Astigmatism is a refractive error condition that causes blurry or distorted vision. It occurs because the cornea or lens in the eye has an irregular curvature, meaning the eye cannot focus light properly on the retina and results in blurring vision, near and far.
Astigmatism is characterised by varying amounts of short-sightedness and far-sightedness in different meridians of the eye (connecting circles on the front of the eye).2 This creates two points of focus within the eye that need correcting, often known as ‘rugby ball shape’, and can be easily corrected with glasses or contact lenses for astigmatism.
Myopia (short-sightedness) is a refractive error, meaning there is a problem with focusing light accurately onto the retina.
Myopic astigmatism is a condition in which one or both meridians in the eye are myopic. This means that the light rays are brought to focus in front of the retina instead of on the retina. When both meridians are myopic, there is a differing degree of near-sightedness in each.
Standard soft contact lenses correct the refraction errors but do not correct astigmatism. Toric contact lenses are made to specifically correct vision for astigmatism and are designed to stay properly oriented on the cornea.
Hyperopia (long-sightedness) is another refractive error in which the light rays focus behind the retina instead of on the retina. This makes it difficult to see objects up close, such as a book or computer screen.
When someone has both hyperopia and astigmatism, they need cylindrical lenses to correct the astigmatism (toric lenses), and also spherical lenses to correct the hyperopia.
When one meridian is myopic and the other is hyperopic, it is called mixed astigmatism.
What are toric contact lenses?
If you have been diagnosed with astigmatism, your optician may recommend that you need toric contact lenses. These contacts are designed to correct astigmatism, are very common and are available in different wear schedules, such as daily, weekly, monthly and yearly replacement hard lenses.2
Wearing the wrong type of contact lenses with an outdated prescription or incorrect fitting can lead to blurry vision, discomfort, and an increased risk of eye damage and infections.7
How do toric lenses differ from other contact lenses?
Regular spherical contacts have one power across the entire lens and are effective even if they rotate with blinking.
Toric contact lenses have different powers in the horizontal and vertical meridians. They must remain rotationally stable in the eye for effective vision correction. So, toric contact lenses have special design features to ensure that the lens sits on the eye correctly and has minimal movement, to ensure sharp vision. They also have specific features, such as a weighted bottom, to prevent them from rotating.2
Expert fitting is required for toric contact lenses. A trial of more than one design and brand may be needed to find the lenses with the best comfort and visual acuity.2
Can you wear gas-permeable contact lenses for astigmatism?
Yes, rigid gas-permeable (RGP or GP) contact lenses can be used to correct astigmatism. Unlike soft contacts, RGP contact lenses for astigmatism do not always require a special toric design. This is because the rigid material retains its shape when applied to the eye (unlike soft lenses that conform to the irregular shape of the cornea).
RGP contact lenses compensate for the misshapen cornea and provide a uniform surface for light to pass through. As a result, they can sometimes correct astigmatism without the need for a special toric design.2
Many people with astigmatism find that RGP lenses provide noticeably sharper vision than soft contact lenses for astigmatism. However, because of the rigid material and thicker lens, it can take several weeks of adjustment to become accustomed to the RGP lens on the eye.
RGP contact lenses for astigmatism are custom-made and, therefore, cost more than soft toric contact lenses. Replacement lenses are also more expensive. Fitting requires more expertise and time than soft contact lenses for astigmatism.2
Can aspheric contact lenses help astigmatism?
In an aspheric contact, the power changes gradually from the centre to the edge of the lens. This is believed to minimise aberrations and improve depth perception and contrast sensitivity.3 Optometrists will sometimes prescribe aspheric contact lenses to people with low levels of astigmatism. However, the effectiveness of an aspheric contact lens depends on several factors, such as:
- Pupil size
- Ocular shape
- Refractive error
Each of these varies from person to person. Therefore, an average design may not improve vision for the majority of wearers. Aspheric contact lenses may help astigmatism in some individuals with large pupils and high refractive errors, particularly hyperopia (far-sightedness).4
Multifocal toric contact lenses for astigmatism
Astigmatism is a very common condition that can occur at any age. Presbyopia is also very common and usually occurs at age 40 to 45 when objects up close (such as a menu card or book) appear blurred. Varifocal (multifocal) toric contact lenses address both problems — astigmatism and presbyopia.2 Trusted brands have developed varifocal toric lenses with advanced optical technologies that permit same-day fitting.7
Book an appointment
To find out more information regarding astigmatism and contact lenses, book an appointment to chat with one of our friendly Specsavers optometrists, or you can browse our full range of toric contact lenses here.
If you are interested in discovering more about wearing contact lenses with other eye conditions, you can learn more in our dedicated resource.
- Handley, N. (no date). Disposable lenses. [Online] College-optometrists.org. Available at: https://www.college-optometris... [Accessed 2 November 2019].
- Fahmy M, Long B, Giles T, Wang CH. Comfort-enhanced daily disposable contact lens reduces symptoms among weekly/monthly wear patients. Eye Contact Lens. 2010 Jul;36(4):215-9. Available at: https://www.ncbi.nlm.nih.gov/p... [Accessed 2 November 2019].
- Dumbleton KA, Woods CA, Jones LW, Fonn D. Comfort and adaptation to silicone hydrogel lenses for daily wear. Eye Contact Lens. 2008 Jul;34(4):215-23. Available at: https://www.ncbi.nlm.nih.gov/p... [Accessed 2 November 2019].
- American Optometric Association. (no date). Treating Dry Eye Symptoms in Contact Lens Patients. [Online]. Available at: https://www.aoa.org/Documents/... [Accessed 2 November 2019].
- Markoulli M, Kolanu S. Contact lens wear and dry eyes: challenges and solutions. Clin Optom (Auckl). 2017;9:41–48. Published 2017 Feb 15. Available at: https://www.ncbi.nlm.nih.gov/p... [Accessed 2 November 2019].
- Nichols JJ, Lievens CW, Bloomenstein MR, Liu H, Simmons P, Vehige J. Dual-Polymer Drops, Contact Lens Comfort, and Lid Wiper Epitheliopathy. Optom Vis Sci. 2016;93(8):979–986. Available at: https://www.ncbi.nlm.nih.gov/p... [Accessed 2 November 2019].
- Livestrong. (no date). The Effects of Wearing Wrong Prescription Contacts. [Online]. Available at: https://www.livestrong.com/article/193947-the-effects-of-wearing-wrong-prescription-contacts/ [Accessed 27 September 2019].