Page:Popular Science Monthly Volume 47.djvu/474

460 observe an artist at his work. Having arranged on his palette a variety of pigments, he stands before the easel and applies them to the canvas, but at intervals steps back some few feet in order to get the effect of distance, as he says. It should be noticed that almost without exception the artist when doing this partly closes his eyes, pressing the lids together, making "clingement" as the French call it, because, as he explains, "better effects" are thus obtained. At the same time he tips his head from one side to the other, the reason for which we will consider later. Now, if the eyes of persons with ordinary occupations are changed, as we have seen, by the pressure of the upper and lower lids upon the globe, it is but natural to infer that the same result would follow even in a greater degree with persons whose occupation from morning until night, year in and year out, is such as to cause them to practice to an unusual degree this habit of clingement, or lid pressure upon the cornea. Indeed, this fact has long since attracted the attention of investigators and has been demonstrated and elaborated by Bull, of Paris, and others. Dr. Bull experimented on his own eyes, having them measured exactly by an instrument of wonderful exactness known as the ophthalmometer while he was making this lid pressure. These measurements showed that even this slight momentary contraction of the lids produced a perceptible increase of the unequal curvature of the cornea, and also that a very high degree of astigmatism could with little effort be produced by pressure of the lids.

Very strong a priori reasons, therefore, lead us to expect that the eyes of artists are as a rule more imperfect than those of persons with other occupations. I have taken pains, however, to establish this fact by tests and measurements. The first results of that investigation are given in the American Journal of Ophthalmology for October, 1894, and tests have been made at intervals since then of the vision of artists, record being kept of the variety of work done, style preferred, whether the individual practiced lid pressure habitually or not, and other details of a technical nature. Excluding those on the one hand who were too young in the profession to be really classed as "artists," and on the other hand those whose eyes were practically in a diseased condition, the list thus far includes eighty-four artists, or one hundred and sixty-eight eyes.

Among these, not a single eye was found to be without some astigmatism. This is not surprising, but the degree of astigmatism is significant.

In the series of two hundred eyes already referred to as examined by Dr. Roosa, which had every indication of being absolutely perfect, an exact examination showed that there was, on the