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Hyperopia, or far-sightedness, refers to a refractive error that causes light to be focused behind the retina. Those with hyperopia typically have a more difficult time seeing up close than in the distance. However, if hyperopia is significant, it can also cause distance blur. Hyperopia can be corrected by glasses, contact lenses, or, in some cases, refractive surgery.
Myopia, or near sightedness, refers to a refractive error that causes light to be focused in front of the retina. Those with myopia have a more difficult time seeing things in the distance than close up. Myopia can be corrected by glasses, contact lenses, or, in some cases, refractive surgery.
Astigmatism refers to the eyes inability to refract light uniformly through different planes of the cornea. The cornea is shaped more like a football instead of the typical spherical or basketball shape. Essentially, an astigmatic eye has two prescriptions. Those with considerable astigmatism may experience shadowed images and in extreme cases even double vision. Astigmatism can be corrected by glasses, special toric contact lenses or, in some cases, refractive surgery.
Presbyopia refers to age related changes to the flexibility of the intraocular lens. It often occurs around, or after the age of 40. Presbyopia causes the blurring of near vision. Early signs of presbyopia often include an inability to read in low lighting or at normal working distance. Presbyopia can be overcome with reading glasses or special glasses called progressives or bifocals.
Keratoconus is a progressive weakening and bulging of the cornea that often begins in teenaged years and early 20s. Symptoms include fluctuating vision, increased glare, and continual dissatisfaction with glasses. Family history and frequent eye rubbing are often associated with the condition. Keratoconus can be treated initially with soft or hard contact lenses. The best way to slow progression is through a procedure known as cross-linking, in which UV light is used to strengthen the bonds within the cornea.
Amblyopia, or “lazy eye” is the most common cause of reduced vision in children. When one eye is turned in or out, or has a significantly higher prescription than the fellow eye, the brain essentially “shuts off” the poor-seeing eye. Children will usually not complain about their bad eye, as their brain has adapted to use only the vision out of the better-seeing eye. If this discrepancy is not discovered and treated, typically before the age of 8, the eye may never develop vision to its fullest potential. In rare cases, if both eyes have a significant uncorrected prescription that goes untreated, overall vision may never reach its potential and can preclude them from ever obtaining a driver’s license!
Strabismus refers to an eye that is turned in or out. Most commonly, it is first discovered in infants. If untreated, the eye can become lazy, and never develop adequate vision. Strabismus can be treated sometimes with glasses, or if more severe, by ophthalmologists who perform surgery on eye muscles to straighten out the turned eye. Strabismus can also develop later on in life, sometimes secondary to a vascular problem, aneurysm or even a tumor. Any sudden onset double vision should be evaluated by an eye care professional as soon as possible.
The macula is the part of the eye responsible for central vision. Any condition that damages this tissue can compromise vision. Macular degeneration can present in two forms; wet and dry. In the dry form, small deposits known as drusen, accumulate in the macular area and disrupt the integrity of visual receptors. There is no cure for dry AMD, but studies have shown there are several approaches to slow the progression of the disease. In wet AMD, blood accumulates behind the macula and causes rapid vision loss. The only way to treat this condition is to have an ocular injection administered.
Glaucoma is a condition that causes progressive “eating away” of the optic nerve, the electric cable that connects the eye with the brain. Glaucoma typically causes initial worsening of peripheral vision, and may progress to “tunnel vision” if left untreated. Glaucoma is often associated with elevated eye pressure. Fortunately, eye pressure can be lowered by taking specific eye drops or through surgical procedures. Because glaucoma is progressive and irreversible, routine eye exams are important for early detection and prevention.
When blood sugars stay elevated for an extended period of time, small blood vessels in the back of the eye become susceptible to bleeds. When these vessels leak, vision can become compromised. Significant diabetic retinopathy must be treated with laser or in some cases injections. Yearly eye exams are crucial for diabetics, to ensure eye health is stable, and to provide family doctors with an update on the appearance of small blood vessels.
Although often not as obvious as diabetic retinopathy, high blood pressure can also sometimes be detected with careful examination of the retina. Those with high blood pressure may show abnormal blood vessel in the retina. In more extreme cases, high blood pressure can lead to bleeds in the back of the eye.
A retinal detachment is a sight-threatening medical emergency. In this condition, the retina rips apart from its underlying tissue (much like ripping off wallpaper). Symptoms include, sudden “lightning bolt” flashes, dark spots floating over one’s vision, or a curtain or veil obstructing a portion of vision. Anyone experiencing one or more of these symptoms should have their eyes checked immediately by an eye care professional. Delayed treatment may result in permanent vision loss.
Sometimes white circles may develop around the cornea. This can be an indicator of elevated cholesterol levels and often warrant updated blood work. This is just another example of how eyes can tell us so much about your general health!