irregularity of the lens or cornea of the eye causing an image to be out of focus and producing faulty vision
Distorted spot resulting from imperfect focus caused by a defect of an optical system.
a visio n problem that results in blurred images. inocular vision - th e ability to use both eyes at once. ataract - a change in the structure of the crystalline lens that causes blurred vision.
The condition when an eye whose outer surface curvature is greater in one meridian than in another. The result is an eye that is shaped like a football instead of a basketball. With astigmatism, both distance and near vision are distorted. Vision can usually be corrected with glasses.
(uh-STIG-muh-tiz-um): A type of refractive error. Optical defect in which refractive power of an eye is not uniform in all directions (meridians). Large amount may result in headache and significant blurring of images.
Astigmatism is caused by an uneven or asymmetrical curvature of the cornea, which prevents the eye from focusing clearly at any distance. Astigmatism causes certain amounts of distortion or pitched images because of the uneven bending of the light rays entering the eye.
The lens' inability to bring radial and tangential lines into common focus on to the image circle.
Aberration that causes an image to not focus uniformly.
a disturbance of vision in which the refraction of the eye varies in different meridians
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.
A common disorder in which one or more of the eye's refractive surfaces (i.e., cornea, lens) is not symmetrical. Astigmatism causes a perceived image to become distorted or blurred.
A defect in optics in which a lens or mirror has two different amounts of curvature at 90 degrees to each other.
a defect of an ocular structure (most commonly the cornea or the crystalline lens) causing rays from a point to fail to meet in a single focal point, resulting in an imperfect blurred or smeared image; a defect of vision due to astigmatism of the refractive system of the eye
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.
The refractive error of the eye whose corneal surface curvature is out of round and shaped like a football such that both distance and near visions objects appear blurred and distorted.
Irregularity in curvature of the cornea or lens with consequential blurring and distortion of the image on the retina. Corrected by appropriate cylindrical external lens.
Abnormal condition of the eye in which the spherical curve of the cornea is irregular, causing blurred vision; may be corrected with contact lenses or eyeglasses.
Uneven curvature of the cornea in which refractive light rays are bent out of focus resulting in distorted vision. Those people with astigmatism are usually born with the disorder and it does not worsen with age. Often occurs in conjunction with nearsightedness or farsightedness. See General Eye Care in Free Eye Tests. See Cornea in Basic Anatomy.
A vision problem caused by unequal curvature of one or more surfaces of the eye, usually the cornea, which results in blurred vision.
is a distortion of the image on the retina usually caused by irregularities in the cornea.
A condition in which light rays are focused unevenly on the eye, which causes a distorted image due to an abnormal curvature of the cornea.
A condition that occurs when the cornea is misshapen to some degree, causing light to focus improperly on the retina.
Refractive error due to non-uniform meridians of curvature in the cornea preventing light rays from coming to a point focus. F G I J K L NO PQ RS TU VWXYZ Acronyms
Refractive condition wherein light rays entering the eye do not focus at a single point, resulting in blurred or distorted vision. Corrected by cylinder lenses.
A condition where the assymetrical shape (like a rugby ball) of the eye (cornea) results in two points of focus.
A defect of vision in which the image of an object is distorted, usually due to a football-shaped curvature of the cornea.
With astigmatism, the cornea (front surface of the eye) is shaped more like a football than a sphere, creating a distorted image on the retina.
(ophthalmology) impaired eyesight resulting usually from irregular conformation of the cornea
(optics) defect in an optical system in which light rays from a single point fail to converge in a single focal point
an abnormal curve in the optical part of the eye that produces a blurred image
an eye problem that results from a the lens or cornea being misshaped in a
an optical error of the eye and may cause some blurred vision particularly with lines and other objects in certain orientations or in certain angles
a refractive error in which the cornea is not perfectly spherical, like a basketball, but rather shaped more like a football
an aberration, or flaw, in a mirror or lens that causes the image of a point to blur into a line
Defect of vision in which the image of an object is distorted. The refraction of a ray of light is spread over a diffuse area rather than being sharply focused on the retina because of abnormal curving of the cornea and lens of the eye.
A defect in a lens that prevents sharp focusing. back to the
This one got me confused for a long time. It means that objects along a certain axis are always blurred, regardless of the viewing distance. Weird huh? Caused by a warping of the cornea, resulting in distortion along that axis.
