Different types of eye disordersWritten by Timothy Gorman
The need for prescription eyeglasses could come from many different eye conditions. The most common eye disorders are Farsightedness, Nearsightedness and Presbyopia.
Nearsightedness, otherwise known as Myopia, is most common eye disorder. It occurs when light focuses in front of retina rather than focusing on retina. The symptoms for Myopia are blurred vision on objects that are in distance. Squinting eye will actually make object clearer. Vision can be corrected with prescription eyeglasses with either a bifocal or trifocal lens.
Farsightedness, or Hyperopia, is just opposite of Myopia. The light focuses behind retina instead of in front of retina. One common symptom of Hyperopia is headaches or eyes will become tired from reading. It is difficult to see objects that are within close range. In children, most common symptom is crossed eyes. Again this eye disorder, too, can be corrected by wearing prescription eyeglasses.
What are Prescription Eyeglasses made of?Written by Timothy Gorman
Prescription eyeglasses are manufactured in a variety of materials. The most basic is glass lens. The glass lens is by far best in absorbing ultraviolet light. It comes in several different colors and is, of course, scratch resistant. It is also one of least expensive. The downfall to glass lens is weight of a pair of prescription eyeglasses made of glass. They are also very breakable and have to undergo a heat-treated process to ensure durability.
Another material used to manufacture prescription eyeglasses is High-Index plastic lens. It also absorbs ultra violet light well. This type of lens is much lighter in weight than glass lens; however, they are also very expensive and can be scratched very easily.
Resin Plastic is another type of material used in manufacturing prescription eyeglass lens. They are lightest of all lenses, but do not offer high level of protection against ultra violet light that other lenses offer.