This consists in an increase of the media of the eye so as to cause an
excessive increase in size, and an unsightly bulging outward from the
orbit and between the lids. It may be said to be a more exaggerated
enlargement of the eye ball, than has been already noticed under
glaucoma.
It has been seen in nearly all classes of domestic animals. Everhardt
and Möller reports it in horses, Hausmann, Pradal, etc., in cattle,
LaNotte, in lambs, Cöster, Trasbot, etc., in dogs, and Trasbot, in birds
(chickens and parrots). It has been found congenitally in lambs and at a
few days old in foals, especially when weak and puny; in older animals
it appears to be most frequent in the anæmic or starved animal, in the
lymphatic, or, as in man, in the goitrous.
The manifest projection outward of the eye may occur as a nervous
phenomenon, without intraocular pressure, and without abscess, neoplasm,
or inflammation in the depth of the orbit. In a case of tuberculosis in
a three year old cow, I have found this condition, with normal tension
of the eyeball, but with acute tubercular meningitis of the pia,
surrounding the pons and crura cerebri, a grayish exudate with lighter
miliary centres, and a considerable clot of extravasated blood.
_Symptoms._ Mostly without any febrile reaction, there is a manifest
enlargement and bulging of the globe of the eye, so that it stands out
between the lids which can no longer cover it. The cornea, aqueous,
lens, and vitreous are not usually opaque, but show only a pale, blue,
opalescent tint. The pupil is often widely dilated so as to show clearly
the interior of the eye. Vertiginous symptoms have been observed in the
cow (Pradal), the supposed result of intraocular pressure.
_Treatment_ has had little effect when it stops short of puncture of the
cornea or iridectomy.