Astigmatism is caused by an irregularly curved cornea, where one meridian is longer than the other. As a result, light entering the eye is not evenly focused on the retina, leading to blurred vision. This refractive defect occurs when light rays entering the eye are not refracted equally in all meridians, affecting vision at both near and far distances. Astigmatism is often associated with myopia or hyperopia. The irregular shape of the cornea is the most common cause, although it can also be caused by the irregular geometry of the lens.
- The irregular shape of the cornea.
- It is a hereditary condition.
- Eye trauma.
- A consequence of an underlying disease.
- Eye injuries.
- Unequal sharpness in horizontal, vertical, or oblique lines.
- Perception of distorted images.
- Blurred vision.
The diagnosis of astigmatism is made through a comprehensive visual examination that includes a series of tests to assess the condition of the eyes. These tests may involve shining bright lights into the eyes and using various lenses to determine the extent and nature of astigmatism.
More about astigmatism
What are the other causes?The primary cause of astigmatism is an abnormality in either the cornea or the lens. In cases of regular astigmatism, the meridians with the maximum and minimum curvatures are situated 180 degrees apart.
These types of astigmatism are relatively easier to correct. However, when the distribution of corneal curvatures is more irregular, the correction process becomes more complex. In such instances, astigmatism can have a pathological origin, resulting from an underlying disease or trauma.
While most cases of astigmatism are present from birth, there are also situations where this defect can develop later in life, such as after an injury or in conjunction with conditions like keratoconus or pterygium.
Types of Astigmatism
There are different types of astigmatism, classified based on the location and shape of the irregularity in the cornea or lens. Here are some of the most common types of astigmatism:
- Regular corneal astigmatism: in this type of astigmatism, the cornea has an irregular shape in two perpendicular directions, causing light rays to focus at two different points. This form of astigmatism can be corrected with corrective lenses.
- Irregular corneal astigmatism: in this type of astigmatism, the cornea has an irregular shape in multiple directions, causing light rays to focus at different points on the retina. This form of astigmatism can be difficult to correct with corrective lenses and may require surgery.
- Lenticular astigmatism: in this type of astigmatism, the irregular shape is found in the lens of the eye rather than the cornea. Lenticular astigmatism can be congenital or acquired and can be corrected with corrective lenses or surgery.
- Myopic astigmatism: this type of astigmatism occurs when the eye is myopic or nearsighted, meaning it has difficulty focusing on distant objects. Myopic astigmatism can be corrected with corrective lenses or surgery.
- Hyperopic astigmatism: in this type of astigmatism, the eye is hyperopic or farsighted, meaning it has difficulty focusing on nearby objects. Hyperopic astigmatism can be corrected with corrective lenses or surgery.
NEWS ABOUT Astigmatism surgery
Book your appointment