RADAR, ASTRONOMY, AND OPHTHALMOLOGY
In the 1960s radar signals were bounced off the planet Venus—in effect permitting calculation of the dimensions of the solar system within inches. This measurement depended on determining the delay in the return radio echo within microseconds. A major difficulty was overcome by sending a coded signal permitting the exact measurement of time delay by using identified items in the code rather than just the beginning and end of the radio signal as the beginning and end were usually muddied by background noise. Compare with estimating the distance from a lightning flash by counting the several second delay in hearing the associated thunder. (Sound requires about 5 seconds to travel one mile). A computer program was subsequently written that permitted identification of the coded signal without the confounding background noise.
Some “Renaissance” mind crossed the great gap between astronomy and ophthalmology to conceive the plan of doing visual field testing electronically. In visual fields testing, the patient fixes his gaze on a spot in the center of the screen. His visual field is measured by the area of the screen where he can perceive a spot of light or movement. In the electronic method a coded series of flashes with a fixed pattern is used. The same computer program that detected vestiges of the radar signal returning from Venus could detect vestiges of the flashing signal in the EEG (brain waves) of the optical cortex where visual information is processed, but only if the signal was flashing in a portion of the visual field where functioning retina and visual tracts could carry the signal to the brain. One advantage is that this method does not require cooperation from the patient and can even be done on an unconscious patient by holding the eyelid open and aiming the eye at the screen.
Visual fields testing is most often done to check on the success of treatment for glaucoma, a disease caused by increased pressure of the fluids in the eyeball. Long before blindness occurs, the visual fields are constricted. Neurologists use visual fields testing to help localize damage to the nerve tracts carrying visual signals to the brain.
The vast majority of visual field testing is done in the old way; but I was intrigued by how quickly the mind of man conceived of using the radar processing computer program for this seemingly unrelated purpose.
John A. Frantz, M.D.
September 26, 2002
How Sears Roebuck stifled the appreciation of Latin poetry
I knew a gentleman, who was so good a manager of his time, that he would not even lose that small potion of it which the calls of nature obliged him to pass in the necessary house, but gradually went through all the Latin poets in those moments. He bought, for example, a common edition of Horace, of which he tore off gradually a couple of pages, carried them with him to that necessary place, read them first and then sent them down as a sacrifice to Cloacina; that was so much time fairly gained, and I recommend you to follow his example…. It will make any book which you shall read in that manner very present in your mind.
Lord Chesterton in a letter to his son, 1924