To her the blindness was real, and her friends feel that a remarkable cure has been performed. Such a blindness can occur in any nervous hysterical patient, while simulated blindness usually occurs in those who wish to avoid service in the army or navy, or in the case of lazy young people who do not wish to study at school or college, and in those who have received a slight injury and wish to make it appear more serious for the sake of obtaining large damages, either from private individuals or corporations.
For its detection there are several methods which are usually sufficient to give us positive proof that the blindness is not real. Von Graefe placed a number eight or ten prism in front of the eye, with the base upwards, downwards or sidewise, and if strabismus is present before the removal of the prism there is binocular vision.
Juler places spectacles with an opaque glass in front of the good eye, when, if the patient can read, he must see with both eyes; or he places concave 20 before the good eye, when if the patient can read fine print he must see it with the other eye.
Juval places a ruler before the eye so as to cover part of the page to be read, when, if one eye is blind, not all the page can be read.
Mittendorf puts atropine in the good eye, when if the patient can read fine print he is not blind with the other eye.
Wells places a prism in front of the supposed blind eye, and notices whether the apis of vision of that eye changes when the prism is removed.
Bull bandages the good eye and places a prism in front of the other eye, and holds a lighted candle before the eye, and if the eye turns as the prism is turned, the eye is not blind.
The test with Snellens or other colored letters is also a good one. A word with alternate red and bluish green letters is painted on glass and placed in the window, and the patient is asked to read the letters. If a bluish green glass is held in front of the good eye, he will see only the green letters unless he can see with the other eye, for all but the red rays in the red letters are cut off in the transparency in the window, and the green glass cuts the red off, leaving those letters a perfect blank to the well eye.
Kugel places various colored glasses before each eye and then places an opaque glass in front of the sound eye, and a transparent glass of the same color before the other one, and if the patient sees the object, he is simulating blindness.
Herring has the patient look through a tube large enough to cover both eyes, and then suspends a small ball in front of the tube and drops small objects near this ball, and if the patient can tell whether the balls are dropped in front of or behind the suspended ball, he must see with both eyes.