How Do The Eye Doctors Determine If You Have Astigmatism?
August 30, 2009 by admin
Filed under FAQ on advance for astigmatism
Astigmatism is the curved shape of the eye lens when it is not perfectly round. It usually looks a little football shaped.
The doctor will do a topology graph by light, non-contacting, that give an excellent picture. Of course it can be easily corrected with a lasik crowning while having your vision perfected.
It’s part of the basic refraction technique – that’s the part of the examination where they check what you can see on the chart and use different lenses.
There are a few ways to do it – the most common being the ‘crossed-cyls’ where you look at a chart and they ask you to compare 2 different lenses. The first stage of that finds the axis and the second does the power.
The other fairly common (although not as common IME) is the fan and block where you look at a chart that has two squares made up of lines and an arrow above it – the arrow is moved until it is clear to find the axis and then the lens is adjusted until both squares are equally clear.
Like I said though – it’s just something you do as part of the exam – not really an extra test even if you don’t have astigmatism.