|
Vision
Conditions Myopia | Hyperopia
| Astigmatism | Presbyopia
Eye
Health Conditions Cataracts
| Glaucoma | Macular
Degeneration | Diabetic Retinopathy
Click
here to view a diagram of the eye.
Vision
Conditions
Myopia
(Nearsightedness)
Myopia, or
nearsightedness, manifests as distant blur, while near vision remains relatively
unaffected. It's caused by the eye focusing an image short of the retina
at the back of the eye. If the eye is too long, or if the corneal curvarture is too strong, the light focuses in front of the
retina causing myopia.
Myopia is thought to be caused by genetics as well as prolonged near work
Myopia is very common and can be corrected with eyeglasses, contact lenses, or in some cases refractive surgery.
Top
Hyperopia
(Farsightedness)
Hyperopia (farsightedness) usually means that one has better distant vision
than near vision. It is very common. In fact, the majority of the United States population is
farsighted. The condition is characterized by an eye that is too short in length, or where
corneal curvature is too weak.
Most people can automatically compensate for their hyperopia by focusing more with their
lens. However, in cases of moderate to high hyperopia this compensation may not
be possible and the hyperopia must be corrected. Also, as we age, the lens
loses its ability to
focus. So, hyperopia may manifest itself when people get older and therefore must be corrected.
Hyperopia can be corrected with eyeglasses, contact lenses, or in some cases refractive
surgery.
Top
Astigmatism
Astigmatism is type of refractive error like
myopia (nearsightedness) and hyperopia
(farsightedness). Though astigmatism can occur by itself, it is most commonly found in combination with myopia or hyperopia.
Astigmatism occurs when the cornea is not perfectly spherical. It is a little longer in one direction than it is in the other. This creates two focal points for the eye.
Astigmatism can be corrected with glasses, contact lenses, or in some cases refractive surgery.
Top
Presbyopia
Presbyopia means "old eyes" in Latin.
The lens inside the eye is responsible for fine tuned focusing when performing near visual tasks. The
lens is
elastic and changes shape in order to focus. With the passage of time, the lens
looses elasticity and the ability focus becomes difficult.
Around the age of 40, we loose enough elasticity in our lens
to interfere with our ability to read within arm's length. To see clearly, it
becomes necessary to hold reading material further and further away.
Eventually, corrective devices that "focus" for us, become a necessity. The options are regular reading glasses, bifocals, trifocals, or
progressive or no-line bifocals.
Also, contact lenses can be utilized to correct presbyopia. Bifocal contact lenses are available
as well as monovision. Monovision is a procedure in which your dominant eye is corrected for
distance and your non-dominant eye is corrected for near.
Top
Eye Health Conditions
Cataracts
A cataract is a clouding of the normally clear
lens of the eye. It can be compared to a window that is
frosted or "fogged" with steam. Common symptoms of cataracts include a painless blurring of vision, glare,
light sensitivity, needing brighter light to read, poor night vision, and fading or yellowing of colors
Although the most common type of cataract is related to aging of the eye, other causes include family
history, medical problems (such as diabetes), medications (such as steroids) long-term unprotected
exposure to sunlight, and previous eye surgery.
Most cataracts associated with aging process gradually develop over a period of years while other
cataracts in younger people and people with diabetes may progress over a few months. It is not
possible to predict exactly how fast cataracts will develop in any given person.
Surgery is the only way to remove a cataract, however if symptoms are mild a change of glasses may
be all that is needed to function more comfortably. There are no medications, dietary supplements,
exercises, or optical devices that have been shown to prevent or cure cataracts. Sunglasses that screen
out ultraviolet (UV) light rays or regular eyeglasses with a clear, anti-UV coating can provide
protection from excessive sunlight, which may help prevent or slow the progression of cataracts.
Top
Glaucoma
Glaucoma is an eye disease that is one of the
leading causes of blindness in the United States. There are usually no symptoms
of glaucoma until very late in the disease. Glaucoma can produce damage to
the optic nerve of the eye, which carries visual information to
the brain, thereby causing blind spots in the field of vision. Glaucoma is
usually caused by the blocking of the drainage of aqueous humor (a clear
transparent liquid) that flows continuously through the eye. The name of the
structure where the aqueous humor drains is the
trabecular meshwork. When this gets
blocked, pressure within the eye is increased and can cause damage to the optic nerve. Blockage may be due to one of several reasons.
Glaucoma is usually treated and controlled with eye drops. These medications act
to decrease eye pressure either by assisting flow of fluid out of the eye or by
decreasing the amount of fluid entering the eye. Treatment should be monitored
regularly and may need to be changed periodically since glaucoma can get worse
without a person knowing it. Treatment also helps prevent further damage as well
as preserving existing vision. Surgical treatment for glaucoma is
available when medications don't prove effective.
Top
Macular
Degeneration
Macular Degeneration is one of the leading causes of legal blindness in the
United States. It is characterized by damage or breakdown of the
macula
of the eye. The macula
is the area on our
retina which gives us our
sharpest vision. When the macula
doesn't function correctly, we experience blurriness or darkness in the center of our vision. Macular
Degeneration affects both distance and close vision, and reduces vision in the central part of the retina
but does not effect the eye's side, or peripheral, vision. Macular Degeneration alone does not result in
total blindness.
The two most common types of age-related macular degeneration are "dry" and "wet".
Most people have "dry" macular degeneration, which is caused by aging and thinning of
the tissues of the macula. This vision loss is usually gradual. "Wet" macular degeneration accounts for
approximately 10% of all cases and is caused by abnormal blood vessels at the back of the eye. These
blood vessels may leak fluid or blood and blur central vision. Vision loss with "wet" macular
degeneration may be rapid and severe.
Although sometimes only one eye is affected and the other eye continues to see well for years, when
both eyes are affected central vision loss may be noticed more quickly. Signs of possible macular
degeneration in individuals may include a dark or empty area appearing in the center of vision
or straight lines look distorted.
Macular degeneration can be diagnosed during an eye examination. Despite ongoing research, there is no cure for macular degeneration, although "wet"
macular degeneration can be treated with laser surgery in its early stages.
Top
Diabetic
Retinopathy
The major cause of blindness in
people with diabetes is Diabetic Retinopathy. Diabetic Retinopathy is a term
used for all the abnormalities of the small blood vessels of the
retina caused
by diabetes, such as weakening of blood vessel walls or leakage from blood
vessels. Retinopathy progresses from non-proliferative or background retinopathy
to proliferative retinopathy.
Non-proliferative retinopathy is a common, usually mild
form that generally does not interfere with vision. Abnormalities are limited to
the retina and
usually will only interfere with vision if it involves the macula, the area on
the retina
that gives us the sharpest vision. If left untreated it can
progress to proliferative retinopathy. Proliferative retinopathy, the more
serious form, occurs when new blood vessels branch out or proliferate in and
around the
retina. It
can cause bleeding into the center of the eye or swelling of the retina
and lead to blindness. In severe cases of diabetic retinopathy, surgical
treatment is available which may improve sight or prevent any further loss of
vision.
Therefore,
it is important that all diabetics get an annual dilated eye exam to detect any
early signs of Diabetic Retinopathy.
Top
|
