 What Are Eyeglasses?
What Is an Eye Exam?
What Are The Lenses Made Of?
What Types of Vision Problems
What Can Cause Vision Loss Among the Elderly?
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Eyeglasses are frames bearing lenses worn in front of the human eyes normally for
vision correction or eye protection. Modern glasses are typically supported by pads on
the bridge of the nose and by temples placed over the ears.
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Sight is an amazing process. Light enters the eye and is bent or refracted by the cornea
(the window of the eye) through the pupil (the opening in the iris). The light passes
through the lens (located behind the pupil). This completes refraction by fine tuning
the focused light onto the retina. The retina changes the light (energy) into electric
impulses that are carried through the optic nerve to the vision center (occipital cortex)
of the brain where the image is interpreted.
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A comprehensive eye exam is how the PrimeSource Optometrist determines
a person’s vision and eye health. The eye doctor also checks to see if a person needs
glasses and tests the health of the eyes to make sure that she/he does not have
any other eye problems.
During the exam, the Optometrist will check if the patient is nearsighted, farsighted, has
an astigmatism or needs reading glasses. The patient will read an eye chart to test vision, then look through a special instrument while the doctor places lenses in front of her/his eyes to determine the correct prescription for glasses. The doctor will also use this instrument to test a person’s reading vision, focusing power, and how well her/his eyes are working together.
Next, the PrimeSource Optometrist will check the person’s eye health. The doctor uses a
special type of microscope to carefully check the front parts of the eye. Problems like
cataract or pink eye can be seen through the microscope. The doctor will measure the
amount of fluid pressure in the patient’s eyes to test for glaucoma. The Optometrist may
use special eye drops to dilate the pupils. This opens up the pupils so that the doctor can see the retina and optic nerve, and check for serious problems like retinal detachment and macular degeneration. Symptoms of some health problems such as diabetes and high blood pressure can also be seen in the eyes.
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Lenses are usually made from plastic, glass or polycarbonate.
Plastic, the most often used material for lenses, is impact resistant
and lightweight but scratches easily. Glass is still used for lenses
and is scratch resistant but heavy and breakable.
Most PrimeSource lenses are plastic. Glass and polycarbonate
lenses are available for an additional charge. Lenses can also be
upgraded with UV filters, tints and photochromics (all available
for additional charges).
Do Eyeglasses Correct?
Eyeglasses fitted with corrective lenses are a common means of
correcting focus problems such as myopia (nearsightedness,
shortsightedness) and hyperopia (farsightedness, longsightedness).
• Myopia is a condition in which parallel rays of light entering the eye converge before reaching the retina.
• Hyperopia is a condition in which parallel rays of light entering the eye do not converge prior to reaching the retina. Some would say “the rays of light converge at an
imaginary point behind the retina.”
• Astigmatism is a condition in which parallel rays of light entering the eye converge at two separate locations, either before or after the retina. As most people age, the crystalline lens of the eye loses elasticity resulting in presbyopia, which limits their ability to focus on nearby objects. None of these conditions is considered a disease.
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The most common causes of vision loss among the elderly are:
• Age-Related Macular Degeneration (illustrated at right) is a common eye disease that gradually destroys sharp, central vision and may lead to a loss of vision in one or both eyes.
• Cataract is a clouding of the eye’s lens that causes loss of vision. The prevalence of cataract is approximately 50 percent in people 75 years and older.
• Diabetic Retinopathy (illustrated at right) is a complication of diabetes and a leading cause of blindness. It occurs when diabetes damages the tiny blood vessels inside the retina, the light- sensitive tissue at the back
of the eye.
• Low vision is a permanent loss of visual acuity or perception due to eye diseases or eye injuries. Low vision usually can not be improved by eyeglasses. Different degrees
of low vision range from minuscule visual impairment to blurry vision to being almost totally blind. People with low vision sometimes lose the ability to drive, read, move about, and even distinguish different colors.
• Glaucoma (illustrated at right). An eye disease in which the normal fluid pressure inside the eyes slowly rises, leading to vision loss or even blindness. This disease affects 2.2 million Americans, half of whom are unaware they have it.
Risk increases with age. Regular eye examinations by a PrimeSource Optometrist are critical. Cataracts need to be monitored and eventually removed. Glaucoma, macular
degeneration and diabetic retinopathy all sneak up on their victims, destroying vital eye cells before the person is aware there’s anything wrong.
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