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Continuing Blindness
Continuing blindness, on the other hand may be caused
by injury or disease which affects any of the
substances through which light passes on its way to
the retina or the layer of light-sensitive tissue that
lines the back and sides of the eye. Diseases
affecting the retina themselves can cause blindness,
as can diseases of the optic nerve or the visual
centers of the brain. Also, some infectious diseases
such as tuberculosis, meningitis, measles, diphtheria
and scarlet fever are known to cause blindness.
Atherosclerosis
A condition known as atherosclerosis, where fatty
plaques form in the linings of blood vessels, may
block blood supply and cause shriveling of retinal
tissue and the optic nerve. Another condition wherein
the cornea becomes soft and cloudy, owing to diseases
that result from nutritional deficiencies, may cause
blindness.
Diabetes
Non-infectious systemic diseases such as diabetes too
can cause blindness, as the retina may get damaged or
the condition can cause cataracts to form. Cataract is
a disease of the eye. It refers to the opacity of the
crystalline lens of the eye. Conditions such as
punctuate cataract or blue dot cataract, wherein the
opaque areas are minute scattered dots or cataracts
where only the periphery of the lens is affected do
not significantly reduce vision in the eye. Cataracts
can be congenital too.
Venereal diseases
Venereal diseases may cause blindness. In the case of
infants and children, untreated syphilis in a pregnant
woman can result in imperfect development of the
baby's eyes, as also German measles if contacted by
the pregnant mother during the first three months of
pregnancy.
Glaucoma
Glaucoma is another disease of the eye that causes
blindness. When there is an increase in pressure
within the eye, resulting from blockage of flow of
aqueous humor, a watery fluid, there results glaucoma.
The aqueous humor is produced by a ring of tissue
located directly behind the outer rim of the iris. Any
blockage of the aqueous humor flow causes increased
pressure in the posterior chamber, a narrow space
bounded in front by the iris. The pressure is
transmitted to the optic nerve head and the retina.
Abnormally high intraocular pressure that is
unrelieved causes vision impairment. |
