Astigmatism: Definition, Causes, Symptoms, Risk Factors and Treatment

1. Corneal Astigmatism

Corneal astigmatism refers to a type of astigmatism where the cornea of the eye, the window at the front of the eye that lets light in, is misshapen or deformed, causing blurred vision and disrupting the cornea’s ability to focus light onto the retina. Changes in the shape of the cornea from spherical to a more ovular, egg-like shape results in astigmatism. Corneal astigmatism is different from lenticular astigmatism because in corneal astigmatism only the cornea is misshapen, while the lens is still in shape. Corneal astigmatism is additionally more common than lenticular astigmatism, according to Better Vision Guide, an online information centre dedicated to vision correction surgery.

2. Lenticular Astigmatism

Lenticular astigmatism refers to a type of astigmatism where the lens of the eye, the part of the eye that provides additional magnification power and helps to focus light, is misshapen or deformed, interfering with the eyes’ ability to receive, bend and focus light onto the retina. The retina creates images from the light seen by the eye, and sends it to the brain through the optic nerve. The lens of the eye is also known as the crystalline lens. Although the symptoms of lenticular astigmatism are functionally identical to the symptoms of corneal astigmatism, lenticular astigmatism is a rarer condition.

1. Keratoconus

Keratoconus is an eye condition that causes the cornea, the thin surface area of the eye, to become bulged and conical in shape. Keratoconus disrupts some of the cornea’s functions in the eye, and causes blurred vision and photophobia, meaning sensitivity to light and glare from the sun and other surfaces. Keratoconus is a genetic condition that may also be caused by environmental factors. The way keratoconus changes the shape of the cornea may result in symptoms of astigmatism.

However, it must be noted that while all eyes with keratoconus have astigmatism, not all cases of astigmatism are caused by keratoconus.

2. Eye Injury

Eye injury refers to trauma or damage to the eye that may change how the structure of the eye works, which can lead to altered vision, including astigmatism. Eye injuries include corneal abrasions, scratches or foreign objects, which may result in viral or bacterial infections as well. Eye injuries become a cause of astigmatism when the eye injury has caused damage to the lens or the cornea, resulting in an unusual shape that may not be able to bend or reflect light onto the retina with the same degree of accuracy.

3. Age

Age refers to a person’s eye becoming older and possibly losing its full function over time. Aging may cause cloudy vision, puffy eyes and presbyopia. Ageing becomes a cause of astigmatism because the likelihood of getting astigmatism increases as the eye ages. Aging also increases the risk of becoming affected by eye conditions that may result in astigmatism or symptoms of astigmatism. Astigmatism commonly becomes worse with age as well.

4. Eye Surgery

Eye surgery refers to invasive surgical procedures performed on the eye in order to treat an eye condition, perform laser surgery, make cosmetic changes or for other reasons. Eye surgery is a possible cause of astigmatism, as the cornea may still be healing or had alterations during the procedure. Astigmatism caused by laser surgery is called residual astigmatism, according to Vision Centre, an American information centre on eye care and eye health topics.

5. Genetics or Family History

Genetics or family history refers to a genetic propensity a person may have towards certain health conditions or other personal factors, such as hair or eye colour, based on the genetic and medical history of their parents or grandparents. Genetic conditions can be a warning that a person is likely to have a health issue their parents once did. Genetics or family history becomes a cause of astigmatism because if a parent or other member of the family has or had astigmatism, there is a strong chance that person's children or descendants will too.

6. Eye Disease

Eye disease refers to many different conditions and medical issues that may affect the eyes, its vision and general functions. Eye disease can include conditions such as eye allergies, blepharitis, glaucoma, eye herpes or conjunctivitis. Eye disease becomes a cause of astigmatism because certain diseases may increase the risk of astigmatism forming in the eye.

1. Squinting to See Clearly

Squinting to see clearly refers to slightly closing the eyes when looking at an object or focus point in order to see clearly, as squinting allows less light into the eyes and makes the lens of the eye change shape in order to focus more clearly. Squinting to see clearly becomes a symptom of astigmatism because the eyes are trying to forcefully overcompensate for the lesser vision caused by astigmatism and other possible refractive errors.

2. Seeing Glares or Halos Around Lights at Night

Seeing glares or halos around lights at night refers to uncomfortably bright or direct light shining into the eyes when looking at a light source in a low-light environment, such as night-time. Seeing glares or halos around lights at night becomes a symptom of astigmatism because the disruption to vision that astigmatism causes also affects the eyes’ ability to perceive lights and glare, creating a distortion.

3. Headaches

Headaches refers to a painful, throbbing or dull ache in and around the head, eyes and frontal lobe. Headaches are a symptom of many different conditions, including eye conditions or other health issues. Headaches become a symptom of astigmatism when the eyes have been focused or squinting for a prolonged period of time, possibly causing other symptoms of eye strain and eye fatigue as well.

