What Is Astigmatism and How to Fix It
Astigmatism is most likely the most misinterpreted vision issue. For starters, it’s called “astigmatism,” not “stigmatism.” (You don’t have “a stigmatism” – you have astigmatism.)
Like nearsightedness and farsightedness, astigmatism is a refractive error, implying it is not an eye illness or eye illness; it’s merely a problem with how the eye focuses light.
What Is Astigmatism
In an eye with astigmatism, light fails to pertain to a single concentrate on the retina to produce clear vision. Rather, numerous focus points take place, either in front of the retina or behind it (or both).
Examples of Astigmatism | Watch video
Astigmatism typically triggers vision to be blurred or misshaped to some degree at all distances.
Signs of uncorrected astigmatism are eye stress and headaches, especially after checking out or other extended visual tasks.
Squinting also is a very common symptom.
What Causes Astigmatism?
Astigmatism usually is dued to an irregularly shaped cornea. Instead of the cornea having a symmetrically round shape (like a baseball), it is shaped more like a football, with one meridian being substantially more rounded than the meridian perpendicular to it.
(To understand exactly what meridians are, think of the front of the eye like the face of a clock. A line linking the 12 and 6 is one meridian; a line linking the 3 and 9 is another.).
The steepest and flattest meridians of an eye with astigmatism are called the primary meridians.
Sometimes, astigmatism is dued to the shape of the lens inside the eye. This is called lenticular astigmatism, to separate it from the more common corneal astigmatism.
Three Types of Astigmatism
There are 3 main kinds of astigmatism:
- Myopic astigmatism. One or both primary meridians of the eye are myopic. (If both meridians are nearsighted, they are myopic in differing degree.).
- Hyperopic astigmatism. One or both principal meridians are farsighted. (If both are farsighted, they are hyperopic in differing degree.).
- Mixed astigmatism. One prinicipal meridian is myopic, and the other is farsighted.
Astigmatism also is classified as regular or irregular. In routine astigmatism, the principal meridians are 90 degrees apart (perpendicular to each other). In irregular astigmatism, the principal meridians are not perpendicular. A lot of astigmatism is regular corneal astigmatism, which gives the front surface area of the eye a football shape.
Irregular astigmatism can arise from an eye injury that has triggered scarring on the cornea, from specific kinds of eye surgery or from keratoconus, a condition that triggers a gradual thinning of the cornea.
How Common Is Astigmatism?
Astigmatism typically occurs early in life, so it is necessary to arrange an eye exam for your kid to avoid vision issues in school from uncorrected astigmatism.
Signs of astigmatism consist of eye strain and headaches, specifically after checking out.
In another study of more than 11,000 eyeglass wearers in the UK (both children and adults), 47.4 percent had astigmatism of 0.75 D or higher in at least one eye, and 24.1 percent had this amount of astigmatism in both eyes. The prevalence of myopic astigmatism (31.7 percent) was roughly double that of hyperopic astigmatism (15.7 percent).
In a current research of 2,523 American youngsters ages 5 to 17 years, more than 28 percent had astigmatism of 1.0 diopter (D) or greater.
Also, there were considerable differences in astigmatism prevalence based upon ethnicity. Asian and Hispanic youngsters had the greatest prevalences (33.6 and 36.9 percent, respectively), followed by whites (26.4 percent) and African-Americans (20.0 percent).
Astigmatism is found throughout a routine eye examination with the same instruments and techniques used for the detection of nearsightedness and farsightedness.
Your optometrist can estimate the amount of astigmatism you have by shining a light into your eye while by hand introducing a series of lenses in between the light and your eye. This test is called retinoscopy.
Though many optometrist remain to carry out retinoscopy, this manual treatment has been replaced or supplemented in lots of eye care practices with automated instruments that offer a much faster initial test for astigmatism and other refractive errors.
Whether your eye exam consists of retinoscopy, an automated refraction, or both, your optometrist or eye doctor will carry out another test called a manual refraction to fine-tune the results of these preliminary astigmatism tests.
In a manual refraction (likewise called a manifest refraction or subjective refraction), your eye doctor places an instrument called a phoropter in front of your eyes. The phoropter consists of numerous lenses that can be introduced in front of your eyes one at a time so you can compare them.
As you look through the phoropter at an eye chart at the end of the examination room, your eye doctor will show you different lenses and ask you questions along the lines of, “Which of these 2 lenses makes the letters on the chart look clearer, lens A or lens B?” Your answers to these questions help identify your spectacles prescription.
Astigmatism Correction Options
Astigmatism, like nearsightedness and farsightedness, typically can be corrected with eyeglasses, contact lenses or refractive surgery.
In addition to the spherical lens power utilized to fix nearsightedness or farsightedness, astigmatism requires an extra “cylinder” lens power to correct the difference in between the powers of the two primary meridians of the eye.
So a glasses prescribed for the correction of myopic astigmatism, for instance, could resemble this: -2.50 -1.00 x 90.
- The first number (-2.50) is the sphere power (in diopters) for the correction of myopia in the flatter (less myopic) principal meridian of the eye.
- The second number (-1.00) is the cylinder power for the added myopia correction required for the more curved principal meridian. In this case, the total correction needed for this meridian is -3.50 D (-2.50 + -1.00 = -3.50 D).
- The 3rd number (90) is called the axis of astigmatism. This is the place (in degrees) of the flatter principal meridian, on a 180-degree rotary scale where 90 degrees designates the vertical meridian of the eye, and 180 degrees designates the horizontal meridian.
If you wear soft toric contact lenses for astigmatism correction, your contact lens prescribed will similarly consist of a sphere power, cylinder power and axis classification.
Gas permeable contact lenses are likewise an alternative. Because these lenses are rigid and optically replace the cornea as the refracting surface area of the eye, a cylinder power and axis may or may not be required, depending on the type and extent of astigmatism correction required. The very same is true for hybrid contact lenses.
Refractive surgery such as LASIK also can remedy most kinds of astigmatism. Talk about with your optometrist which procedure is very well for you.
Lasik laser eye surgery video explained and narrated
Can laser eye surgery fix astigmatism?
Yes, in most cases, LASIK laser eye surgery can totally correct astigmatism, and the impact is long-term.
Astigmatism is a very common vision problem. Despite having a somewhat scary-sounding name, astigmatism is not an eye disease – it’s merely a refractive error like nearsightedness and farsightedness – and it can be fixed with glasses, contact lenses and LASIK surgery.
Astigmatism typically is caused by the front surface area of the eye (cornea) having an asymmetrical shape.
An example that’s commonly used to describe this is to state the cornea is shaped like a football rather than like a baseball. Another is to state that an eye with astigmatism is formed like an egg or the back of a spoon, instead of like a ping-pong ball.
The ultra-precise lasers made use of for LASIK surgery can be configured to improve the cornea so the front surface area of the eye is more symmetrical, therefore getting rid of vision problems caused by astigmatism.
When astigmatism is present, it usually does not surpass 3.0 diopters (D) in magnitude and can be fully fixed with a single LASIK procedure.
Even greater quantities of astigmatism laser eye surgery can fix astigmatism, though this enhances the possibility a follow-up LASIK improvement may be had to tweak the correction.
If you have high astigmatism, this may impact your LASIK surgery cost, depending upon the policies of the LASIK surgeon and/or surgery center you choose. If so, this will be gone over with you throughout your preoperative examination and assessment.
Last modified: August 6, 2016