Myopia is a condition in which the visual images come to a focus in front of the retina of the eye resulting especially in defective vision of distant objects. Myopia is typically a result of the eyeball be slightly longer than normal.
Hyperopia is a condition of the eye in which vision is better for distant objects than for near objects; although this may also result in blurriness of distant object as well. It results from the eyeball being too short from front to back, resulting in images focusing behind the retina.
Presbyopia is the gradual loss of your eyes’ ability to focus between far and near objects. This natural part of aging usually becomes noticeable in the early to mid-40s and continues to worsen until around age 65.
Astigmatism is a refractive defect in which vision is blurred due to the inability of the cornea and lens of the eye to focus an object into a focused image on the retina. This may be due to an irregular or toric curvature of the cornea. Glasses or toric contact lenses can correct astigmatism arising from the cornea. A ‘toric’ surface resembles the surface of a football, rather than the spherical surface of a regular cornea. This optical shape gives rise to astigmatism in the eye.
Three options exist for the treatment of astigmatism, myopia or hyperopia: Refractive surgery, contact lenses and eyeglasses.