تعريف astigmatism في الإنجليزية الإنجليزية القاموس.
A defect of a lens such that light rays coming from a point do not meet at a focal point so that the image is blurred
A disorder of the vision, usually due to a misshapen cornea, such that light does not focus correctly on the retina causing a blurred image
Astigmatism is a refractive problem in which an eye doesn't focus light evenly A lens that has astigmatism isn't curved evenly in all directions In an eye that has astigmatism, usually the corneal curvature is greatest in one direction and least in the opposite direction This subtle difference in curvature tends to blur images that we see, so that the world looks stretched out (Cassel 20)
Astigmatism is blurry vision produced by football-shaped corneas which are too steep in one place and too flat in another Astigmatic corneas focus light in two different places in the eye, making both near and distance vision a problem
(optics) defect in an optical system in which light rays from a single point fail to converge in a single focal point (ophthalmology) impaired eyesight resulting usually from irregular conformation of the cornea
A refractive error caused by an uneven power of the cornea; light entering the eye comes to two points of focus rather than one; has an amount and an orientation
Astigmatism is a common type of distorted vision It appears as an unevenness in the "picture" which an eye receives, which occurs when the surface of the eye is not truly spherical A person can have astigmatism even without being nearsighted or farsighted It has various causes, and can be treated in a number of different ways, such as toric contact lenses or laser surgery
unequal curvature of the refractive surfaces of the eye as a result of which a ray of light is not sharply focused on the retina but is spread over a more or less diffuse area This results from the radius of curvature in one plane being longer or shorter than that of the radius at right angles to it
(ophthalmology) impaired eyesight resulting usually from irregular conformation of the cornea
A condition in which the surface of the cornea is not spherical, but is irregularly shaped like the back of a spoon An astigmatic cornea causes light images to focus on two separate points in the eye, creating a distorted image Symptoms range from visual discomfort in mild cases, to severe blurring, ghosting, and distortion similar to a reflection in a fun-house mirror The amount of astigmatism you have will appear in the second number of most glasses prescriptions The angle of direction (cylinder meridian or axis) of the astigmatism will be shown in degrees A prescription of -4 00 - 1 00 x 30°, would indicate that you have 1 00 diopter of astigmatism at 30 degrees axis
occurs when the cornea of the eye is somewhat spoon-shaped instead of round, causing two separate lines of focus, neither of which land on the retina of the eye The result is blurred and distorted vision at all distances
A refractive error usually caused by toric (like a rugby ball) curvature of the front surface of the eye Instead of being brought to a focus at one point at the back of the eye, light is focused in two lines at right angles to each other Astigmatism is easily corrected with glasses to bring the two lines to one point focus
A term used to describe the shape of the cornea With astigmatism the cornea is more curved in one direction like a football, instead of round like a basketball and often occurs with nearsightedness or farsightedness This causes light to focus on more than one point resulting in blurry and distorted vision
A condition where the cornea is irregularly shaped, causing distorted vision especially at near distances Either glasses or toric contact lenses can correct astigmatism for most people Small amounts of astigmatism may be correctable with regular oxygen permeable lenses
A warping of the curvature of the cornea so that light rays entering the eye do not meet in a single focal point, resulting in a distorted image
— An additional curvature on the surface of the cornea, or lens of the eye, that makes it difficult to focus Slight degrees can cause headaches, fatigue and poor schoolwork More serious degrees produce blurred vision at all distances (NEI) - A condition in which the surface of the cornea is not spherical; causes a blurred image to be received at the retina
A defect of the eye or of a lens, in consequence of which the rays derived from one point are not brought to a single focal point, thus causing imperfect images or indistinctness of vision
If someone has astigmatism, the front of their eye has a slightly irregular shape, so they cannot see properly. difficulty in seeing clearly that is caused by a change in the inner shape of the eye (A- + stigma ; because there is no point at which light focuses). Lack of symmetry in the curvature of the cornea or, rarely, the lens of the eye. The unequal curvatures spread light rays, preventing them from being sharply focused at a point on the retina, causing blurring of part of the image. The effect of astigmatism can also be produced by misalignment of the lens. Astigmatic vision is corrected by means of lenses (see contact lens, eyeglasses) that refract the light rays to the proper degree in the opposite direction of that produced by the defects in curvature
Instead of the front surface of the eye being round it is more oblong This prevents the light being focused in the right way and leads to blurring Astigmatism can be secondary to the shape of the cornea or the lens, and is usually correctable with spectacle or contact lenses
Astigmatism nearly usually refers to the shape of the front of the eye, the cornea (occasionally astigmatism exists in the lens of the eye) It happens when all the light rays do not hit the fovea at the back of the eye all at one time, so you experience a range of blurriness A spherical cornea has no astigmatism, a cornea shaped more like the bowl of a spoon distorts images, the light rays are being bent and focused at more than one spot creating a less than clear image, the image appears to have a haze surrounding it, or a "ghost image "
Irregular shape of the cornea causing light rays to scatter at different points of focus, blurring near and distant vision In most cases of astigmatism, the cornea is shaped like the surface of a football - more steeply curved in one meridian
A refractive error caused by an irregular shape of the cornea (much like a football) Astigmatism is measured in terms of diopters, cylinder meridian or axis Uncorrected astigmatism may produce ghosting or double images
A refractive abnormality where light is not focused to a point on the retina This is often caused by the cornea or front window of the eye being elliptical (shaped more like an egg) rather than spherical (shaped like an orange) Refractive correction includes a lens which has focusing power in one axis and no power in the opposite axis The amount of astigmatism you have will appear in the second number of most glasses prescriptions ie - 4 00 -1 00 x 30°, or -5 00 +1 00 x 120 In both of the above cases you would have 1 00 Diopter of astigmatism
A distortion in the vision caused by irregular shape of the eye or its components As for example a rugby ball shape
a distortion of the image on the retina caused by irregularities in the cornea or lens
A condition that occurs when the front surface of the eye, the cornea, is slightly irregular in shape This irregular shape prevents light from focusing properly on the back of the eye (the retina) As a result, vision may be blurred at all distances
Astigmatism is an uneven curvature of the cornea resulting in blurry vision An astigmatic patient may be more curved on one side of the cornea than the other Astigmatism can result in an inability to focus clearly at any distance, because light rays entering the eye are bent unequally by the cornea, preventing the formation of a sharp point of focus on the retina Astigmatism often occurs in conjunction with myopia or hyperopia
(optics) defect in an optical system in which light rays from a single point fail to converge in a single focal point
A condition that occurs when the front surface of the eye (the cornea) is slightly irregular in shape This irregular shape prevents light from focusing properly on the back of the eye (the retina) As a result, vision may be blurred at all distances