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Eye Condition & Diopter

icon Myopia
 
Myopia   Myopia (also called short-sightedness)
is a condition in which the eyeball it self is either too long,
or the front of the eye (the cornea) is too curved, or a combination of both.
The result is that light from distant objects is focused in front of the retina
(instead of on the retina). This makes doing things like driving and reading
far-off signs difficult. Myopia can be corrected with either soft (disposable) contact lenses or RGP (gas permeable) contact lenses.
 
icon Hyperopia
 
Myopia   Hyperopia (also called hypermetropia or long-sightedness) is a
condition in which the eyeball is too short, or the cornea is too curved, or a combination of both. The result is that light from objects is focused behind the retina. We can use some of the focusing power of the natural lens
within the eye to help refocus the light, but this can lead to "eyestrain" or
tired eyes, especially when working at near. The focusing ability of the eyes also reduces as we get older, making it more difficult to overcome the
focusing problem. Hyperopia can be corrected with either soft (disposable) contact lenses or RGP (gas permeable) contact lenses.
 
icon Astigmatism
 
Astigmatism   Astigmatism is a condition in which the front of the eye (the cornea) is oval shaped instead of round. Some people describe it as having rugby ball
shaped cornea instead of a soccer ball shaped cornea.
There are two types of astigmatism, regular and irregular. Regular astigmatism is able to be corrected with glasses, soft (toric) and RGP (gas permeable) contact lenses.
The range of contact lenses available to correct regular astigmatism is
constantly increasing. Many people with astigmatism have been told in the past that their eyes aren't suitable for contact lenses, due to limited designs available at the time. You should consult your eye-care practitioner to find out if you may be able to be fitted now with the increased ranges of contact lenses.
Irregular astigmatism is usually not well corrected with spectacles or soft
 
contact lenses, unless it is fairly mild. It can be caused by conditions such as keratoconus and corneal scarring.
RGP (gas permeable) contact lenses correct the vision by maintaining their shape on the cornea, with any corneal irregularity being
filled by the tears behind the lens. Soft contact lenses, when tried with irregular astigmatism, tend to mould to the shape of the eye,
thus transferring the distortion.
 
icon What is diopter(D)
 
Describes the refractive (light bending) capability of a lens, it is proportional to the curvature of the lens.
The focal length (working distance) and diopter values of a lens are directly related. The diopter of a lens, can be established by viewing from a distance of 25 cm above the lens, then move the object to the greatest distance below the lens where it remains in sharp
focus. Divide this distance into 100 cm. The result is the diopter of the lens - e.g., if the object is at a 33 cm distance, then it is a 3-diopter lens (100/33 = 3D).

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