A refractive error caused by the eye being an irregular shape. With astigmatism, the eye ball is shaped more like a football instead of a soccer ball. This type of refractive error is measured in diopters and cyclinder axis. Closed Loop Tracking – A system of tracking eye movement by sampling eye position thousands of times per second. In the case of laser vision correction, closed loop tracking provides continuous feedback to the laser about the position of the eye, and where the eye will be at the time the laser beam makes contact with the eye. The laser can then adjust the beam to compensate and ensure the laser is falling in the correct area. Logically this leads to improved accuracy.
An optical aberration resulting from unequal magnification across different diameters.
An asymmetric optical defect, characterized by figure differences on two or more axes. Picture a saddle or a Pringles(tm) potato chip -- examples of severe astigmatism.
This condition occurs when the cornea is not perfectly spherical and has an irregularity. The visual image is distorted so the parts are more in focus in one plane than in another; it is correctable with glasses. Astigmatism is often combined with myopia or hyperopia.
Vision condition which occurs when the cornea (front surface of the eye) has a slightly irregular shape. The irregularity prevents light from focusing properly on the retina (the back of the eye). Symptoms include blurred or distorted vision, headaches, eye strain and fatigue.
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 condition in which the surface of the cornea is elliptical rather than spherical. Causes a blurred image to be received at the retina. Refractive correction includes a lens that has focusing power in one axis and no power in the opposite axis. Astigmatism is often expressed in the second number of lens prescriptions and is measured in diopters.
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.
A condition where the eye is irregularly shaped, causing distorted vision. Toric contact lenses are used to correct for astigmatism.
A condition where the cornea is irregularly shaped, causing distorted vision especially at near dist ances. Either glasses or toric contact lenses can correct astigmatism for most people. Small amounts of astigmatism may be correctable with regular GP contacts.
Means that your cornea is shaped more like a football than a baseball - longer and flatter than round. If you have astigmatism, all objects are distorted, like looking through wavy glass. Until recently, astigmatism restricted you to glasses. Now there are even contact lenses that actually help correct the astigmatism, called toric contacts.
A condition in which the cornea is "out of round". The surface is not spherical like the surface of a standard ball but more angular like the surface of a football.
Condition where vision is distorted because the front of the eye is not totally spherical ie. it is shaped more like a rugby ball than a soccer ball. Clear vision is restored by an appropriate lens.
is a condition marked by an irregularity in the curvature of the cornea. The cornea is responsible for most of the focusing of light entering the eyes. Normally the cornea has a curvature similar to that of a basketball; with astigmatism, the corneal curvature more closely resembles that of a spoon or football.
results from an irregularly-shaped or football-shaped cornea which causes light to refract ineffectively. Vision irregularities depend on the exact nature of the astigmatism.
An optical defect which can exist alone or in combination with nearsightedness or farsightedness. In this condition, the cornea is oval or football-shaped instead of round or beachball-shaped; this causes distortion of the image.
A condition when the Cornea, (sometimes the lens) curves differently in different directions (a slice through a football). This causes objects (light) to bend differently to focus on the retina. The image is thus blurred, ghosted, or blurred unless corrected by contact lenses or spectacles.
An irregularity that causes distortion in the optics of the eye.
An error of refraction in which light rays are not focussed sharply on the retina. Astigmatism is due to differences in curvature of the cornea. Astigmatism is believed to be inherited, and can be improved or eliminated by corrective lenses or reshaping of the curvature with the Excimer laser.
Visual defect caused by abnormal curvature of the cornea that results in a blurry image.
A distortion in the vision caused by irregular shape of the eye or its components. As for example a rugby ball shape.
defocus of image caused by irregular corneal refracting power
When a cornea is perfectly spherical, no astigmatism exists. Yet, often the cornea is not quite spherical, but shaped more like a football rather than a basketball. Due to this shape, light that passes through the cornea focuses in more than one point, causing images to distort.
A refractive condition where the surface of the cornea is not spherical. A distorted image is formed because light images focus on 2 separate points in the eye.
A condition caused by irregularities in the eye. I causes images to become distorted or misshapen.
A common condition which can be repaired during a lasik procedure or with toric lenses. This condition is characterized by distorted vision and difficulty wearing normal contact lenses. The eye ball is usually shaped like football and irregular in size.
unevenness in the focusing of the eye
A common form of refractive error, caused when the cornea is not round but rather shaped like a football. The light rays entering the cornea focus on different planes, creating blurring and distortion.
irregular curvature of the cornea or lens resulting in a distorted image because light rays are not focused on a single point on the retina
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
a focusing distortion which is present at all distances, it can be cancelled out by a cylindrical component in an ophthalmic prescription (marked CYL on prescriptions). The angle of slant of the distortion is called its axis.
different degrees of refraction in the various meridians of the cornea
Causes light rays from an off-axis point to form images at different positions.
