AMAURO'SIS (Gr. anzauros, obscure) is a blindness or obscurity of vision caused byl disease of the optic nerve, and this cause may be situated either at the origin of the nerve in the brain, in some part of its course, or at its termination in the retina ; and of course the degree of blindness will be in proportion to the extent these parts are in volved by the disease. See OPTIC NERVE. A. may also depend upon causes remote from the organ of vision ; the suppression of accustomed discharges from the body may lead to congestion of the vessels of the brain, and cause A.; and it may spring from many very slight causes, if a predisposition to the disease exists. This is occasionally hereditary. Beer mentions several cases in one family; for three successive generations, all -the females who had not Borne children became blind in middle age; the males showed a tendency to the disease, but did not become blind. A common cause is ex.
posure to bright light or great heat and light, either natural or artificial, occupation upon minute objects, and employment of the eyes during the hours which ought to be devoted to sleep. In many instances, a single imprudent exposure of the eyes to the operation of some such cause, has been sufficient to extinguish the sensibility of the retina; but, in general, it is from long-continued over-excitement of the organs of vision that they begin to fail, and at last become totally unable to continue their office. The heat of the sun, rage, continued stooping, and fevers or other causes, causing con gestion, inflammation, or serous effusion in the head, cause A. Soipe poisonous substances cause A. suddenly, as belladonna, stramonium, and other narcotics given in large doses ; and others, applied to the body every day in small quantities, have the same effect, but more slowly. Tobacco may be justly signalized as a poison of this
sort, as also mercury and lead.
Exhaustion of the body and depressing mental affections also are causes of A. But we can seldom attribute its occurrence to the Influence of any single remote cause, but to a number of circumstances which have been acting for a length of time upon one individual, either consecutively or together.
We recognize the presence of A. by the history of the case and the appearance of the eyes. The latter have generally a vacant, unmeaning stare, dilated pupils, and do not converge towards an object, hut appear to be looking steadfastly at something in the distance. The sclerotic or white of the eye is generally altered in color, and crossed by enlarged blood-vessels. The history of the case varies with the patient. Among the first symptoms are difficulty in calculating distances, as in threading a needle or pouring fluid into a glass; and sometimes there is occasional loss of sight in one eye (amaurosis rage), confusion of vision—sometimes a part of the field of vision will be clear, and part obscured. There are also present spectra or muses volitantes, which sometimes are permanent, arising from the existence of insensible patches on the retina. Floating specks are merely coincident with the disease.
A. is treated by depletion in the robust, alteratives and tonics in the feeble, and by those remedies which act upon the nervous system, and counter-irritation by blisters or issues behind the ears, or in the neighborhood. Except in very recent cases, the pros pect of recovery is slight.