BLINDNESS, CAUSES OF. The most reliable statistics which we possess deal with blindness in the first quarter of life. Here we find congenital anomalies causing 25% of blindness. These are unpreventable until the eugenic millennium is reached, but to an extent, useful vision may be obtained and preserved.
Ophthalmia neonatorum (gonorrheal ophthalmia of the new born) causes approximately another 25%. This disease is almost entirely preventable in modern practice. The disease is curable without damage in almost every instance provided the baby is treated early enough. Blindness due to this is decreasing.
Syphilis, mostly congenital, probably causes Io% of blindness, mostly through interstitial keratitis and uveitis. It is entirely preventable ; it is possible by modern treatment to reduce materi ally the amount of blindness caused.
Atrophy of the optic nerve, not over 5%, is largely, though not entirely, unpreventable. Myopia in its "pernicious" form, 3% of blindness, is controllable if taken early. Phlyctenular keratitis, 2%, largely dependent on tuberculosis and poor hygiene, is pre ventable and remediable.
To injuries may be ascribed from 5% to 8%. In a considerable group of diseases of the eye, cornea, uveal tract, retina and optic nerve leading to blindness, the cause factor is doubtful.
It will be seen that in this early age group a very large pro portion of blindness is preventable. In later years of life, statistics of blindness are, in the main, very unreliable, and only facts will be given which seem reasonably certain.
Injuries, especially in men, cause 7% to 1o% of blindness, largely preventable through protective devices. In connection with this group, sympathetic disease as a cause of blindness was almost negligible in the World War. If the war blind in Germany, France and England are counted among the injuries, at least 5% must be added.
Syphilis (acquired), largely through disease of the uveal coat and optic nerve, is responsible for 1 o% to i 5 % of blindness, which is largely preventable and remediable if treated early.
Myopia, the cause of blindness in 14%, is controllable if taken in childhood. Glaucoma is of slight importance in infancy, youth, and up to middle age, but after the age of 45 becomes the most important cause of blindness, amounting to from 25% to 35% in the latter half of life. The acute congestive type is amenable to operation in the early stages and thus remediable. The simple, non-congestive type and secondary glaucoma, if taken early, are remediable to a considerable degree. Untreated, glaucoma always leads to blindness.
Atrophy of the optic nerve, a common cause of blindness, is estimated as high as 18%. It is frequently due to syphilis and in that case preventable. Also preventable and remediable to a cer tain extent is blindness due to accessible tumors, etc.
Diseases of the uveal tract (iritis, cyclitis, choroiditis) are responsible for a considerable group of the • blind. In part, these are caused by syphilis, tuberculosis, focal infections in various parts of the body, general disease, and unknown causes, and they are to a certain extent remediable. General systemic conditions, such as nephritis, diabetes and arterio-sclerosis may cause blind ness in their terminal stages.
Trachoma probably causes 5o% of blindness in certain parts of China; in Missouri, U.S.A., the figure is Generally it is an unimportant cause and the results are preventable. Small pox is said to cause 2o% of blindness in Mexico. (G. S. DE.)