Different types of prescription eyeglasses

Written by Timothy Gorman

Prescription eyeglasses are glasses that have been prescribed by an optometrist to be worn by someone who has been diagnosed with a certain eye condition. Depending onrepparttar condition, a different lens will be prescribed.

Prescription eyeglasses are broken down into four different categories.

The Single Vision Lens hasrepparttar 146150 same focal power fromrepparttar 146151 top ofrepparttar 146152 lens torepparttar 146153 bottom ofrepparttar 146154 lens. People who have been diagnosed as farsighted, nearsighted or with having astigmatism can wear single vision lenses to correct these types of eye disorders. Astigmatism is a condition that doesn't allow light to reflect onrepparttar 146155 retina, thus causing distorted images.

A Bifocal Lens is used to correct a condition call Presbyopia. This disorder usually occurs in people in their late 40's. If a person has been diagnosed with Presbyopia, they can't focus in on close objects. That is whererepparttar 146156 Bifocal Lens is helpful. The top ofrepparttar 146157 lens is used for distant vision andrepparttar 146158 bottom ofrepparttar 146159 lens is helpful with close vision. People with Presbyopia need both types of Focal View on their prescription eyeglasses.

How long have prescription eyeglasses been around?

Written by Timothy Gorman

From documents that were retrieved in Rome inrepparttar 13th Century, we know that prescription eyeglasses were available at that time. They were referred to as "spectacles" rather than glasses. Although we do not know for certain when prescription eyeglasses were invented, we do have proof that they did exist during this time period. A portrait done by an artist named Tomas da Modeno portrays a gentleman wearing eyeglasses. Obviously what we do not know is if they are prescription eyeglasses. There are, however, other documents such as a manuscript written by a man that implies that ifrepparttar 146149 he wasn't wearing spectacles, he would not be able to read or write.

Inrepparttar 146150 15th centuryrepparttar 146151 printing press was invented which meant more reading material was readily available. Thus,repparttar 146152 need for prescription glasses increased. The first reading glasses were held by one hand only duringrepparttar 146153 times that they were needed for reading. It was later inrepparttar 146154 17th century when people actually worerepparttar 146155 glasses regularly, after an optometrist created them with both earpieces. In those times, a person who was having difficulty with their eyesight would just go in and try on several pairs of prescription eyeglasses until they found a fit for their needs. That changed when Dr. FC Donders wroterepparttar 146156 first book on examiningrepparttar 146157 eyes to get prescription eyeglasses.

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