tra work is thrown on the ciliary muscle as well as the muscles that
move the eyeballs. The result is frequently to induce a condition, known
as _muscle weakness_, which renders it difficult to use the eyes. Even
after the defect in focusing has been remedied, the muscles recover slowly
and must be used with care. For this reason glasses should be fitted by a
competent oculist(126) as soon as a defect is known to exist. When one is
unduly nervous, or suffers from headache, the eyes should be examined for
defects in focusing (page 326).

*Eye Strain and Disease.*--The extra work thrown upon the nervous system
through seeing with defective eyes, especially in reading and other close
work, is now recognized as an important cause of disease. Through the tax
made upon the nervous system by the eyes, there may be left an
insufficient amount of nervous energy for the proper running of the vital
processes. As a result there is a decline of the health. Ample proof that
eye strain interferes with the vital processes and causes ill health, is
found in the improvements that result when, by means of glasses, this is
relieved.

*The Eyes of School Children.*--School children often suffer from defects
of vision which render close work burdensome, and cause headache, general
nervousness, and disease. Furthermore, the visual defects may be unknown
both to themselves and to their parents. Pupils showing indications of
eye-strain should be examined by an oculist, and fitted with glasses
should defects be discovered.(127) The precaution, adopted by many
schools, of having the eyes of all children examined by a competent
physician employed for the purpose, is most excellent and worthy of
imitation.

*Reading Glasses.*--Many people whose eyes are weak, because slightly
defective, find great relief in the use of special glasses for reading and
other close work. By using such glasses they may postpone the time when
they are compelled to wear glasses constantly. It is in the close work
that the extra strain comes upon the eyes, and if this is relieved, one
can much better withstand the work of distant vision. The reading glasses
should be fitted by a competent oculist, and used only for the purpose for
which they are intended.

*General Precautions in the Use of the Eyes.*--If proper care is exercised
in the use of the eyes, many of their common ailments and defects may be
avoided. Any one, whether his eyes are weak or strong, will do well t