eye movements. acuity as the angular velocity of the test object is when the test object is stationary, visual acuity is increased is similar not only when the test object is substantially benefitted by increases up to and probably moved horizontally or vertically but also if the observer exceeding 125.00 ft-c when the observer is rotated in is rotated in a horizontal plane. the horizontal plane. When the observer is stationary (2) The semiempirical equation Y= a+bx 3 describes and the object is moved in a circle in a plane perpendicu-satisfactorily the data obtained for horizontal and lar to the line of sight visual acuity has been shown to vertical movement of the test object as well as that be benefitted by an increase of illumination up to 500 obtained when the observer was rotated horizontally. ft-c. It therefore seems that the relationship is a general (3) An individual whose visual acuity is susceptible one which will also hold when the test object is moved to increases in angular velocity in the horizontal plane relative to the observer's eye in any plane. will very likely be velocity susceptible in the vertical (5) The higher the relative angular velocity of the plane of pursuit. test object the greater must be the intensity of illumina-(4) Although 5 to 10 ft-c is adequate illumination-tion in order to maintain a given visual acuity threshold. A technique has been developed for recording eye movements as large as three or four degrees, with a precision of about ten seconds of arc. The technique is not subject to artifacts when the head moves, or if the eye should shift in its socket, and no attachment to the eye is required. A very small spot of light is focused on the subject's retina and is made to scan repeatedly across the optic disk. Light reflected back out of the eye is projected on to a photomultiplier tube which drives the vertical amplifier of a cathode-ray oscilloscope. The horizontal sweep of the oscilloscope is triggered in synchrony with the scanning …