Contact lens for Astigmatism

  • 2019-05-06
  • sam

Astigmatism, an often misunderstood term is more like any other refractive error problem. Yes! A simple problem in how the eye focuses light Before we delve deeper, let’s get a basic idea of how an eye generates vision. Very simply, when you see an object, the light emitted from it falls on the eye. The eye then focuses this light on the retina and generates the image of what you see and even how you see it. Understanding Astigmatism

What is astigmatism? Well, when the eye is unable to focus the light on the retina and manages to do so in front of it or even behind it, the person is likely to be suffering from some degree of astigmatism. Just like nearsightedness and farsightedness, the solution for astigmatism also lies in opting for the right lens. Primarily there are three types of astigmatism. First is myopic astigmatism where one or both principal meridians of the eye are nearsighted, basically myopic in differing degree. Second is the hyperopic astigmatism where one or both principal meridians of the eye are farsighted and the third type is mixed astigmatism where you see symptoms of both nearsightedness and farsightedness. Many lens makers specialise in offering lens for astigmatism and we will tell you more about them a little later in this article. Another offshoot of this variation is irregular astigmatism which is often a result of some accident or injury, involving the eye. Symptoms and detection Those suffering from astigmatism are likely to experience blurred or distorted vision. Astigmatism is of two types – regular and irregular. The regular one is more like a refractive error arising from the eye’s inability to focus light while the irregular is more often a result of injury or damage to the eye. Since astigmatism usually occurs early in life, a regular eye exam is the best way to detect it. Ideally, it is always advised to check if your customer has sought medical diagnosis before approaching you for an astigmatism lens. Correcting astigmatism Astigmatism usually can be corrected with eyeglasses, contact lenses or refractive surgery. Now let’s move towards the lens correction options for those who suffer from astigmatism. Usually, a spherical lens is used to correct nearsightedness or farsightedness. For astigmatism, an additional “cylinder” lens power is added to the above options. This cylindrical lens power is used to correct the difference between the powers of the two principal meridians of the eye. The cylindrical lens power is what the optician will likely see as a cylindrical axis in the ophthalmologist’s prescription.

Option for lens wearers Soft toric contact lenses are also used for astigmatism correction, just that the lens prescription will include a sphere power, cylinder power and axis designation. Gas permeable contact lenses are also an option as they can optically replace the cornea as the refracting surface of the eye. However, these lenses are rigid and therefore avoided. There are cases when a cylinder power and axis may not be needed. It all depends on the type and severity of astigmatism correction required. A similar theory can be applied for the hybrid contact lenses as well. Refractive surgery such as LASIK can also be used to correct astigmatism.

Soft toric contact lenses are also used for astigmatism correction, just that the lens prescription will include a sphere power, cylinder power and axis designation. Gas permeable contact lenses are also an option as they can optically replace the cornea as the refracting surface of the eye. However, these lenses are rigid and therefore avoided. There are cases when a cylinder power and axis may not be needed. It all depends on the type and severity of astigmatism correction required. A similar theory can be applied for the hybrid contact lenses as well. Refractive surgery such as LASIK can also be used to correct astigmatism.

Posted by sam
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