Index > > Purpose of Bifocals

Purpose of Bifocals

[Summary]Bifocals Bifocals with separate lenses Bifocals are eyeglasses with two distinct optical powers. Bifocals are commonly prescribed to people with presbyopia who also require a correction for myopia, hyperopia, and/or astigmatism. 4 Bifocals in the ani



Bifocals with separate lenses

Bifocals are eyeglasses with two distinct optical powers. Bifocals are commonly prescribed to people with presbyopia who also require a correction for myopia, hyperopia, and/or astigmatism.

4 Bifocals in the animal world

5 References

7 External links


Benjamin Franklin is generally credited with the invention of bifocals. Historians have produced some evidence to suggest that others may have come before him in the invention; however, a correspondence between George Whatley and John Fenno, editor of The Gazette of the United States, suggested that Franklin had indeed invented bifocals, and perhaps 50 years earlier than had been originally thought.[1] Since many inventions are developed independently by more than one person, it is possible that the invention of bifocals may have been such a case. Nonetheless, Benjamin Franklin was among the first to wear bifocal lenses, and Franklin's letters of correspondence suggest that he invented them independently, regardless of whether he was the first to invent them.[1]

A Trial of Bifocals in Myopic Children With Esophoria

About 25 percent of all persons in the United States are myopic. The most common form of myopia is childhood myopia, which begins after age 6 and progresses rapidly until age 16. Myopia progression results from excessive growth of the eye, primarily by enlargement of the vitreous chamber. Excessive elongation of the eye is a major risk factor for retinal detachment.

What are Bifocals? (with pictures)

Though most people who require bifocals have difficulty focusing on objects both up close and far away, they have always been designed with the corrective lens for close range focusing at the bottom and the corrective lens for distance vision at the top. While this design once made sense, because close range focusing was generally required for reading and writing, activities traditionally preformed while looking down, more and more people find it awkward to use such lenses with a computer. Since the computer monitor is directly in front of the user, the up close corrective lens seems out of place on some glasses.

[Editor: Admin]
Related for Purpose of Bifocals
  • Single Purpose Reverse MortgagesSeptember 29

    Reverse Mortgages: Avoiding a Reversal of Fortune | Update: The Department of Housing and Urban Development (HUD) recently made changes to Home Equity Conversion Mortgages (HECMs), which make up the majority of reverse mortgages in the U.S.

  • Purpose of a MemoSeptember 30

    Purdue OWL: Memos Audience and Purpose This handout will help you solve your memo-writing problems by discussing what a memo is, describing the parts of memos, and providing examples and explanations that will make your memos more effective. Contribu

  • What Is the Purpose of the American Cancer SocietySeptember 30

    American Cancer Society American Cancer Society Center Atlanta, Georgia The American Cancer Society (ACS) is a nationwide voluntary health organization dedicated to eliminating cancer. Established in 1913, the society is organized into eleven geograp

  • Purpose of the ConstitutionSeptember 30

    What is the purpose of the Constitution? | Full Answer The Constitution officially took effect on Sept. 17, 1787, during the Philadelphia Convention and has been amended 27 times since its adoption. The first 10 amendments of the Consti

  • Purpose of a GovernmentSeptember 30

    The Purposes of Government [] 1a. The Purposes of Government Why do governments exist? One major reason is that they create rules. But what rules are necessary or desirable? That is open to question, and different types of governments ha

  • 4 Major Purposes of GovernmentSeptember 30

    4 Major Purposes Of Government EDD Labor Market Information Division Labor Market Information. The Labor Market Information Division (LMID) is the official source for California Labor Market Information. The LMID promotes -

  • What Is the Purpose of the United Nations?September 30

    Chapter I | United Nations CHAPTER I: PURPOSES AND PRINCIPLES The Purposes of the United Nations are: To maintain international peace and security, and to that end: to take effective collective measures for the prevention and removal of threats to th

  • Purpose of Declaration of IndependenceSeptember 30

    United States Declaration of Independence The Declaration of Independence is the statement adopted by the Second Continental Congress meeting at the Pennsylvania State House (Independence Hall) in Philadelphia on July 4, 1776, which announced that th

  • Knife Blade Shapes and PurposeOctober 1

    Knife Blade Shapes Provides an overview of the main blade shapes and the advantages and disadvantages of each Blade Shapes Lansky Sharpeners :: Knife Blade Profiles and Uses If you took the time to read my last blog post, "Knife Edge Grinds and Uses&

Copyright Asdnyi All rights reserved.