MAJOR PROBLEMS VISUALS
Disease information
MAJOR PROBLEMS VISUALS
In order to be able to see or, it is needed that the images arrive clear and correctly to the brain so that can identify them and process, when this happens, says that the eyes are
normal
or emétropes.
But
when the images do not arrive from clear form because the light rays arrive at
a
center or place from the inadequate eye, take place distortions that
depend
on the ocular
problem
and to this abnormal eye is denominated to him or amétrope.
The main
problems
of
visual
sharpness are:
Myopia
. One appears when the light rays focus not directly in front of the
retina
and on her, causing who the near objects are seen easily,
but
the distant ones are difficult to distinguish. This
problem
must to
a
deformation of the ocular globe, that appears extended or because the crystalline
has
a
smaller focal length to the
normal
one and it is corrected with concave lenses that extend the focal length or with refracting surgery.
Hipermetropía, when the light rays project the image in
a
point behind the
retina
, causing that the near objects are blurred. This
problem
is caused by
a
cornea
or crystalline with little curvature or because the anteroposterior axis of the eye is shorter. One is made up with convex lenses that are heavier in the center that in the edges and shortens the focal length or with refracting surgery.
Astigmatism, happens when there is
a
deformation in several parts of the
cornea
, the membrane is transparent that it covers to the eye, causing that does not form
a
center on the
retina
,
but
a
generally incomplete or distorted confused image. The lenses that correct this
problem
are the cylindrical ones, that channels light rays towards
a
unique focal point. Also it is corrected with refracting surgery. This
problem
causes pains in the eyes and head and much eye
strain
.
Other
problems
that affect the vision are:
Presbiopía or presbicia. Also it is known him as "tired Vista" and is developed with the age. It is caused by the hardening of the crystallines, that lose something of elasticity. One generally begins to declare as of the 40 years and the person who suffers it must move away the small objects to be able to see them with clarity. She corrects herself with
eyeglasses
to see close by and / or different graduation in
each
eye, that she must
change
regularly until more or less the 65 years of age, when the
problem
generally no longer increases.
Color blindness or blindness to the colors, is
a
suffering that it prevents to the cones of the
retina
to distinguish all the colors or certain tones of color. The majority does not distinguish between the
red
one and green and the others cannot do it between tones of blue and
yellow
. Although it does not have cures for this
deficiency
, if the
problem
worsens, are possible to be suggested dyed
eyeglasses
to distinguish between the colors that are confused.
Ambliopía, also well - known like "syndrome of the sluggish eye or vague eye", is the partial loss of the vision of an eye. In rare occasions this
problem
can be presented / displayed both in eyes, with very clear signs of tremor or involuntary ocular movements.
It is caused mainly by the presence of estrabismo and the fixation of "the normal" eye. Another cause can be anisometropía, or difference of graduation from an eye to another one, which causes
a
delay of the
visual
capacity of the defective eye. Also it is caused by
congenital
cataracts.
Estrabismo:
Better well - known like "cross - eyed eyes". This suffering is characterized by the loss of the parallelism of the eyes, is to say that while one of the eyes watches an object, the other turns aside in another direction causing in many cases
a
showy aesthetic defect. This must to the alteration of muscles of the united eye to
a
bad vision mainly, that is to say, an eye is turned because it sees bad and sees bad because it is turned. The
problem
is corrected by means of the use of lenses with special crystals, the occlusion of the eye turned aside with patches,
muscular
exercises and in some things by means of surgery.
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