SEE IT!!! PART I

The Snellen Eye Chart

It's been reported that Seneca - the Roman statesman, dramatist, and philosopher (4 BC-65 AD) - used a glass globe filled with water as a magnifier to read "all the books of Rome." .

Around 1000AD

Around the year 1000, glass blowers in Italy are credited with producing reading stones made of solid glass. These devices were similar to hand-held magnifying lenses of today. The first vision aid was invented (inventor unknown) called a reading stone, which was a glass sphere that was laid on top of the material to be read that to magnified the letters.

1284

Italy, Salvino D'Armate is credited with inventing the first wearable eye glasses. This picture is a reproduction copied from an original pair of eye glasses dating back to the mid-1400's.

1600's

Spanish craftsmen create the first eyeglass frame temples. They attach ribbons of silk or strings to the frame and loop them over the wearer's ears. Spanish and Italian missionaries carry the new types of eyeglasses to China. The Chinese attach small metal weights to the strings instead of making loops.

1730

Optician Edward Scarlett introduces rigid temples that rest atop the wearer's ears.

1752

London medical instruments designer James Ayscough designs spectacles with double-hinged temples, which become widely popular. He also introduces green and blue tinted lenses to reduce glare.

1784

American Benjamin Franklin invents Bifocal lenses that have two specific powers---one for distance vision and one for near vision. Bifocal eyeglass lenses have the distance power in the top half of the lens and the near power in the bottom half of the lens. The near power consists of the distance power plus added magnifying power called the add power. In eyeglasses, the near power is located in the lower half of bifocal lenses.

1799

Scotsman John McAllister, Sr. opens the first optical shop in America in Philadelphia.

1800

The monocle (first called an eye ring) is introduced in England. Monocles remain popular in Europe among men in society's upper class throughout the 1800's.

1825

Englishman Sir George Airy designs the first lenses to correct astigmatism.

1826

Trifocal lensesLenses that have three specific powers---one for distance vision, one for intermediate vision, and one for near vision. The intermediate section typically has half the added magnifying power found in the near vision segment. Trifocals have two visible lines that cause image jump. Still, they are useful lenses for eyeglass wearers with advanced presbyopia who need a wide field of view for seeing objects at arm's length. Trifocal lenses are introduced by John Hawkins - inventor, musician, and engineer of London and Philadelphia.

1909

Dr. John Borsch, Jr. introduces fused bifocal lenses, making bifocals thinner and more attractive than Franklin-style bifocals.

1958

Essilor International of France introduces the first progressive multifocal lens, naming it Varilux.

Recent developments in optometry have resulted in corrective lenses conferring upon the wearer a vision of up to 20/10. Some birds, such as hawks, are believed to have an acuity of around 20/2; in this respect, their vision is much better than human eyesight. Many humans have one eye that has superior visual acuity over the other.

When are you declared legally blind?

If a person cannot achieve a visual acuity of 20/200 or above in the better eye, even with the best possible glasses, then that person is considered legally blind in the United States. A person with a visual field narrower than 20 degrees also meets the definition of legally blind.

Interested in checking your vision at home? Google: Snellen Eye Chart.

See ya!

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