Causes: harness, whip, nail, hay, straw, stubble, thistles, spikes,
twigs, pine needles, cones, burdocks, stones, gravel, glass, splinters
of wood or metal, scratches, stings. Symptoms: closed lids, epiphora,
sight of lesion, soon cloudy swelling, opacity. Treatment: antiseptic
bandage and lotion, boric acid, sublimate, potassium permanganate,
avoid lead or zinc, atropia, cocaine, with perforation, bandage,
eserine, excision. For foreign body, antiseptic cotton, spud or
curette.
_Causes._ Corneal wounds are common in working animals by reason of
contact with harness, canes, whips, etc., and in the stable from contact
with nails or with the hard ends of hay or straw. At pasture the cornea
is injured by the ends of long stubble, the sharp points of thistles,
the spikes of various thorny plants, and twigs of bushes and trees. The
last named factors are especially operative in hunters and horses worked
in forests. Punctures with pine needles and cones, and with burdocks,
are other common causes. Stones, gravel, pieces of glass, and splinters
of wood or metal, produce traumas of the cornea, and, in cats and dogs,
scratches and even perforations with the claws are common. In this
connection the stings of insects are not to be forgotten.
_Symptoms._ There is always a prompt and complete closure of the eyelids
and a profuse secretion of tears. Then on parting the eyelids with
finger and thumb, the lesion of the cornea, its nature and extent should
be recognizable. In case of a small, punctured wound, however, as with a
smooth thorn or other conical body, the normal elasticity of the corneal
tissue may lead to such a perfect coaptation of the divided edges that
the lesion may escape even a close scrutiny. If the case is seen early,
before time has been allowed for cloudy swelling and opacity the wound
is all the more likely to escape observation. In incised, scratched and
torn wounds, on the other hand, the seat and nature of the lesion are
made out with the greatest ease.
_Treatment_ of a slight wound which is at once recent and free from
infection, is by a simple antiseptic bandage and lotion. Boric acid (1 ∶
100), sublimate solution (1 ∶ 5000) or potassium permanganate solution
(1 ∶ 100) may be used. Lead and even zinc salts, are liable to
precipitate in the abraded tissue and cause a lasting opacity. If the
pain is severe it may be moderated by the addition of atropia sulphate,
or a solution of 1 to 100 water may be instilled into the eye several
times daily. Cocaine makes an excellent substitute. In deeper wounds,
perforating the cornea and allowing the escape of aqueous humor, there
may be prolapse of the iris through the wound. It may be pressed back
with a flat sterilized spatula, and retained by bandage and a course of
eserine. Should it still escape, it must be seized with forceps, drawn
out and snipped off with a sharp pair of sterilized scissors. The
greatest care must be taken to avoid infection which may cause
panophthalmitis and destruction of the entire eyeball.