What you need to know
The eye is the organ associated with normal vision. A healthy eye uses light to project an image to the pupil which focuses on the cornea. From there, the light moves through the lens and focuses on the retina. Then, the receptors present (rods and cones) react to pigments that cause synapses. These signals move through the eye to the optic nerve. It then travels to the brain (Goldstein, 2014).
An Astigmatic eye is a functional eye. It is caused by a curvature of the anatomy of the eye (Mayo, 2016). This causes light to refract on multiple areas of the retina. This makes the vision impaired.
Astigmatism has an affect on the perception of a subject. A healthy eye focuses light exactly and precisely, giving a clear image of the subject. Because of the structure of an astigmatic eye, the light doesn't focus which can give the subject a different view.
Mayo Foundation for Medical Education and Research (2016)
Anatomy of a healthy eye.
The Eye Practice (2015)
Visual difference between a healthy eye and Astigmatic eye.
Facial view of both a healthy eye and an Astigmatic eye.
Symptoms & Treatment
Astigmatism Test Info (2016). Retrieved from: http://www.astigmatismtestinfo.com/uncategorized/considering-lasik-after-your-astigmatism-test/
Goldstein, E.B. (2014). Sensation and Perception, 9th edition. Belmont: Wadsworth.
Mayo Foundation for Medical Education and Research (2016). Retrieved from: http://www.mayoclinic.org/healthy-lifestyle/adult-health/multimedia/anatomy-of-the-eye/img-20008178
The Eye Practice (2015). Retrieved from: http://www.theeyepractice.com.au/optometrist-sydney/treating-astigmatism-with-laser-eye-surgery