BLIND, ASYLUMS FOR THE.—Aside from the institutions for the care of the blind which are known to have existed in China thousands of years ago, the first asylum of this kind was founded in Paris, in the year 1784. Shortly afterward, similar institutions were started in Liverpool, Edinburgh, Bristol, and London. Asylums were founded in Berlin and in St. Petersburg in 1806 ; in Vienna, 1808 ; and in Dresden in 1809. At the present time almost every civilised country is amply supplied with asylums of this character. As a rule they have been founded by private individuals, the state having lent its assistance at a later date. In some countries attend ance is obligatory ; the children are entered at the age of six, and remain under instruction until the eighteenth or twentieth year. After that they either follow their own inclinations, or are provided for in special avenues of employment connected with the institution.
In the United States the earliest institution of this kind, the New England Asylum for the Blind, was founded in 1829; in Boston. It was opened in 1832, a few months after the opening of the New York Institution for the Blind. In the following year (1833) a school for the blind was opened in Philadelphia ; and in 1899 there was 4o such schools in the United States, a special school for the coloured blind having been opened in 1869. All the States of the Union now make provision for the blind.
BLINDNESS.—Term referring to the inability of an eve to perceive light ; practically, however, the designation of " blind " is applied to indi viduals whose sight is impaired to such an extent that they cannot find their way about. In most countries where vaccination is universally employed, the number of the blind has markedly decreased. Where this operation is not compulsory or is not used to any great extent, smallpox is the most frequent cause of blindness. .1t the present time the most common cause of blindness among civilised peoples is the purulent, or gonorrhoeal, conjunctivitis of the new-born.
Blindness may come on at any time of life, when the transparent parts of the eye become impervious to light as the result of extensive corneal cloudiness, closure of the pupil from inflammation of the iris. cataract, diseases of the retina and choroid, affections of the optic nerve, or severe injuries to the eye. Diseases of the brain and spinal cord may also bring on blindness. As a general rule, cases of blindness which are congenital, or which are due to disease of the retina, the optic nerve, or the brain, must be looked upon as hopeless. Partial blindness is a term applied to that condition in \\•nch a portion, even one-half, of the visual field of one or both eyes is affected, so that the patient is blind in spots (amblyotia) or sees only those objects which happen to come on either the right or the left side of the median line (honianopsitt). Such forms of blindness usually result from injury to the nervous elements of the eye.
The term " psychic blindness " or " mind blindness " is applied to a condi tion in which, as the result of deAruction of certain portions of the brain, the patient can still see, hut is unable to interpret what he sees.
BLISTER—An effusion of serum underneath the superficial skin. It may be brought about by an irritating agent, extreme heat (as in a burn), extreme cold (as in freezing), or by a variety of other physical and chemical agents. Thus X-rays, the electric spark, radium, etc., can cause blisters on the skin ; or they may be produced by such substances as mustard, can tharides, and similar pharmaceutical agents. In medicine, blisters are most frequently produced by mustard, cantharides, turpentine, or by the actual cautery. The chief action of a blister is as a counter-irritant. Whereas it is frequently believed by the laity that such blisters draw the morbid matter to the surface, and that thus the cause of an illness is removed, the true action is far different. It consists really in setting up a nervous reflex action in the sympathetic nervous system. It has been established that practically every internal organ of the body has a representation in the superficial layer of the skin, and that influences acting on the organs may show themselves by changes of greater or less degree of definiteness in these superficial, related areas. Conversely. irritations of these areas in their turn can bring about modifications in the activity of the organs themselves, particularly the matter of their blood supply.
In the endeavour thus to modify the internal organs, or parts lying in close proximity to the organs, this counter-irritation may be used. Thus, in the treatment of pleurisy and pneumonia, counter-irritation is helpful to give muscle-tone to the blood-vessels of the lungs and pleura, and it may assist in preventing over-distention. with resulting paralysis, in these blood vessels. Counter-irritation is also widely employed to overcome neuralgia. Mere the counter-irritation is thought to bring about a similar modification in the condition of the blood-vessels of the nerve-trunks and the good effects that follow application of the actual cautery, or of fly-blister, along the course of the sciatic nerve in sciatica are to be interpreted in some such manner.
Blisters are very frequently used in other regions of the body. Thus, used on the knee-joint they are helpful in diminishing suffusion or the col lection of water on the knee ; at the back of the neck they are often useful in relieving chronic headaches ; and in chronic joint-diseases in general they are often very helpful. In the use of blisters, care should be taken that the serum does not become infected.
The use of blistering agents has diminished considerably within recent years, as newer and more effective modes of treatment have come into service for such affections in which blisters \ vere formerly used. The aru ment is not that blisters are no longer effective—they are as useful as ever —but that other methods of treatment are even more serviceable.
BLOOD.—See INTRODUCTORY CHAPTERS (pp. 107-109).
BLOOD-DISEASES.—See AN.EMIA ; BLOOD-POISONING ; H.n310PHILIA VENEREAL DISEASE.