Scientific American Supplement No. 822, October 3, 1891Various
Science
Scientific American Supplement No. 822, October 3, 1891
Various
Science -- Periodicals
Six horses were also examined, of which one had normal sight, three
were hypermetropic and astigmatic, and two had a slight degree of
astigmatism. They also examined other animals, and the same proportion
of hypermetropia existed. These gentlemen found that as an optical
instrument the eye of the horse, cow, cat and rabbit is superior to
that of the rat, mouse and guinea pig.
I have for the last five years devoted considerable attention to the
vision of the Indian children who are pupils at two institutions in
this city. I have at various times made careful records of each
individual pupil and have from time to time compared them. Up to the
present there is a growing tendency toward myopia or short
sightedness, i.e., more pupils from year to year require near sighted
glasses. The natural condition of their eyes is far sighted and the
demands upon them are producing many nervous or reflex symptoms, pain
over the frontal region and headaches. A good illustration of the
latter trouble is showing itself in a young Indian boy, who is at
present undergoing an examination of his vision as a probable cause
for his headaches. This boy is studying music; one year ago he
practiced two hours daily on the piano and studied from three to five
hours besides. This year his work has been increased; he is now
troubled with severe headaches, and after continued near work for some
time letters become blurred and run together. This boy is far sighted
and astigmatic; glasses will correct his defect, and it will be
interesting to note whether his eyes will eventually grow into near
sighted ones. I have several cases where the defective vision has been
due entirely to other causes, such as inflammation of the cornea,
weakening this part of the eye, and the effect in trying to see
producing an elongation of the anterior portion of the eyeball, and
this in turn producing myopia. The eye of the Indian does not differ
materially from that of any deeply pigmented race. The eyeball is
smaller than in the Caucasian, but when we examine the interior we
find the same distribution of the blood vessels and same shape of the
optic nerves. The pigment deposit in the choroid is excessive and
gives, as a background to the retina, a beautiful silvery sheen when
examined with the ophthalmoscope. One thing which I noticed
particularly was the absence of this excessive deposit of pigment and
absence of this watered silk appearance in the half breeds, they
taking after the white race.
Many of the intraocular diseases common among the white children were
also absent, especially those diseases which are the result of near
work.
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