Astigmatism, like myopia, hyperopia, and presbyopia, is a refractive error that impairs vision. Astigmatism is a somewhat more complex refractive error to correct, though modern technology has produced contact lenses that have proven themselves to be an effective and comfortable method of correcting astigmatism.
Before we can really understand how astigmatism influences sight, we need to first understand what a refractive error is.
What is a “Refractive Error”?
A refractive error is a physical abnormality in the size, shape, or curvature of the eye. Due to this abnormality, light that enters the eye is incorrectly refracted, resulting in impaired vision.
Refractive errors can occur at different levels of severity and impairment. Some people will have a minor prescription, while others will require significant correction.
Understanding Refraction
When light enters the eye, it passes through the cornea and lens where it is focused onto the retina. The cornea/lens refracts the incoming light directly onto the surface of the retina- this provides clear vision.
When a refractive error occurs, the light is not focused directly on the retina. This creates vision impairment associated with the respective refractive error.
What Causes Astigmatism?
A myopic eye is “too long” relative to the focusing power of its lens, and a hyperopic eye is “too short”. In the case of astigmatism, the refractive error is a result of the cornea or lens (or both) have irregular curvature. Essentially, the eye has multiple focusing powers which, when left uncorrected, results in an uneven refraction.
Symptoms
- Difficulty seeing objects (distant, near, or both)
- Eye strain
- Squinting to see
Treatments to Correct Astigmatism
Like other refractive errors, the most effective treatment for astigmatism is via corrective lenses. Laser refractive surgery is also an option for many people with astigmatism.
Corrective Lenses
Eyeglasses (sometimes called spectacles) and contact lenses are ideal methods of correcting astigmatism. Both types of lenses are able to be built with multiple focusing powers (necessary to correct astigmatism).
Laser Refractive Eye Surgery
Laser eye surgery is a long-term treatment for astigmatism. Where corrective lenses sit overtop of the eye and correct the refraction, laser eye surgery physically reshapes the idea.
The procedure is quite safe and effective. However, it does come with significant expenses compared to corrective lenses, and the risk of side-effects does exist.