An optical aberration that causes the image of a point light source to appear as an ellipse.
A vision condition that occurs when the front surface of your eye, the cornea, is slightly irregular in shape. This irregular shape prevents light from focusing properly on the retina. Your vision may be blurred at all distances. People with astigmatism may experience headaches, eye strain, fatigue or blurred vision at certain distances. Most people have some degree of astigmatism.
Failure of an optical system, such as a lens or a mirror, to image a point source of light as a single point.
a vision problem that results in blurred images.
A defect of the lens resulting in blurred vision due to the fact that the lens does not focus light rays to a focal point.
The uneven foreground and background blur that is in an image.
a defect in an optical system in which rays from a point source fail to come to a point focus; usually due to an irregular optical surface such as the front surface of the cornea.
If the shape of the cornea is perfectly spherical there is no astigmatism. However, most corneas are not spherical but rather like the back side of a spoon. If you look at a spoon, you see that the shape across the spoon is more curved than the shape along the spoon. The greater the difference between the two curves the more astigmatism. The amount of astigmatism is measured during an eye examination. Astigmatism can be corrected with Laser Vision Correction techniques.
Light entering the eye focuses at two different points neither of which may be on the retina resulting in a blurred image. This is referred to as astigmatism. It is the result of the optical components of the eye - the cornea and the lens - having a non-spherical shape. Eyeglasses are required in many situations to accurately achieve focus on the retina.
refractive error which prevents light rays from coming to a point or focus on the retina, caused by unequal degrees of refractive power in the various meridians of the cornea
A condition in which refracted light is spread over a diffused area rather than sharply focused on the retina.
A visual defect in which the unequal curvature of one or more refractive surfaces of the eye, usually the cornea, prevents light rays from focussing clearly at one point on the retina, resulting in blurred vision.
A condition in which the light that enters the eye is brought to focus at different points within the eye. The object viewed will not be in focus without the proper correcting lenses. A non-spherical (not round) cornea usually causes this. The shape of the eye is often referred to as "egg shaped" rather than round.
an electron-optical lens aberration that causes the defocus to be a function of azimuth, and the contrast transfer function to deviate from circular symmetry about the optical axis. As a consequence, the Thon rings deform into elliptic or hyperbolic patterns, depending on the size of defocus and the size of the astigmatic defocus difference. See astigmatism as defined by SPIDER commands.
An aberration of a lens with spherical surfaces such that the image of a point not lying on the optical axis is a pair of short lines normal to each other and at slightly different distances from the lens. Radial and tangential lines are in focus in different image planes.
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 can be corrected with glasses, contact lenses, or refrative surgery. Go to Top
The condition in which the focal lengths of opposite meridians of an eye or optical system are not equal, thus producing two separate line images of a point source. Objects may appear to have a doubling or ghosting effect. Occurs when the eye is oval shaped instead of round. May exist alone or in combination with nearsightedness.
the refraction power of the eye is not the same in all meridians (eg.,more hyperopic vertically than horizontally).
An irregular curve, usually on the surface of the eye (cornea) or sometimes on the lens inside the eye, which prevents a sharp focus. May occur with or without near or far-sightedness.
Condition in which the cornea's curvature is asymmetrical (the eye is shaped like a football or egg instead of a baseball); light rays are focused at two points on the retina rather than one, resulting in blurred vision. Additional symptoms include distorted vision, eyestrain, shadows on letters, squinting and double vision. Read more about astigmatism.
condition of the eye in which the eye is shaped like a football instead of a baseball resulting of blurred vision
lens aberration making a single point light source impossible to focus as a true point.
A vision problem that results in blurred distance and/or near vision. Light rays entering the eye are bent unequally, which prevents the formation of a sharp point of focus on the retina. This creates a blurring of parts of objects you see.
A condition in which the surface of the cornea is not spherical, but bulges more in one axis than the other, 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 and poor focus. Corrective lenses have a non-rotationally symmetrical shape, either a convex or concave portion of a cylinder, orientated to counteract the eye's distortion. Contact lenses designed to correct for astigmatism are called Toric-lenses.
The condition in which light rays reaching the retina are distorted and one experiences difficulty seeing clearly at any distance without excessive focusing effort on their part.
A lens defect that prevents it from refracting light to form a sharp image.
(uh-STIG-muh-tizm) A condition in which the surface of the cornea is not spherical; causes a blurred image to be received at the retina.
An eye condition in which vision at all distances may be distorted due to irregularity in the shape of the front surface (cornea) of the eye.
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 problem with the eye that means when a person looks at an object it will appear distorted (blurred).
