This section is from the book "The Home Hand-Book of Domestic Hygiene and Rational Medicine. Volume 2.", by J. H. Kellogg, M.D.. Also available from Amazon: The Home Hand-Book of Domestic Hygiene and Rational Medicine, Volume 2.
This is a condition of the eye in which the curve of the cornea is not symmetrical, or uniform. The consequences of this condition are much more serious than those resulting from long or short-sightedness. Nearly all objects are seen distorted. The most perfect eye is not absolutely symmetrical, and when the want of symmetry is more or less increased, the eye becomes astigmatic. A person suffering with this affection of the eye can easily see horizontal lines more distinctly than vertical ones, though sometimes the reverse is the case. This condition may be detected by means of the test diagram. Fig. 454 If this is held a distance from the eye and gradually brought near to it, it will be discovered that either the horizontal or the vertical lines indistinct. In some cases, this is true of the oblique lines, instead of the vertical or horizontal.
Fig. 454. Test for Astigmatism.
Astigmatism, like long-sight and short-sight, but in a much greater degree, has a considerable effect upon the character. Persons who are bom with this defect never know the proper forms of objects until the defect is corrected by the proper glasses. We have now under treatment a lady who never knew the form of the human face until a pair of glasses were fitted to her eyes. The change in the appearance of objects was so great that she at first was unable to recognize her husband without taking off her glasses. She expressed the most exquisite delight at the improved appearance of various objects which she beheld for the first time in their proper form. Astigmatism is corrected by means of glasses ground from a cylinder in such a way as to overcome the optical defects of the eye.