So, you’re off to the opticians for an eye test. If it’s
your first test for a while you might be a little bit nervous about what will
happen and the process that you will be going through. In a modern eye test
there are many different charts and tests that you will see as part of your eye
test, but they all had to be invented by someone, so this blog is to give you some background information about what
the tests are, but also a little bit about where they all came from.
The Eye Test Chart
You are probably familiar with the standard Snellen Eye
Chart, but what you probably didn’t know is that the first eye charts as we
know them were designed in 1843 by Heinrich Kuechler in typical German
efficiency in order to make the first attempt to standardise the charts to be
used. There was an update to these first charts in 1854, but it was the Dutch
ophthalmologist Herman Snellen who, in 1862, invented the test chart that is so
familiar today. You might be wondering what was different about Snellen’s
chart. It was all about the font, Snellen chose a square font so that letters
had the same height and width, which reduced variations in performance.
The Ophthalmoscope
The ophthalmoscope is the small hand held device that an
optician uses to shine a light into your eye to look at the back of your eye
and also at the lens. In order to do this a beam of light is shone into the eye
so that the optician can see the various structures. By changing the angle that
they look at your eye your optician can spot abnormalities or any signs of
disease. The very first ophthalmoscope was actually invented by Charles Babbage
in 1847, who is rather better known for inventing the first mechanical
computer. Although his ophthalmoscope was perfectly good, his sales skills
failed him and his invention was forgotten. Only 4 years later Herman von
Helmholtz, another renowned scientist and physician of the day, invented his
own version of the ophthalmoscope and clearly made a much better job of
marketing his device as it was used as part of eye tests until around 1920.
Glaucoma Tests
Intraocular pressure, or the pressure within the eyeball, is
an important parameter to measure to monitor as a sign of glaucoma presence.
Intraocular pressure has been highlighted since Sir William Bowman’s
presentation to the British Medical Association in 1826. At this stage though
the measurement was literally made by hand with the optician making their
assessment of the pressure by palpating the eyeball with their fingers!
Fortunately technology has come a long way since then through contact
tonometry, where a mechanical device pressed onto the eyeball to measure the
pressure, to the current practice of non-contact tonometry that makes the
measurement by using a puff of air blown onto the eyeball. There are also other
tests that are carried out to make more definite diagnoses of glaucoma as it is
not a simple disease.
So, now you know more about eye tests and where the
practices have come from why not head down to your local branch of
Specsdirect2u to make your free eye test appointment to make sure that your
eyes are in tip top health. We also offer free home eye tests if you live in the Glasgow area, call us today on 0141 554 8886 to make an enquiry.
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