Understanding Astigmatism: The Causes, Symptoms and Treatment

What is Astigmatism?

Astigmatism is a common vision problem caused by an imperfection in the shape of the cornea.

With astigmatism, the lens of the eye (cornea) has an irregular curve - those with astigmatism often have rugby-ball-shaped eyes instead of rounder, football-shaped eyes. This irregular shape changes the way light passes or refracts to your retina, causing blurry, fuzzy or distorted vision.

Astigmatism also occurs in conjunction with vision problems such as hyperopia (longsightedness) and myopia (shortsightedness).

Types of Astigmatism

There are actually two types of basic eye astigmatism: corneal and lenticular.

A corneal astigmatism is when there’s a defect or distortion in the cornea. Lenticular astigmatism is when there’s a distortion in the lens. Both can cause blurred vision, which can occur in more than one direction: horizontally, vertically or diagonally.

What Causes Astigmatism?

There isn’t a single cause of astigmatism. It can be hereditary and present from birth, or it can be caused by an eye injury, disease, or surgery where the cornea is damaged. It’s good to know that squinting or staring at a screen doesn’t cause or worsen astigmatism.

In rare cases, astigmatism can be caused by keratoconus, a disease of the cornea that causes the clear tissue to thin and bulge out, leading to blurry vision and light sensitivity.

Premature babies are also at risk of being born with astigmatism - this is because the cornea does not have enough time to fully develop before birth.

Astigmatism Symptoms

With astigmatism, vision is blurry and distorted. These aren’t the only astigmatism symptoms though. Others include:

• Difficulty seeing at night
• Eye strain and fatigue
• Squinting
• Irritated eyes
• Headaches

As mentioned earlier, astigmatism can exist alongside long- and short-sightedness, meaning you may experience several vision-related symptoms, like not being able to see far or near or having double vision.

What does astigmatism look like compared to normal vision? It can make objects near or far look fuzzy and out of focus. When driving at night, astigmatism can make the headlights and streetlights look smudged or distorted.

How is Astigmatism Tested?

If you suspect you have astigmatism, an optometrist or ophthalmologist can confirm whether you do with a comprehensive eye test.

There isn’t a dedicated astigmatism test but there are several that can be conducted to confirm diagnosis.

• Visual acuity test: This tests how well you can see the details of a letter or symbol from a specific distance. Your eye doctor will ask you to read letters from a chart to test your visual acuity.
• Refraction test: This test uses a machine called an optical refractor which has multiple corrective lenses at different strengths. The eye doctor will ask you to read a chart while flipping through these lenses to appropriately correct your vision.
• Keratometry: An instrument known as a keratometer will be used to measure the curvature of your cornea, which will help to diagnose astigmatism.

Treatments for Astigmatism

There are two main approaches to treating astigmatism: the use of visual aids like glasses and contact lenses or laser eye surgery. Astigmatism in mild cases doesn’t always need treatment, but it may need to be treated later if it worsens.

Getting corrective glasses or contact lenses is the least invasive way to treat astigmatism. Orthokeratology (Ortho-K) is a specific treatment method that uses rigid contact lenses to temporarily correct the irregular cornea shape. You wear these rigid contact lenses for limited periods of time, typically at night, until the curve of the eye evens out.

Can laser eye surgery fix astigmatism?

Yes, laser eye surgery fully corrects astigmatism, as well as other refractive issues like myopia and hyperopia.

There are several laser eye surgery treatments on offer to those with an astigmatism, including:

• Femto-LASIK: A thin flap is created in the cornea in order for it to be lasered and reshaped to correct the refractive error. The flap is closed and the eye heals within a matter of days.
• Trans-PRK: The tissue (epithelium) on the surface of the cornea is removed in order for the cornea to be reshaped with a laser. The epithelium grows back naturally.
• Refractive Lens Exchange (RLE): The eye's natural lens is replaced with an artificial one, correcting the refractive error.
• SMILE Pro: The cornea is reshaped with a laser, however, no flap is created but rather the ophthalmologist operates through a keyhole.

How Can I Prevent Astigmatism?

Unfortunately, there is no way to prevent astigmatism. The best way to manage it—or any other vision problem—is to schedule regular eye tests and take care of your eye health as best you can.

If you think you may have astigmatism, we can help you. Book your first consultation here or visit us at our shop in Westfield London White City (Sheperd’s Bush). We’re happy to answer any questions you have about astigmatism and laser eye surgery.