The brief observations here presented are to be regarded as addenda to the paper on the subject read by the author before the Pan-American Medical Congress in 1893.
Probably in every case of cataract extraction the necessary corneal section is followed by a permanent change in the corneal curvature and refraction. In a few cases the change in curvature is such as to reduce or correct, or slightly over-correct, a previously existing asymmetry of the cornea, and the astigmatism caused by it. In the larger proportion of cases the ultimate effect is a considerable astigmatism, greater in amount and essentially different in direction from any astigmatism that may have been present before the operation.
The fact that the astigmatism is new, and also that it is due to change in the corneal curves, give it increased importance. Those who always have had astigmatism never perceive the distortion of retinal images