Uneven curvature of the cornea that causes light rays to focus in more than one place. This results in blurred images for both near and distance vision.
The distortion of an image resulting from a failure of light rays from different parts of the same zone to focus in the same plane.
Blurred vision caused by uneven curvature of lens or cornea.
Blurry vision caused by the abnormal curvature of the cornea.
A lens aberration in which a circle in the specimen appears as an ellipse in the image.
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 a football) rather than spherical (shaped more like a basketball). 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 i.e. -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.
Either the front of the eye, the cornea or the lenses has an irregular shape. It is more oval like a football, instead of spherical like a basketball. This causes incoming light to be focused on multiple points instead of just one
A condition of the eye that results in blurred distance and/or near vision. The surfaces of the eye focus the light rays at different points inside the eye. The different points of focus create a blur of parts of objects you see.
Condition caused by an irregularly shaped cornea, resulting in two focal points (blurred vision).
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.
an irregular or uneven corneal curvature that causes distortion or blurring of vision for objects at any distance.
Astigmatism is one of a group of eye conditions known as refractive errors. Refractive errors cause a disturbance in the way that light rays are focused within the eye. Astigmatism often occurs with nearsightedness and farsightedness, conditions also resulting from refractive errors. Astigmatism is not a disease nor does it mean that you have "bad eyes." It simply means that you have a variation or disturbance in the shape of your cornea. More...
lines in some directions are focused less sharply than lines in other directions
A condition in which blurred vision is caused by the cornea being shaped more like a football than spherical. Astigmatism may be compensated for through eyeglasses or contacts or can be corrected through refractive surgery.
A condition of asymmetric focusing, usually due to a malformation of the cornea.
a condition in which the surface of the cornea is not spherical; causes a blurred image to be received at the retina. Condition can be corrected with glasses.
(uh-STIG-muh-tiz-um). Refractive error. Optical defect in which refractive power is not uniform in all directions (meridians). Light rays entering the eye are bent unequally by different meridians, which prevents formation of a sharp image focus on the retina. Slight uncorrected astigmatism may not cause symptoms, but a large amount may result in significant blurring and headache.
Objects are blurred at all distances because the shape of the cornea is not uniform.
Blurred vision usually due to a congenital or acquired irregularity of the cornea. The image forms in back or in front of the retina, making near and far vision out of focus. Astimatism affects about 10% of the population.( astigmatisme, n.m)
Distorted vision due to corneal or lenticular irregularity or shape
An irregular curvature of the cornea. If it is shaped more like a football rather than a basketball, light is not sharply focused on the retina. This results in blurry vision for both distance and near. LASIK can help correct this disorder.
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.
Astigmatism is a condition caused by an irregularly-shaped cornea, which results in light images focusing on two separate points in the eye, creating a distorted image.
A condition of the eye that results in blurred vision. The cornea and lens focus the light rays at different points in front of or behind the retina. The different points of focus create a blur.
Occurs when the front surface of the eye or its internal lens is elliptical (rugby ball shaped) instead of spherical (football shaped). It can be associated with long ( hypermetropia) or short sightedness ( myopia).
A visual disturbance due to an irregularity in the shape of the cornea.
A common form of visual impairment in which part of an image is blurred, due to an irregularity in the curvature of the front surface of the eye, the cornea.
a refractive anomaly caused by unequal refraction of light in different meridians, resulting in a distorted and blurred image.
Uneven curvature of the cornea. Corrected with cylindrical lenses (denoted by plus or minus power and axis). Go to top of page
Refractive error in which light rays focus at different places inside the eye.
a distortion of the image on the retina caused by irregularities in the cornea or lens.
results if the cornea or lens of the eye is not shaped perfectly spherical (shaped more like a football than a basketball). The result is light being focused in several different planes.
a disorder in which the front surface of the eye (the cornea) is not correctly spherical, resulting in blurry vision
unequal corneal curvature. Vision is blurred and eye use causes discomfort. Accomadation does not correct the problem.
An irregularity in the curvature of the lens of the eye, resulting in a blurry or distorted image.
A refractive problem that occurs when the surface of the cornea is uneven or structurally defective, preventing the light rays from converging at a point.
In optics, astigmatism is when an optical system has different foci for rays that propagate in two perpendicular planes. If an optical system with astigmatism is used to form an image of a cross, the vertical and horizontal lines will be in sharp focus at two different distances.
Astigmatism is an affliction of the eye, where vision is blurred by an irregularly shaped cornea. The cornea, instead of being shaped like a sphere, is more oval-like and reduces the cornea's ability to focus light. Astigmatism is a refractive error of the eye in which there is a difference in degree of refraction in different meridians.