Eyeglasses, glasses or Spectacles, lenses mounted in frames to wear in front of the eyes to improve vision or to fix vision deficiencies such as myopia, hyperopia and astigmatism.

Ptolemy's description of lenses was commented upon and multiplied through Ibn Sahl (10th century) and most rather with the aid of Alhazen Book of Optics.  Latin translations of Ptolemy's Optics and of Alhazen became on hand in Europe in the 12th century, coinciding with the development of "reading stones".

Robert Grosseteste's treatise composed somewhere in the range of 1220 and 1235, makes reference to utilizing optics to "read the littlest letters at staggering separations" A couple of years after the fact in 1262, Roger Bacon is likewise known to have composed on the amplifying properties of lenses. The advancement of the principal eyeglasses occurred in Northern Italy in the second half of the thirteenth century.

Freely of the improvement of optical lenses, some cultures developed "sunglasses" for eye protection, besides any corrective properties. Thus, flat panes of smoky quartz, were used in 12th-century China. Similarly, the Inuit have used snow goggles for eye protection.

In Europe eyeglasses initially showed up in Italy, their acquaintance being ascribed with Alessandro di Spina of Florence. The fundamental illustration to exhibit eyeglasses is that of Hugh of Provence by using Tommaso da Modena, painted in 1352. In 1480 Domenico Ghirlandaio painted St. Jerome at a work area from which dangled eyeglasses; subsequently, St. Jerome turned into the supporter holy individual of the scene producers' society. 

The most punctual glasses had curved lens factors to assist farsightedness. A curved lens for nearsightedness, or partial blindness, is first clear in the picture of Pope Leo X painted by Raphael in 1517. 

Commonly utilized optical guides are eyeglasses (spectacles), and the specialized layout of eyeglass lenses has stepped forward impressively. A simple biconcave…

In 1784 Benjamin Franklin designed bifocals, keeping apart his lenses for near and distance vision, By the frame the split components being held together. Established bifocals had been designed in 1884, and the intertwined and one-piece sorts observed in 1908 and 1910, separately. 

Trifocals and new plans in bifocals had been later presented, inclusive of the Franklin bifocal restored in one-piece structure.

Lenses have been made of transparent quartz and beryl at the beginning, alternatively elevated activity brought about the appropriation of optical glass, for which Venice and Nürnberg were the central communities of creation. 

Ernst Abbe and Otto Schott in 1885 exhibited that the consolidation of new components into the glass soften prompted severa alluring types in refractive index and dispersive power.

In the contemporary process, glass for lenses is first rolled into plate form. glass for lenses is first folded into plate structure.

Most lenses are produced the use of clear crown glass of refractive index 1.523. In excessive nearsighted rectifications, a corrective enchantment is influenced if the lenses are made of thick rock glass (refractive list 1.69) 

and protected with a movie of magnesium fluoride to invalidate the surface reflections.

Which has much less dispersive power, is utilized in melded bifocals. 

Plastic lenses have gotten step by step mainstream, especially if the heaviness of the lenses is an issue, and plastic lenses are extra shatterproof than glass ones. 

In sunglasses, the focal lenses are tinted to reduce light transmission and remain away from glare.