Despite its somewhat intimidating name, astigmatism is quite a common condition, and it can be successfully treated using corrective lenses or surgical intervention.
Astigmatism is an ocular condition involving the malformation of either the cornea or the lens. In moderate-to-severe cases, this condition inhibits light from entering the retina efficiently, causing vision to become blurred at any distance, and sometimes triggering headaches, poor night vision, and eye irritation. Most people are either born with, or will develop, a very mild degree of astigmatism; many cases do not result in any noticeable vision abnormalities.
What causes astigmatism?
The precise cause of astigmatism isn’t known, but it does correlate with other conditions. Many people are born with an inherited astigmatism. It has been known to develop as one ages, and is often seen before the onset of cataracts. Astigmatism may also be a reaction to eye surgery or an eye injury. A rare condition called keratoconus causes a type of astigmatism where the cornea begins to deteriorate slowly and becomes increasingly misshapen. Severe keratoconus-related astigmatism can be treated with a surgical replacement of the cornea once the condition has become advanced.
How is astigmatism diagnosed?
If you have blurred vision at any distance – meaning you can’t see objects clearly no matter how near or far they are – you may have astigmatism. However, it very often appears with either myopia (nearsightedness) or hyperopia (farsightedness), so the degree of severity may not be apparent without a comprehensive evaluation. Here is what your eye care specialists will check when evaluating for astigmatism:
- Visual acuity. Visual acuity is your ability to see symbols clearly at a specified distance. 20/20 vision is the ability to clearly read a letter or number from 20 feet that has been designated as being readable at a 20-foot distance.
- The curve of the cornea. The keratometer is a tool that uses light to measure corneal curvature and assess the degree of astigmatism severity. Your eye care specialist may also use a corneal topographer, which is a more sophisticated instrument that offers greater detail of the cornea, providing a three-dimensional map of the corneal surface.
- Refraction. This exam tests the focusing power of the eye using a device called the phoropter. It measures refractive error by placing a series of lenses before the patient, with the patient telling the optometrist which lenses produce the best correction.
What are astigmatism treatment options?
Depending upon the results of the examination, your optometrist may offer you the following correction solutions:
- Eyeglasses. Eyeglasses remain the most common corrective measure for people with astigmatism. These may be single focus, or in the case with people with presbyopia, progressive lenses that address multiple distance issues.
- Contact lenses. Contact lenses have an advantage over glasses because they can physically correct the shape of the cornea, provided they are gas permeable or rigid lenses. Soft contacts are not effective for astigmatism, because they adjust to the shape of the corneas instead of reshaping them.
- Orthokeratology/Ortho-k. This procedure is the fitting of retainer contact lenses for corrective wear. The lenses reshape the corneas over time, improving the wearer’s vision even when corrective lenses or eyeglasses are not worn. While ortho-k does provide prolonged correction, the technique does not permanently alter the corneas; the retainer lenses must be worn periodically to ensure long-term results.
- Surgical intervention/LASIK. LASIK (laser in situ keratomileusis) surgery is a process that reshapes the cornea by removing the inner tissue. This is a permanent solution, and it can fully correct moderate to severe astigmatism.
If you think you have any type of vision problem, including astigmatism, don’t hesitate to have a comprehensive eye evaluation performed.
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