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Prescription
Step 1
What is an astigmatism?
A spherical prescription means your eye will be rounder and the centre of the eye is in the centre of the eye. With an astigmatism your eye is more oval – at an extreme it is like a rugby ball. The centre of the of your eye can be located within a wide area. This means light is not directed to the centre of your eye.
Not focusing light into the centre of your eye can cause mild irritation to serious visual impairment depending of the size of your astigmatism. The Cyl refers to the extra power your prescription needs to help the astigmatism and the axis refers to the angle the light needs to be bent to reach the centre of your eye. The cyl can be written as + or a -. This isn’t an assessment of your or your eye’s attitude during the sight test, but two different ways optometrists can write a prescription – don’t ask me why, probably to look smart.
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