Astigmatism occurs when your cornea is shaped like a football. With astigmatism, more than one focal point within the eye distorts what you see. As a result, you experience a tilting of images due to the unequal bending of light rays entering your eyes.
Many patients with myopia and hyperopia have some degree of astigmatism, or an oval shape, to their cornea. People with high degrees of astigmatism have blurred vision for both near and distant objects.
Below are the categories of severity for astigmatism:
- Mild Astigmatism < 2.00 diopters
- When astigmatism measures between zero and 2.0 diopters, the patient is classified with mild astigmatism. Generally, an astigmatism severity of 1.5 or higher will require some correction. Patients in this category may not notice any symptoms, though some will experience blurry vision and occasional eye strain.
- Moderate Astigmatism 2.00 to 4.00 diopters
- A measurement of 2.0 to 4.0 diopters is usually classified as moderate astigmatism. These patients will often have blurry vision at a distance, resulting in other symptoms such as squinting, eye strain, and headaches.
- Severe Astigmatism 4.00 to 6.00 diopters
- A measurement of 4.0 to 6.0 diopters is usually classified as severe astigmatism. These patients often have distorted and blurry vision, difficulty focusing, and other related symptoms, including headaches and eye strain.
- Extreme Astigmatism > 6.00 diopters
- A measurement exceeding 6.0 diopters is classified as extreme astigmatism. These patients will usually have extreme difficulty seeing, including impaired night vision, significant distortion, and chronic discomfort.
