An Eye Full - A Look At Ophthalmology Terms

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An Eye Full - A Look At Ophthalmology Terms

 

Myopia (Nearsightedness)

 

Nearsightedness, or myopia, is a vision problem experienced by up to

about one-third of the population. Nearsighted people have difficulty

reading highway signs and seeing other objects at a distance, but can

see for up-close tasks such as reading or sewing.

 

Myopia Symptoms and Signs

 

Myopic people often have headaches or eyestrain, and might squint or

feel fatigued when driving or playing sports. If you experience these

symptoms while wearing your glasses or contact lenses, you may need a

comprehensive eye examination as well as a new prescription.

 

What Causes Myopia?

 

Myopia occurs when the eyeball is slightly longer than usual from

front to back. This causes light rays to focus at a point in front of

the retina, rather than directly on its surface.

 

Nearsightedness runs in families and usually appears in childhood.

This vision problem may stabilize at a certain point, although

sometimes it worsens with age. This is known as myopic creep.

 

Hyperopia (Farsightedness)

 

Hyperopia, or farsightedness, is a common vision problem, affecting

about a fourth of the population. People with hyperopia can see

distant objects very well, but have difficulty seeing objects that

are up close.Hyperopia Symptoms and Signs

 

Farsighted people sometimes have headaches or eyestrain, and may

squint or feel fatigued when performing work at close range. If you

get these symptoms while wearing your glasses or contact lenses, you

may need an eye exam and a new prescription.

 

What Causes Hyperopia?

 

This vision problem occurs when light rays entering the eye focus

behind the retina, rather than directly on it. The eyeball of a

farsighted person is shorter than normal.Many children are born with

hyperopia, and some of them " outgrow " it as the eyeball lengthens

with normal growth.

 

The hyperopic eye is shorter than normal. Incoming light focuses

behind, instead of on, the retina. Near objects look blurry to

farsighted people.

 

Sometimes people confuse hyperopia with presbyopia, which also is a

difficulty in seeing up close, but has a different cause.

 

Presbyopia

 

Those who lose the ability to focus on objects in the near range

including the ability to read fine print. The 40-and-over crowd is

finding that their arms are " growing shorter " as words become

difficult to see up close, and they must hold small items at arm's

length in order to be able to view them clearly.Called presbyopia,

this condition occurs as eyes gradually lose their ability to focus

on objects in the near range. But boomers have more choices than

their parents ever did when it comes to near vision

correction.Reading glasses are a popular option. With all sorts of

styles and colors, 40-somethings can have a pair for every room in

the house. And they work great as an adjunct to contact lenses

 

For some, segmented spectacle lenses, or multifocals with lines,

serve a specific purpose. Other presbyopes are flocking to no-line

bifocals, or progressive lenses, in droves now that there's no need

to reveal to the world that one is a bifocal wearer. These lenses

have more going for them than just good looks, though. They enable

the wearer to see at all distances, from far away to up close,

similar to the way that a person who doesn't need vision correction

focuses.

 

Macular Degeneration

 

Although many people are not aware of it, macular degeneration, often

called AMD or ARMD (for age-related macular degeneration), is the

leading cause of blindness in the world. The eye-health organization

Prevent Blindness America estimates that 13 million Americans have

evidence of macular degeneration.The disease breaks down the macula,

the light-sensitive part of the retina responsible for the sharp,

direct vision needed to read or drive. Central vision, especially, is

affected. Macular degeneration is diagnosed as either dry (atrophic)

or wet (exudative). The dry form is more common than the wet, with

about 90% of AMD patients diagnosed with dry AMD. The wet form of the

disease usually leads to more serious vision loss. Macular

degeneration is more common in people over age 65, and whites and

females tend to get the disease more than their counterparts. Most

cases of macular degeneration are related to aging. It also can occur

as a side effect of some drugs, and it appears to run in families.

Macular degeneration mainly affects central vision, causing " blind

spots " directly ahead.

 

Macular Degeneration Symptoms and Signs

 

Macular degeneration can produce a slow or sudden painless loss of

vision. If straight lines look wavy to you, your vision seems fuzzy,

or there are shadowy areas in your central vision, you may be

experiencing early signs of AMD.One way to tell if you are having

these vision problems is to view an Amsler grid, which is a chart of

black lines arranged in a graph pattern. Click here to see how an

Amsler grid works. Often, an eyecare practitioner will detect early

signs of macular degeneration before you experience symptoms. This

usually is accomplished through a visual field screening, a brief

test that measures your central vision. If the eyecare practitioner

detects some defect in your central vision, such as distortion or

blurriness, he or she will order a full visual field exam, a much

longer test that provides more extensive information about your

vision.

 

What Causes Macular Degeneration?

 

The exact causes of age-related macular degeneration are still

unknown. The dry form of AMD may result from the aging and thinning

of macular tissues, depositing of pigment in the macula, or a

combination of the two processes. With wet AMD, new blood vessels

grow beneath the retina and leak blood and fluid. This leakage causes

retinal cells to die and creates blind spots in central vision.

Factors that place you at a higher risk for AMD include having a

family member with AMD, smoking, high blood pressure, farsightedness

and obesity. Whites and females tend to get the disease more than

their counterparts.

 

Many researchers and eyecare practitioners believe that certain

nutrients — zinc, lutein, zeaxanthin and vitamins A, C and E — help

lower the risk for AMD or slow down the progression of dry AMD.

Dietary fat may be a factor as well. A study published in the August

2001 issue of Archives of Ophthalmology found that consumption of

omega-3 fatty acids, which are particularly prevalent in cold-water

fish, had a protective effect against advanced macular degeneration.

Meanwhile, consumption of omega-6 fatty acids, prevalent in vegetable

oils, was associated with an increased risk.

 

Some cases of macular degeneration are side effects of toxic drugs

such as Aralen (chloroquine, an anti-malarial drug) or phenothiazine,

rather than age-related. Phenothiazine is a class of anti-psychotic

drugs, including Thorazine (chlorpromazine, which is also used to

treat nausea and vomiting, and intractable hiccups), Mellaril

(thioridazine), Prolixin (fluphenazine), Trilafon (perphenazine) and

Stelazine (trifluoperazine).

 

 

Andrew Pacholyk, MS, L.Ac.

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