That which more concerns the reader is, to learn the manner, if possible, of preventing cataract from disfiguring his horse's eyes. Then will the gentleman be kind enough to hold a sheet of white paper close to his nose, so that the eyes may see nothing else, for a single half hour. Let us suppose the trial has been made. With many people the head has become dizzy and the sight indistinct. In some persons singing noises are heard and a sensation of sickness has been created. Let the author strive to explain this fact. Travelers, passing over the Alps, wear green veils, to prevent the strain or excitement which looking upon a mass of white snow occasions the visual organs. Any excitement is prejudicial to the eye. Workers at trades dealing in minute objects, often go blind, and the use of the microscope has frequently to be discontinued. But to look continuously upon a white mass is the most harmful of all other causes.
This fact must be considered as established. And what does the horse proprietor have done to his stable? He orders the interior to be whitewashed. It looks so clean, he delights to see it; but do the horses—does nature equally enjoy to look upon those walls of "spotless purity?" Before those walls, with its head tied to the manger, stands the animal through the hours of the day. Close to its nose shines the painful whiteness which the master so enjoys. Is it, then, surprising (seeing how nature for its own wise purposes has connected all life) that the equine eye, doomed to perpetual excitement, sometimes shows disease?
A horse with imperfect vision is a dangerous animal. A small speck upon the lens confuses the sight as much as a comparatively large mark upon the cornea. To render this clear, let the reader hold a pen close to the eye; it prevents more vision than yonder huge post obstructs. So impediments are important, as they near the optic nerve. The lens is nearer than the cornea, and therefore any opacity upon the first structure is more to be dreaded.
However, let it be imagined a horse, with an opacity upon the pupil, and the sight confused by staring at a white flat mass spread out before it, is led forth for its master's use. By the aid of the groom and its own recollections, it manages to tread the gangway, and even to reach the well-known house door in safety. The owner, an aged gentleman, of the highest respectability, comes forth in riding costume. He mounts, and throwing the reins upon the neck of the animal, sets his nag into walking motion, while he, erect and stately, looks about him and proceeds to pull on his gloves. The horse, however, has not gone many steps before the cataract and the confused vision, acting conjointly, produce alarm. The steed shies and the gentleman loses his seat, being very nearly off. The passengers laugh, the proprietor suffers in his temper, but the whip is used, and the equestrian is soon out of sight.
The man and horse proceed some distance; the gentleman becomes much more calm, and the horse recovers sufficient composure to try and look around it. The pace now is rather brisk, when the horse thinks, or its disabled vision causes it to imagine, it sees some frightful object in the distance. The timid animal suddenly wheels round. The rider is not prepared for the eccentric motion: he is shot out of the saddle. He falls upon his head; he is picked up and carried home; but afterward he avoids the saddle.
Never buy the horse with imperfect vision; never have the interior of your stable whitewashed. Then what color is to be employed? Probably blue would absorb too many of the rays of light; at all events, it seems preferable to copy nature. Green is the livery of the fields. In these the eyes take no injury, although the horse's head be bent toward the grass for the greater number of the hours. Consequently, the writer recommends that green wash, which is cheap enough, should be employed, instead of the obnoxious white, for the interior of stables.
COMPLETE CATARACT.
For complete cataract nothing can be done. In man, operation or couching may be performed with success; but the horse can retract the eye and protrude the cartilago nictitans. Thereby difficulties are created; but these may be overcome. However, when an opening through the cornea is perfected, the spasmodic contraction of the muscles of the eye, acting upon the fibrous covering of the globe, is apt to drive forth the liquid contents of the organ in a jet: this is irreparable, of course. When so fearful a catastrophe does not ensue, still the capsule of the lens is always difficult to divide, and the lens itself cannot easily be broken down. The lens, therefore, must be abstracted; but that necessitates a large incision, which the previously named probability forbids. Displacement is the only resort left; but the lens, when forced from its situation into the posterior or dark cavity, is, by the contraction of the muscles, forced up again. The uncertainty of the result, even when the operation is successfully performed, is peculiarly disheartening. Half lose their eyes in consequence of the attempt; half the remainder are in no way benefited; to the rest, as these cannot wear spectacles to supply the place of the absent lens, of course the pain endured becomes useless torture.