Here's an interesting tidbit on the care of the eye from Dr. Chase's Home Advisor & Everyday Reference Book ©1894
As our greatest pleasures and knowledge are derived fiom the sight, so has Providence been more curious in the foundation of its seat, the eye, than in the organs of the other senses.—Sir A'. Steele.
The Eyes, and How to Care for Them.—The eye is not only the light-house to the soul, but it is undoubtedly the most valuable member of the human body, and I except none. It therefore behooves us to exercise every possible precaution for its preservation, and no words are too strong to serve as warning to those who wrongfully use or abuse the eye.
Care of the Eyes.—Never read in bed or when lying upon the sofa. Sit with your back to the light as much as possible. Attend to your digestion. Do not work longer than two hours without closing your eyes and resting them for five minutes. If your eyes are weak, bathe them in cold water to which a little salt and a little brandy have been added.
Don't work by twilight or by a flickering light. The rapidly diminishing light between sunset and dusk is most fatal to the eyes. Fine needlework, especially colored embroidery, should be pursued only in good light.
Don't read in direct sunlight, as the glare is a direct irritant to the retina. In reading by artificial light, the back should always be turned to the source of illumination, allowing the light to pass over the shoulders. When working by artificial illumination, the light should either be high enough to permit shading of the eyes by the brows, else an opaque screen, or, better still, a translucent shade should cut off the glare of the light from the eyes, and yet permit illumination of the work. The light of an oil lamp is, as a rule, better than that furnished by the average corporation gasburner.
The eye speaks with an eloquence and truthfulness surpassing speech. It is the window out of which winged thoughts often fly unwittingly.—Tuckerman.
In one case—not among the employes just spoken of—the contraction of the pupil was so great that the sufferer was unable to go about without assistance. He had smoked from twenty to thirty cigars a day. He renounced tobacco, and his sight was fully restored in three and one-half months.