Roman tragedian Seneca (4 BC–AD 65) is said to have read "all the books in Rome" by peering through a glass globe of water. A thousand years later, presbyopic monks used segments of glass spheres that could be laid against reading material to magnify the letters, basically a magnifying glass, called a "reading stone." They based their invention on the theories of the Arabic mathematician Alhazen (roughly 1000 AD). Yet, Greek philosopher Aristophanes (c. 448 BC-380 BC) knew that glass could be used as a magnifying glass. Nevertheless it was not until roughly 150 AD that Ptolemy discovered the basic rules of light diffraction and wrote extensively on the subject. (The laws of diffraction was formulated much later by Snellius, between 1600 and 1620.)

Venetian glass blowers, who had learned how to produce glass for reading stones, later constructed lenses that could be held in a frame in front of the eye instead of directly on the reading material. It was intended for use by one eye; the idea to frame two ground glasses using wood or horn, making them into a single unit was born in the 13th century.

In 1268 Roger Bacon made the first known scientific commentary on lenses for vision correction. Salvino D’Armate of Pisa and Alessandro Spina of Florence are often credited with the invention of spectacles around 1284 but there is no evidence to conclude this. The first mention of actual glasses is found in a 1289 manuscript when a member of the Popozo family wrote: "I am so debilitated by age that without the glasses known as spectacles, I would no longer be able to read or write." In 1306, a monk of Pisa mentioned in a sermon: "It is not yet 20 years since the art of making spectacles, one of the most useful arts on earth, was discovered." But nobody mentioned the inventor.

In the Middle Ages wearing spectacles signified knowledge and learning. Painters of the time often included spectacles when portraying famous persons even when depicting people who lived before the known invention of spectacles. On numerous paintings the religious teacher Sofronius Eusebius Hieronymus (340 - 420 AD) is portrayed with a lion, a skull and a pair of reading glasses. He is the patron saint of spectacle makers.

It actually is true that eating carrots can help you see better. Carrots contain Vitamin A, which feeds the chemicals that the eye shafts and cones are made of. The shafts capture black and white vision. The cones capture colour images.

The oldest known lens was found in the ruins of ancient Nineveh and was made of polished rock crystal.

In 1718, Edward Scarlett, a London optician, put arms on eyeglasses to hold them on the ears.

About one person in 30 is colour blind. More men than women are affected by colour blindness.

Healthy eyes are so sensitive to light that a candle burning in the dark can be detected 1,6km (1 mile) away. The human eye can distinguish about 10 million different colours. There currently is no machine that can achieve this remarkable feat.