Lenses and Spectacles

The history of spectacles

The human face supplies us with an enormous quantity of information - and no other sense organ is more susceptible to disorders than the eye. Roughly 70% of Europeans have visual defects.Just think of all the things we wouldn't be able to do if we didn't have access to vision aids! Since the Middle Ages human knowledge has increased exponentially. It was during the Renaissance that both intellectual and technical developments surged ahead.

How was this possible?

One thing is certain, it was not only a handful of geniuses who began this initial development towards the information society we live in today. Rather the revolution came about due to the fact that increasing numbers of people could play an active part in the development. Two great milestones need to be mentioned in this context: firstly the invention of printing and also the invention of vision aids, or spectacles. Other inventions of the time were the microscope, telescope and the camera.

How far can the development be traced back?

In the ancient high cultures as far back as the Romans there were no spectacles. Marcus Tullius Cicero wrote to his friend Atticus-Cicero, one of Rome's great writers and statesmen (he died in BC 43), saying that now that he was old he had to have slaves read aloud to him as he could no longer read himself. Plinius reported that Nero watched the gladiator battles through an emerald. However, this was probably more for the pleasant effect of looking through a colour filter than to correct his vision. If we go back further to the ancient Chinese culture we read of glass that was used in the form of spectacles; the Chinese believed, however, that the poorly sighted were helped by the imaginary powers of "Yoh Shui".

So when did the first glasses appear as vision aids?

Drawings and paintings from the early cultures are a great help here. Many painters from the 15th century depicted biblical figures in religious paintings wearing spectacles. They showed life as it was in their own time and various objects providing useful historical clues for us today.

We are therefore not completely sure whether the religious teacher Sofronius Eusebius Hieronymus, who lived from 340 to 420 AD, was really the inventor of spectacles. On numerous pictures he is always portrayed with a lion, a skull and a pair of glasses. Because of this he is the patron saint of spectacle makers.

The Greek philosopher Aristophanes 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. Later, Roger Bacon, roughly in the year 1250 proved that people with poor eyesight could once again distinguish letters if they used ground lenses. However it was not until 300 years later that Snellius formulated the laws of diffraction between 1600 and 1620.

The monks of the Middle Ages developed the "reading stone" based on the theories of the Arabic mathematician Alhazen (roughly 1000 AD). This consisted mainly of rock crystal or semi-precious stones and it was ground into a hemisphere to magnify characters. The semi-precious stone was the virtually transparent beryllium.

At that time the only people capable of making transparent glass were the glass blowers of Venice. The first ground glasses were then made in the workshop of the famous Venetian glassworker Murano, and were initially only intended for one eye. Towards the end of the 13th century the idea was born to frame two such ground glasses using wood or horn, making them into a single unit. In the Middle Ages wearing spectacles signified knowledge and learning. It was not, however, until several centuries later (roughly 1850) that spectacles took on the form in which we know them today.

So now we know something of the history of spectacles.

What percentage of the population wears spectacles?

Roughly 70%.

That's a very high figure. What is the reason?

Apart from the many children and young people who are long or short-sighted, the ability to see near objects in sharp focus starts to deteriorate from the age of 25 meaning that from the age of roughly 40 many need their first vision aid, i.e. reading glasses.
Because the percentage of short-sighted people is increasingly rapidly and the population is ageing the percentage of spectacle-wearers is rising quickly.

Will a short-sighted person become long-sighted when they are older?

Age-related long-sightedness sometimes compensates for short-sightedness, especially in minor cases of short-sightedness, meaning that there is no need to wear reading glasses.

How do you notice if you have age-related long-sightedness?

You can no longer see small letters, or only with difficulty and with bright lighting. You may get headaches and the "arms grow shorter".

Are there any disorders which suddenly affect close-up vision?

Yes - high blood pressure (hypertonia), sugar diabetes (diabetes mellitus) and also certain types of migraine.

What types of vision aid are available?

Basically the ones already known: spectacles, contact lenses or surgical treatment.

Which types of spectacles are normally prescribed?

Children's glasses, long-distance glasses, reading glasses, work glasses, combined or "multi-focal" glasses.

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