In simple terms, astigmatism is an imperfection in the curvature of your eye’s cornea. This hinders your eye’s ability to focus light onto your retina, resulting in blurred and distorted vision. Fortunately, the condition is minor and can be corrected easily through the use of toric contact lenses.
Where a normal eye refracts light equally across all of the eye’s ‘meridians’ (imaginary lines across the surface of the eye), an eye with astigmatism means that light will be refracted more in one meridian than the other, distorting the light and the focal point it reaches.
The image below depicts the differences between a normal eye and one with astigmatism. As illustrated, light beams aren’t refracted properly by the astigmatic cornea, resulting in distorted focal points in front of and/or behind the retina.
This translates to blurred and hazy vision, which can also cause general discomfort. If not treated with toric contact lenses or glasses, astigmatism can result in headaches and eye strain.
Astigmatism can be either regular or irregular.
With regular astigmatism, the cornea of your eye is more curved in one particular direction than the other. The principle meridians of your eye are 90 degrees apart, perpendicular to each other.
Irregular astigmatism, however, is when the curvature isn’t an even curve across the surface of the eye. It can also be curved in multiple directions, or can be steeper towards the bottom.
Also, astigmatism can be one of three types depending on the visual complications it creates: