Understanding Astigmatism

Most of us have probably heard about astigmatism, but what does it really mean… 

Astigmatism (uh-STIG-muh-tiz-um) is a type of refractive error resulting in blurry, distorted vision.  Typically, someone with astigmatism may have trouble differentiating a “c” from an “o” or they may experience shadows around words or objects, often mistaken for double vision.  

Astigmatism is the result of an irregularly shaped cornea or lens – instead of the surface being perfectly round like a soccer ball, it is more oval-shaped like a rugby ball.  This irregularly shaped surface causes light rays to bend unevenly and focus on multiple points on the retina, instead of converging to one single focus point. 

Despite sounding rather serious, astigmatism is extremely common.  In fact, it is so common that the majority of eyes we test have some degree of astigmatism! 

Symptoms include:

• Blurred or distorted vision at all distances
• Ghost images
• Glare/haloes around lights
• Difficulty with night vision
• Eye strain
• Headaches

Causes:

• Genetics – Many cases are hereditary and passed down in families.
• Eye surgery – Certain eye surgeries, such as cataract surgery, may alter the cornea’s shape, resulting in post-operative astigmatism.
• Eye injury – Trauma, injury or even previous infections may result in scarring or alterations in corneal shape, resulting in astigmatism. 
• Physical pressure on the eye – Any physical pressure that is exerted on the eye may also alter the corneal shape, resulting in astigmatism.  This is particularly observed in cases of eye allergies, with the tendency to rub the eyes due to symptoms of itchiness or discomfort.  It is therefore VERY IMPORTANT to break the habit of rubbing eyes and rather turn to eyedrops to relieve allergic symptoms. 
• Keratoconus – This is an eye condition caused by progressive thinning and weakening of the cornea, resulting in irregular bulging of the corneal surface, leading to astigmatism. 

 Treatment:

• A low to moderate degree of astigmatism can be well-corrected by means of spectacle lenses or even soft contact lenses. 
• A high degree of astigmatism may require more extensive treatment by means of hard contact lenses or even surgical procedures to provide a more regular corneal surface.