The Miracle of Sight — Common Eye Conditions and Treatments
This article is part two of a series that explores the wonderment of
eyesight, the care and keeping of eyes, common eye ailments and treatments, the
future of eye care and the emerging hope for the blind.
Chances are you know more people who need corrective lenses or other eye
treatments than people who don't. That's because normal vision, also called
emmetropia, is the result of many factors working together in perfection,
forming a sort of optical stellar alignment. In more scientific terms, light
entering the eye through a well-formed cornea focuses precisely on the retina,
resulting in an image that is sharp and bright. For many of us, however, the
tiniest misalignment or imperfection causes blurred vision, or even some
progressive conditions.
Common refractive problems
Emmetropia is a state in which the eye focuses light properly on the retina
without refractive error, without accommodation, and without correction.
The most common vision problem experienced in the U.S. is the inability to
focus incoming light precisely onto the retina, which can cause several
different conditions. Myopia, known as nearsightedness, occurs when the eyeball
is too long from front to back or the cornea is too curved. People with myopia
can see close objects clearly, but objects at a distance look blurry. Myopia
tends to be hereditary, developing at around age 12 and progressing until about
age 20. Rarely does the condition get any worse after age 30 and, in fact,
sometimes it improves with age. Hyperopia, also called farsightedness, occurs
when the cornea is too flat and/or the eye is too short. People with
farsightedness can see distant objects clearly, but can't see up close. This
condition is also hereditary.
Astigmatism is caused by a defect in the curvature of the cornea, or lens of
the eye. Most people with astigmatism have difficulty with peripheral vision.
Eyeglasses or contact lenses can correct myopia, hyperopia and astigmatism.
People with these conditions can also consider refractive surgery, such as
LASIK or photorefractive keratectomy.
Age and reading glasses
As we age, the eye lens hardens and the muscles around the eye become less
flexible. This loss of accommodation, or ability of the lens to change focus,
is called presbyopia. It typically begins after age 40 and is the likely reason
many older people need bifocals or reading glasses to see up close.
Glaucoma and Cataracts: Thieves of sight
Glaucoma is an eye disorder caused by increased fluid pressure within the
eyeball. It is most common in people over age 40 and is a leading cause of
blindness in people over 60. In about 90 percent of glaucoma cases, vision
deterioration is so gradual and painless that people barely notice the symptoms
until it has already done permanent damage. Glaucoma symptoms include foggy or
blurred vision (peripheral vision is usually affected first), difficulty in
adjusting to brightness and darkness, slight pain in or around the eye and a
halo effect around distant lights. If detected early, glaucoma usually can be
controlled with eyedrops, or laser surgery can also be used.
A cataract is a clouding of the lens of the eye that results in blurry
vision. Symptoms include sensitivity to light and glare, fading or yellowing of
colors, poor night vision and halos around lights. The exact cause of cataracts
is unknown, though aging is thought to play a role, since about half of
Americans between ages 65 and 74 have them. Cataracts are removed by the
minimally invasive use of an ultrasonic handpiece. A surgeon then implants an
artificial lens (intraocular lens) to replace the natural crystalline lens that
had become clouded by the cataract, a treatment that restores vision in about
98 percent of people. However, if left untreated,
cataracts can lead to blindness.
Macular degeneration
In this condition, deterioration occurs in the macula, the small central
part of the retina. Macular degeneration is the leading cause of central-vision
loss among people over age 60. Visual loss is progressive, though it does not
typically lead to total blindness. There are many treatment options that can
slow the progression of this disease, but no cure as yet.
Retinitis
Retinitis is an inflammation of the retina. It can have many causes,
including hereditary conditions and infections. Symptoms include night
blindness, inflammation of the retina,
tunnel vision and loss of sense of body movement. Treatments for this
condition vary and depend on the cause. If you have any of these symptoms, you
should visit an eye-care professional right away.
See a specialist
Early diagnosis of an eye condition can improve the chances for a successful
treatment.
Not sure what kind of specialist to see? Opticians are trained to make and
fit prescription eyewear, but not to diagnose eye conditions. Optometrists can
diagnose conditions and opthamologists are medical doctors who can prescribe
medicine and perform eye surgery.
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