The most common eye problems in America are refractive disorders. That means nearsightedness, farsightedness and astigmatism combined are to blame for most of the country's diminished vision. So what are these refractive errors? How can you prevent them? How do people live fulfilling lives with these conditions?
Nearsighted Vs. Farsighted - The Basics
Myopia, or "nearsightedness" is when light enters the cornea and is refracted, or "sent" to a spot in the eye before reaching the retina. In other words, when the cornea and lens receive light waves, they send it to the wrong place in the eye, usually because of the shape of the eyeball. This causes a person to be shortsighted, meaning able to see objects clearly up close, but unable to focus on items further away.
Hyperopia, also called "farsightedness" is similar. The light is refracted to a place beyond the retina, so that items far away are clear, but activities like reading and knitting are difficult, because nearby objects appear fuzzy or unfocused.
Astigmatism is another refractive error, distorting objects both near and far, so that everything appears out of focus and skewed.
Understanding Your Prescription
When you're diagnosed with either nearsightedness or farsightedness, you're given a degree to which you're affected, and a prescription. Both can seem equally confusing, since they involve numbers. First, keep in mind that your eyes may have differing degrees of myopia or hyperopia. So when you see "OD" or "OS" on your prescription, that refers to "right eye" and "left eye" respectively.
Next comes a number. This is the number, in diopters, of power a lens needs in order to sharpen images for you. If it's a negative number, you're nearsighted. Although, having lived with the condition for a while, this may come as no surprise. What may be enlightening though, is how much you're nearsighted. The more negative that number, the deeper your refractive error.
On the flip side, your number may be positive. If you have a plus number, you are farsighted. Similarly, the larger your number, the greater your need for correction. The measurement of standard is usually 20/20.
If you're reading from left-to-right, next comes the number, in diopters, to correct your particular level of astigmatism. Again, there will be a number (or at least a space for one) for each eye, since levels will vary from eye to eye.
In short, your prescription can cover all refractive bases, so to speak, telling your optician exactly what you'll need to see clearly.
Deciding on Treatment
Talking with your doctor is the best way to decide which corrective route to take. You may love the look and versatility of glasses, or you may want a more permanent option with vision correction surgery. If you prefer having the daily choice of both glasses and contacts, you'll need a prescription for each, since they won't be the same. Your prescription for contacts, which can only be obtained after a special appointment for fitting contacts, has more information on it, like the diameter and base curve of the lens. Also, the corrective power may vary, since glasses sit about 12 millimeters away from your cornea and your glasses are much further away.
Another option may be LASIK, a quick outpatient procedure that reshapes your cornea to offer you sharp vision indefinitely. To determine if you are a candidate for LASIK, special testing will need to be performed and evaluated by your doctor.
Since your prescription is only valid for a year, you'll want to stay current on your regular checkups. Not only will this ensure your sharp vision, it'll also help you prevent and treat common disorders before they have a chance to disrupt your vision.
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