Astigmatism is a condition that causes blurred vision when the lens or cornea of an eye has an irregular surface contour, according to Mayo Clinic. Rather than having a consistently smooth curvature, an astigmatic lens or cornea has abnormal curves and flattened areas, changing how the eye processes light.Know More
As light passes into the eye, the cornea and lens work together to focus incoming rays toward the retina and produce a clear image, explains the American Optometric Association. Shape irregularities can change how different sections of the cornea or lens surface refract light, distorting the eye's focal point. For example, the corneal surface may be oval-shaped instead of spherical. If the condition is not present at birth, it may develop after a surgery or injury.
Astigmatism is known as a refractive error, and physicians usually classify it as corneal or lenticular, notes Mayo Clinic. Blurriness caused by refractive distortion occurs in the same direction as the abnormal curvature, such as vertically, horizontally or diagonally. In addition to vision problems, people with astigmatism may develop headaches or eye strain.
Serious cases are often accompanied by myopia, known as nearsightedness, or hyperopia, known as farsightedness, according to Mayo Clinic. In a nearsighted eye, an excessively curved cornea shortens the point of focus, making far off objects seem blurry. In farsighted vision, a cornea lacking curvature or an unusually short eye makes the point of focus longer than normal, so closer objects appear blurry.Learn more in Vision
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According to the Eye Care Office of Ofner, Neale and Fleming, cataracts of the eye create a clouding of the lens inside the eye, behind the pupil or iris (the colored portion of the eye), that is often mistaken for a film over the eye. Cataracts are a common aspect to the aging process. Early signs of cataracts include decreased distance vision and decreased vision while reading.Full Answer >
An image is formed in the human eye when light passes through the pupil, is refracted by the lens and is absorbed by pigment cells in the retina, altering the pigments and triggering neurons to fire. The particular arrangement of the stimulated cells is interpreted by the brain into a separate image for each eye. The two eyes look at images from slightly different angles, allowing the perception of depth.Full Answer >
People should get their eyes checked because the early signs of some eye diseases are silent or vague, according to the Centers for Disease Control and Prevention. Also, a child may be too young to know that her vision is not as sharp as possible and may need corrective lenses.Full Answer >