A World Health Organization (WHO) report from 2019 found that 2.2 billion, about 30% of people worldwide suffer from visual impairment or sight loss, of which about half could have been prevented or were untreated . The report found that refractive error was the leading cause of visual impairment, and the second cause of sight loss worldwide. This article explores a common strategy called LASIK to treat a type of refractive error called astigmatism.
Refractive error and astigmatism
The report by WHO found that refractive error was the leading cause of visual impairment, and the second cause of sight loss.
Refractive error is when the shape of your eye prevents light from reaching the retina (light-sensitive tissue at the back of the eye) accurately, resulting in a blurred or distorted image. Types of refractive error are myopia (nearsightedness), hypermetropia (farsightedness), presbyopia and astigmatism.
Astigmatism occurs in two main forms: corneal astigmatism and lenticular astigmatism. When light enters the eye it is refracted (bent) first by the cornea (transparent layer protecting the eye) and then the lens (responsible for focusing mechanism of the eye), so that it is focused properly onto the retina. However, in eyes with astigmatism, the curvature of the lens and cornea are mismatched, resulting in inaccurate bending of light entering the eye.
In corneal astigmatism, the fault lies in the curvature of the cornea, and in lenticular astigmatism, it lies in the curvature of the lens. This inaccuracy means that people with astigmatism often have distorted or blurry vision. Astigmatism can be present from birth or can come as a result of eye disease or injury to the eye. Unlike myopia and hypermetropia, the visual distortion happens irrespective of whether the objects are far away or nearby. However, astigmatism can be present in the eye alongside myopia and hypermetropia.
Astigmatism treatment options
Astigmatism is most commonly treated using lenses such as spectacles or contact lenses and they can be adapted to specifically amend the imperfection in both corneal and lenticular astigmatism, however for some people glasses and contact lenses are not compatible with their lifestyle and preferences. Refractive surgery has become a popular alternative.
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Laser eye surgery is a type of refractive surgery, where corrections are made to an eye using a laser in order to correct their refractive error. There are many different types of laser eye surgery using different methods, of which one is LASIK (laser-assisted in situ keratomileusis) eye surgery.
In order to achieve vision correction for astigmatism through LASIK surgery, the eye surgeon will first ensure that you are a good candidate for the surgery and that you are not suffering from eye diseases that could interfere with the surgery results.
The eye surgeon might provide you with a mild sedative, as well as numbing eye drops, before using a laser to reshape the cornea. Laser is then used to remove small pieces of the cornea until vision correction is achieved. LASIK eye surgery is the most common form of laser eye surgery. It is recommended that you consult a doctor of ophthalmology when considering any laser surgery in order to understand if you are a good candidate for the procedure. It is normally recommended that patients should be over the age of 18 years old so that the majority of their eye growth has slowed.
Lasik surgery recovery and potential side effects
LASIK for astigmatism usually comes with minimal discomfort in the aftermath, and your vision recovery takes about 2 days. As with many surgical procedures, there are side effects that can come alongside the healing process after LASIK eye surgery.
A common side effect of laser eye surgery is increased dry eye symptoms. Dry eyes after laser eye surgery are caused by a reduction in tear production, and it is normal for these symptoms to persist for about 6 months after the surgery. Your eye doctor may prescribe eye drops to ease your symptoms. After LASIK surgery people may experience increased trouble seeing in low lighting, glare and haloes around light sources, but these symptoms normally resolve a few weeks after the surgery.
There are rarer side effects after astigmatism vision correction, for example under correction or overcorrection, as a result of not enough cornea being removed, or too much. To amend under correction you can undergo a second laser surgery called “an enhancement”, however, overcorrection is challenging to fix. Ironically, astigmatism can occur as a result of a LASIK procedure to correct astigmatism. This LASIK surgery-induced astigmatism can be the result of uneven tissue removal. These complications and side effects are less common, however, and are part of the reason that consulting the right eye doctor and surgeon is so important to proper laser-assisted vision correction.
 World Health Organization, “WHO launches first World report on vision,” Geneva, WHO, 2019.
 C. Wolfram, et al., “Prevalence of Refractive Errors in the European Adult Population: the Gutenberg Health Study (GHS),” Br J Ophthalmol. 2014.
 C. W. Pan et al., “Prevalence of Refractive Errors in a Multiethnic Asian Population: the Singapore Epidemiology of Eye Disease Study,” Invest Ophthalmol Vis Sci, vol. 54, pp. 2590-8, 2013.