FREE ESSAY ON VISUAL IMPAIRMENT

VISUAL IMPAIRMENT

Vision Impairments
People catergorized as visually impaired range from individuals with mild visual losses
to those with low vision to those who are totally blind (Winzer,370). Vision impairments
does not necessarily mean a total loss of sight. Some visually impaired person can detect
light, others can see shapes and forms, and others can see nothing at all. Generally,
many different problems that interfere the retina to form image or the transmission of
retinal images to the brain can cause blindness or vision impairment. It can be heredity
or caused by disease or damage after birth. In some cases a specific reason cannot be
determined.
There are four major types of vision impairments. The first type are refractive errors.
It is cause by the change of shape or size of the eyeball, conera or the lens. Myopia
(short-sighted) and hyperopia (long-sighted) are two common examples. People with myopia
or hyperopia cannot focus image accurately on the retina. Another example is astigmatism,
it is caused by the abnormal curve shape of the cornera or the lens. And it can cause
distorted or blurred vision.
The second type are ocular motor problems. It is caused by irregular movement of the
ocular muscles that control the movement of the eyeballs. It leads to the inability for
the eyes to control focusing objects. Strasbismus is an example. This condition effects
about 2 percent (2 out of 100) of all young children. Strabismus is a lack of coordinated
muscle movement or focusing ability between the eyes, causing the eyes to point in
different directions. One or both eyes may turn inward (crossed eyes) or outward
(walleye). The eyes, the brain area that controls vision, and the muscles attached to the
eyeball are involved. It result in the child that looks in certain directions, double
vision (sometimes), vision in one eye only, with loss of depth perception. Strabismus can
affect both sexes, all ages, but it usually begins during early childhood, frequently
before age 5. If not corrected through therapy or surgery, crossed eyes can result in
permanent loss of vision. 
The third type are eye diseases, it is caused by damage or disease before or after birth
to one or more structure of the eye (Winzer, 374). One off the most common causes of
blindness is cataracts. Cataracts are a clouding of the lens of the eye that keeps light
from reaching retina. Resulting in badly blurred vision, double vision, sensitivity to
bright lights and change in color vision. One eye is often more seriously affected than
the other. It may be cause by chemical change in the lens. The exact cause is still
unknown, but there are many factors that can accelerate cataract formation.These include
an injury, either from a blow to the head or direct eye injury, other diseases exposure
to radiation of any kind (x-rays, microwaves, or infrared rays) long-term use of a
corticosteroid drug. A child may be born with cataracts or develop them at an early age.
These cataracts, called congenital cataracts, may be caused by a genetic disorder such as
down syndrome or from a condition the mother had during pregnancy such as German
measles.
The fourth type are other defects such as color blindness, photophobia or albinism. Color
blindness is a inherited vision disorder which is often found in male rather than in
female. Persons who have color blindness do not have one of the three cone cells which
are responsible for receiving either blue, green and red. Therefore, people with color
blindness are likely to confuse with red and green. But the condition is not serious
enough to connect with visual impairments. Albinism is a hereditary disease. It must be
pass thorugh from both parents, each of whom either has albinism or is a carrier of that
trait. Albinism affects the production of melanin(Winzer,379). A lack of melanin in the
retina, iris and choroid will cause the pupil to become in deep red color, the iris will
become in grey, light blue or pink. A person with albinism will also suffer from
photophobia, which is the extreme sensitivity to light. Bright light may decreases the
person's visual acuity and may blinds the persons with albinism.