Astigmatism Tests: A Comprehensive Guide

What is an astigmatism test?

An astigmatism test is a group of eye examinations designed to detect whether you have astigmatism — a common vision condition that causes blurred or distorted vision.

These tests are typically part of a routine eye exam and help your eye care professional determine the shape of your cornea and lens, as well as the degree and type of refractive error present. Another reason your doctor may recommend an astigmatism test is if you have astigmatism symptoms such as blurred vision, headaches and eye strain.

What is astigmatism?

Astigmatism, a medical term, refers to the irregular shape of your eye, characterised by a higher degree of curvature than normal. This irregular shape causes a refractive error, where the eye fails to focus light evenly onto the retina, leading to blurred or distorted vision at any distance. 

Astigmatism is also an extremely common eye condition that affects people of all ages, often from birth, and may change over time.

What causes astigmatism?

An irregular curvature of the cornea or lens typically causes astigmatism. Instead of being perfectly round, the surface of your eye is shaped more like an oval or rugby ball, causing light to focus on multiple points in the eye rather than a single point.

The exact cause is often unclear but can be influenced by genetics, too much pressure on your cornea because of your eyelids, or the position of the eye in the socket.

Other causes can be keratoconus, a condition where your cornea thins and gradually bulges outward into a cone shape, and complications after an eye surgery.

What are some symptoms of astigmatism?

Some symptoms of astigmatism include:

• Blurred or distorted vision at all distances

• Double vision

• Seeing a glare or halos around lights

• Fatigue and headaches

• Eyestrain or discomfort

• Difficulty seeing clearly at night

• Squinting or frequent need to rub the eyes

How do astigmatism tests work?

There are multiple different astigmatism tests that involve several procedures to assess the shape of your cornea and the quality of your vision. Here’s how each test contributes:

• Refraction:

  • Refraction tests determine if you have a refractive error, including astigmatism. There are two types of refraction in an eye exam: an automated refraction (performed using a machine) and a manual refraction (performed by your eye doctor).

  • During the manual refraction, you will look at an eye chart as pairs of lenses are placed in front of your eyes, and you will be asked, “Which lens makes things clearer — lens 1 or lens 2?” (or something similar to that effect).

• Visual acuity test:

  • During your eye exam, your visual acuity, or how well you can see at various distances, will be tested with an eye chart. It can help gauge the severity of your astigmatism or other refractive errors.

  • This measurement will be performed while you wear your current eyeglasses (or without corrective lenses if you don't currently wear them) and then again after a manual refraction.

• Keratometry:

  • A keratometer measures the curvature of your cornea. Since astigmatism frequently results from uneven curvature along different parts of the cornea, this test helps quantify that difference.

• Slit lamp exam:

  • A slit lamp is a microscope with a bright light used to examine the front structures of your eye, including the cornea and lens, to detect irregularities that may cause astigmatism.

  • They will also adjust the brightness and thickness of the light's beam to see the different layers and parts of your eye.

• Retinoscopy:

  • During retinoscopy, your doctor uses a light beam and a series of lenses to objectively estimate the refractive error. This helps determine the prescription needed for corrective lenses.

• Autorefractors and aberrometers:

  • These automated instruments quickly measure how light changes as it enters your eye, providing an objective assessment of refractive errors, including astigmatism.

• Corneal topography:

  • This advanced test creates a detailed map of the corneal surface, revealing even subtle irregularities in the eye's shape that can cause astigmatism.

• At-home tests:

  • You can perform simple at-home tests using online charts or dials. These typically involve looking at patterns of lines and noting if some appear blurrier or darker than others, which may suggest astigmatism. However, these are not a substitute for a professional eye exam.

  • If you think you may have astigmatism based on these at-home tests, be sure to follow up with an eye doctor, who can confirm the assessment and help you find adequate treatments.

If you are unsure what type of test is suitable for you, don’t hesitate to request an appointment with Thomson Medical. Our ophthalmologists will help you to answer any questions you have and provide you with tailored recommendations.

How do I prepare for my astigmatism test?

