Defects in human eye and its parts?
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myopia ,hypermetropia,pressbyopia,astigmatism
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FOLLOWING ARE THE MOST COMMON TYPES OF EYE DEFECTS
MYOPIA or NEARSHIGHTED
Myopia occurs when the eyeball is too long, relative to the focusing power of the cornea and lens of the eye. This causes light rays to focus at a point in front of the retina, rather than directly on its surface If you're nearsighted, the first number ("sphere") on your eyeglasses prescription will be preceded by a minus sign (–). The higher the number, the more nearsighted you are.
HYPEROPIA or FARESIGHTED
This vision problem occurs when light rays entering the eye focus behind the retina, rather than directly on it. The eyeball of a farsighted person is shorter than normal
Farsightedness can be corrected with glasses to change the way light rays bend into the eyes. If your glasses begins with plus numbers, like +1.50, you are farsighted.
ASTIGMATISM
Instead of the cornea having a symmetrically round shape (like a tennis ball), it is shaped more like a rugby ball, with one meridian being significantly more curved than the meridian perpendicular to it
Astigmatism usually causes vision to be blurred or distorted to some degree at all distances. Symptoms of uncorrected astigmatism are eye strain and headaches, especially after reading or other prolonged visual tasks
Astigmatism is usually combined with Myopia or Hyperopia.
PRESBYOPIA
Presbyopia generally is believed to stem from a gradual thickening and loss of flexibility of the natural lens inside your eye
Presbyopia usually occurs beginning at around age 40, when people experience blurred near vision when reading, sewing or working at the computer. Everyone becomes presbyopic.
MYOPIA or NEARSHIGHTED
Myopia occurs when the eyeball is too long, relative to the focusing power of the cornea and lens of the eye. This causes light rays to focus at a point in front of the retina, rather than directly on its surface If you're nearsighted, the first number ("sphere") on your eyeglasses prescription will be preceded by a minus sign (–). The higher the number, the more nearsighted you are.
HYPEROPIA or FARESIGHTED
This vision problem occurs when light rays entering the eye focus behind the retina, rather than directly on it. The eyeball of a farsighted person is shorter than normal
Farsightedness can be corrected with glasses to change the way light rays bend into the eyes. If your glasses begins with plus numbers, like +1.50, you are farsighted.
ASTIGMATISM
Instead of the cornea having a symmetrically round shape (like a tennis ball), it is shaped more like a rugby ball, with one meridian being significantly more curved than the meridian perpendicular to it
Astigmatism usually causes vision to be blurred or distorted to some degree at all distances. Symptoms of uncorrected astigmatism are eye strain and headaches, especially after reading or other prolonged visual tasks
Astigmatism is usually combined with Myopia or Hyperopia.
PRESBYOPIA
Presbyopia generally is believed to stem from a gradual thickening and loss of flexibility of the natural lens inside your eye
Presbyopia usually occurs beginning at around age 40, when people experience blurred near vision when reading, sewing or working at the computer. Everyone becomes presbyopic.
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