Written on Mar 3, 2009 at 10:02 PM by LASIK Guider
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The majority of peoples suffering from prefer to wear eyeglasses to correct their vision. This preference for eyeglasses as a way to correct refractive errors, come from being low in cost and require no special care.

Eyeglasses

On the other hand, eyeglasses have some disadvantages. Eyeglasses may cause skin irritation and discomfort due to its heavy weight, especially in persons with high degrees of refractive errors, requiring thick corrective lenses.



Additionally, the peripheral vision with glasses is poor and in some prescriptions, the images may appear larger or smaller than its real size. Eyeglasses also, change the look of the person and are not suitable for certain occupations such as actors and sport athletes.



As a result, many people prefer to use or to undergo refractive surgeries such as to correct their vision.




How Eyeglasses work?

The lenses inside the glasses frames can be specially designed to correct various types of refractive errors such as , and . The target of these corrective lenses is to adjust the received image, allowing the eye to focus a sharp image on the retina at the back of the eye.




Materials used in the Making of Eyeglasses

Eyeglasses frames are made from plastic, tortoise shell or metals such as stainless steel, gold, aluminum and nickel, while the lenses inside the frames are made from either glass or plastic.

lenses

Advantages of plastic lenses
  • Lighter (nearly ½ the weight of glass lenses)
  • Do not fog easily with changes in temperature
  • Can be coated or dyed to reduced annoying reflections or to prevent scratches
  • Safer, but not unbreakable
Disadvantages of plastic lenses
  • Scratch easily, especially with regular old plastic lenses
  • Deformed on heating or under pressure

Eyeglasses lens Designs:

Multiple lens designs are available nowadays to choose from according to your needs and your eye doctor guidelines. The main available designs are:


Bifocal Eyeglasses

Single Vision Lenses are lenses with one focal power, as the whole lens is made from one prescription, it can be used only for correction of either distant vision or near vision, according to the prescription.



Multifocal lenses are lenses with more than one focal power. Various types of these lenses are available:

  • Bifocal lenses are lenses with two focal powers. It can be used for correction of both distant and near vision (e.g., reading) in the same lens (i.e., same pair of glasses). Bifocal Lenses
  • Trifocal lenses are lenses with three focal powers. It differs from bifocal in having an intermediate zone to compensate for the region where vision cannot be obtained through either the distance part or the near part of the lens. Trifocal Lenses
  • Varifocal lenses (progressive multifocal lenses) are lenses with progressive change of power from top to bottom. Objects at different distances can be seen clearly by looking through the suitable part of the lens.
Multifocal Lenses


The full series of LASIK Vision Correction Explained tutorials are , , , ,, , , , and .

2 comments:

Eyeglasses May 8, 2009 at 3:25 AM  

This is very helpful. Thank you for the information.

LASIK Guider May 9, 2009 at 1:19 AM  

@Eyeglasses
Thanks for your visit & comment

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