4. Eye Fatigue

Eye fatigue refers to eye pain, strain and headaches caused by prolonged periods of concentration on a single object or point of focus. Eye fatigue becomes a symptom of astigmatism because as the eyes focus more intensely to overcome the visual compromises caused by astigmatism, they become more exhausted and strained, causing an uncomfortable feeling in the eyes and possibly headaches.

5. Blurry Vision

Blurry vision refers to vision that is hazy or distorted. Blurry vision is a common symptom of astigmatism that is caused by the misshapen cornea or lens disrupting how light hits the retina. The retina is located at the back of the eye and has cells that transmit light to the brain via the optic nerve. If someone has astigmatism, the misshapen cornea or lens does not refract light to the retina properly, leading to blurry vision at near and far distances.

When do Astigmatism Symptoms Usually Occur?

Symptoms of astigmatism usually occur from birth onwards, according to Mayo Clinic, an American health clinic and information database. Early symptoms of astigmatism may not be obvious enough to be noticeable from a young age. A difficulty in diagnosing astigmatism early is that a child of a young age may not realise their vision is compromised or blurry.

What are the Risk Factors of Astigmatism?

The risk factors of astigmatism are genetics or family history, eye injuries or surgeries, abnormal corneal shape, age, other medical conditions and environmental factors. The risk factors of astigmatism are listed below.

• Genetics or family history: Genetics or family history is a risk factor of astigmatism because astigmatism can be inherited, and individuals with a family history of the condition may be at a higher risk.
• Eye injuries or surgeries: Eye injuries or surgeries are a risk factor of astigmatism because trauma to the eye or previous eye surgeries can increase the risk of astigmatism.
• Abnormal corneal shape: Abnormal corneal shape is a risk factor of astigmatism because certain conditions that affect the shape of the cornea, such as keratoconus or pellucid marginal degeneration, can increase the risk of astigmatism.
• Age: Age is a risk factor of astigmatism because, while astigmatism can occur at any age, it is more common in older adults.
• Other medical conditions: Some medical conditions, such as diabetes or thyroid disease, may be associated with an increased risk of astigmatism.
• Environmental factors: Environmental factors are a risk factor of astigmatism because prolonged use of digital devices, reading in dim light, and exposure to environmental irritants such as smoke or allergens may increase the risk of astigmatism.

What are the Astigmatism Complications?

Astigmatism complications are lazy eye, eye strain and poor night vision. The possible complications of astigmatism are listed below.

• Lazy eye: Lazy eye, also known as amblyopia, is an eye condition that may become a complication of astigmatism if the astigmatism is only affecting one eye, if one eye has worse distortion of vision than the other, and if the condition is not treated in time.
• Eye strain: Eye strain is an eye condition caused by prolonged focus on a single object or point of focus. Eye strain may become a complication of astigmatism because without treatment the eyes will fatigue and exhaust themselves trying to overcompensate for the visual issues caused by astigmatism.
• Poor night vision: Poor night vision refers to poor visibility and visual skill in dark or poorly lit environments. Poor night vision may become a complication of astigmatism because the deformed lens of the cornea caused by astigmatism can interfere with the eyes’ ability to perceive light, disrupting general sight as well as night vision.

How is Astigmatism Diagnosed?

Astigmatism is diagnosed by an optometrist or other relevant eye health professional by using a basic eye test to examine the eyes, and determining if there are any refraction errors that are causing blurred vision.a measure of what type of prescription you require or if a prescription is needed at all. A refraction eye exam enables the optometrist to evaluate how well your eye bends light as it passes through the eye and where the light lands in relation to your retina.

Can Eye Drops Treat Astigmatism?

No, eye drops cannot treat astigmatism, as there are no eye drops that can correct or change the shape of the lens or cornea currently available.

Will Wearing Glasses Correct My Astigmatism?

Yes, wearing glasses can correct and treat astigmatism. Eyeglasses are the most common treatment for astigmatism. Eyeglasses treat astigmatism as they contain cylindrical prescription lenses that will correct the focal disruption in the eye that is caused by astigmatism. Glasses for astigmatism are strictly prescription. Over the counter frames or reading glasses may not be effective in correcting the condition.

Will Contact Lenses Correct My Astigmatism?

Yes, contact lenses can help to correct astigmatism. Some people may need toric lenses to correct astigmatism, which are contact lenses designed specifcally for this vision issue.

Please note, Oscar Wylee does not sell contact lenses.

Does Wearing Glasses Every Day Prevent Astigmatism?

Wearing glasses will not prevent astigmatism or prevent the formation and causes of astigmatism in the eye. Wearing glasses every day, however, will allow a person affected by astigmatism to see clearly and avoid the uncomfortable and inconvenient symptoms of astigmatism, granting better daily vision and securing a better quality of life.