What is astigmatism? Understanding this common eye condition

Astigmatism develops when the cornea or lens has an uneven curvature. Instead of being perfectly round, the surface may resemble a rugby ball. This irregular shape affects how light enters the eye and how it focuses on the back of the eye (the retina).

Primary causes include:

• Inherited traits present from birth
• Eye injury or surgery
• Eye diseases like keratoconus
• Changes in the lens due to ageing or cataracts

There are two main types of astigmatism:

1. Corneal astigmatism: Caused by an irregular curvature of the cornea
2. Lenticular astigmatism: Due to imperfections in the eye's lens

An eye doctor can detect astigmatism during a routine eye exam. Testing typically includes:

• Visual acuity test
• Refraction test
• Keratometry to measure curvature of the cornea

These tests assess how well your eyes focus light and determine the degree of astigmatism.

Astigmatism and contact lenses

Astigmatism is easily corrected with the right vision aids. Contact lenses, particularly toric lenses, are a popular option. Toric contact lenses are specially designed to correct astigmatism by compensating for the irregular shape of the cornea and lens.

When prescribing lenses for astigmatism, eye doctors use two key values in addition to sphere power:

• Cylinder (CYL): the amount of lens power needed to correct the astigmatism
• Axis: the angle that shows the orientation of the astigmatism correction

These values ensure the lenses are tailored precisely to your eye, providing stable and clear vision.

• Provide clear vision
• Available in daily contact lenses, monthly contact lenses and extended wear contact lenses options
• Suitable for both mild and moderate astigmatism

Disposable lenses or monthly lenses with advanced moisture technology can offer better comfort and hydration, reducing eye strain.

If contact lenses or eyeglasses aren’t ideal, other corrective options include:

• Eyeglasses with cylindrical lenses
• Refractive surgery (e.g. LASIK or PRK)
• Lens replacement surgery for severe or irregular astigmatism

These treatments work by reshaping the cornea or replacing the lens to help focus light properly.

Children can be born with astigmatism, which may go unnoticed without regular eye exams. If untreated, it may cause lazy eye or learning difficulties due to poor vision. Annual eye check-ups are key for maintaining eye health and ensuring early intervention.

You should book an appointment with an optometrist or ophthalmologist if you notice:

• Persistent blurred or distorted vision
• Frequent headaches or eye strain
• Difficulty seeing at night

They’ll recommend treatment tailored to your eye condition and lifestyle.