Bifocal Glasses

The invention of Bifocal lens is credited to the great American statesman and inventor Benjamin Franklin. The story of this invention dates back to 1784 at a time when Sir Benjamin Franklin was getting pale and old. The strength of his eyes was completely deteriorated. He was tired switching between close and distant lens and therefore he devised the bifocal lens. Bifocal glasses are glasses with two distinct optical powers. Each lens is divided into two parts- the upper portion of lens is a convex lens for viewing distant objects and the lower portion is affixed with a concave lens for close viewing, such as for reading purposes. Though Benjamin Franklin was the inventor of bifocal but the method of fusing the lenses together was developed by Louis de Wecker. It was later patented by Dr. John L. Borsch. The most popularly used bifocal glass is the D-segment which is 28 mm wide.

Bifocal glasses are usually prescribed to people suffering from presbyopia which includes both myopia (short sightedness) as well as hyperopia (far sightedness). Apart from correcting the error of both far sightednesses as well as near sightedness, bifocal glasses also suffer from certain disadvantages. Initially using bifocal glasses can lead to headaches and dizziness since the eye does not adapt itself immediately to the switching of within the same lens. With time either the user learns to move the head in accordance with suitability or moving the reading material to suit visionary preference. While working on computers, bifocal glasses do not adequately serve the purpose. This requires constantly buzzing into a screen or say, a monitor placed in front of you eyes which cause muscle fatigue. For this, a monofocal lens with one optical power is preferred. The current bifocal glasses also suffer from the drawback of limited field of vision. Research is continuing in an attempt to eliminate this defect.

Bifocal lens should strictly be adorned only when prescribed, or it can lead to perennial eye disorder. They are freely and abundantly available in the market with attractive eyeglasses frames. These glasses frames enhance the looks of the individual and refrain from giving a geeky look. They are widely available in the market and over the internet. Plenty of sites online are solely dedicated to the sale of these bifocal glasses. Bifocal glasses are common among elderly people who suffer from poor eye sight pertaining to their age. These are a kind of prescription glasses.