There are no special preparations typically required for an astigmatism test. However, it can be helpful to bring your current glasses or contact lenses and inform your healthcare provider with a list of any symptoms you may be experiencing.

Before certain tests, your healthcare provider may ask you to remove your contact lenses if you wear them. Moreover, since astigmatism tests are non-invasive, they also carry no risks.

What do my test results mean?

Your test results will indicate whether you have astigmatism, how severe it is, and the best way to correct it.

The numbers on your glasses prescription will show the degree of astigmatism and the axis (direction) of the curvature difference. If you receive a diagnosis for astigmatism, your doctor may recommend one of many treatment options.

The most efficient treatment will depend on each unique individual case, so two people with astigmatism may receive different treatment recommendations based on the severity of their results.

How can I treat my astigmatism?

Some common treatment options for astigmatism include:

• Glasses:

  • This is the simplest and most common correction.

• Contact lenses:

  • Special toric lenses or rigid gas-permeable lenses can correct astigmatism.

• Refractive surgery:

  • Procedures like laser-assisted in situ keratomileusis surgery, more commonly known as LASIK, and photorefractive keratectomy (PRK) can permanently reshape the cornea.

• Orthokeratology (Ortho-K):

  • Special contact lenses worn overnight to temporarily reshape the cornea.

• Implantable lenses or cataract surgery:

  • For some patients, especially older adults.

How much are astigmatism tests?

Astigmatism tests in Singapore are generally included as part of a comprehensive eye examination or screening. The cost will vary depending on the clinic you go to, the type of tests performed, and whether you see an optometrist or an ophthalmologist. Examples include:

• Basic eye screening tests that include tests for astigmatism (such as visual acuity and refraction) can start from as low as $25 to $54 at optical shops.

• General eye screening packages at specialist clinics typically range from $99 to $256, often including visual acuity, refraction, and sometimes additional assessments like corneal topography or slit lamp examination.

• Consultations with eye specialists (ophthalmologists) are usually priced between $130 and $200 for a first visit, with additional charges for more advanced diagnostic tests if needed.

• Comprehensive eye screening packages with a wide array of tests (including those for astigmatism and other eye conditions) can cost up to $249 or more at some clinics.

If you require only a spectacles prescription test (refraction), the price can be as affordable as $30 at some optometry clinics.

Thus, you can expect to pay anywhere from $25 to $256 for astigmatism testing in Singapore, depending on the clinic and the comprehensiveness of the examination. More advanced or specialist consultations may cost more, especially if additional diagnostic procedures are required.

FAQ

How do I check if I have astigmatism?

You can check for astigmatism with at-home charts or dials, but a professional eye exam is necessary for a definitive diagnosis.

How can I reduce my astigmatism naturally?

There is no proven way to reduce astigmatism naturally. A healthy diet rich in vitamins A and C may support overall eye health but will not correct the underlying curvature. Consult your eye care professional before trying herbal remedies or supplements.

What happens if you ignore astigmatism?

Untreated astigmatism can lead to persistent eyestrain, headaches, and, in children, may contribute to amblyopia (lazy eye). It can also affect your ability to perform daily tasks safely.

Can you have 20/20 vision and still have astigmatism?

Yes, it is possible to have 20/20 vision and still have mild astigmatism, especially if the irregularity is minor and does not significantly affect your vision.

Should I wear my glasses all the time for astigmatism?

If your optometrist prescribes glasses for astigmatism, wearing them as recommended will help reduce symptoms and provide clearer vision.

Do glasses correct astigmatism?

Yes, glasses with specially shaped lenses can fully correct astigmatism by compensating for the uneven curvature of your cornea or lens.

What are the four symptoms of astigmatism?

Some common symptoms include:

• Blurred or distorted vision

• Eyestrain or discomfort

• Headaches

• Difficulty seeing at night

Can astigmatism be prevented?

There is no known way to prevent astigmatism, as it is usually caused by natural variations in eye shape. Regular eye exams can help detect changes early and ensure effective treatment.

The information provided is intended for general guidance only and should not be considered medical advice. For personalised recommendations and tailored advice, please consult a specialist at Thomson Medical. Request an appointment with Thomson Medical today.