Common Eye Problems

Chinese Version

Human Eye Structure

• Myopia

A condition of the eye where the light that comes in does not directly focus on the retina but in front of it, causing the image that one sees when looking at a distant object to be out of focus. It does not affect focus when looking at a close object.

• Hyperopia/ hypermetropia

A defect of vision caused by an imperfection in the eye, causing the eye to not have enough power to see in the distance. Correction is usually achieved by the use of convex corrective lenses. For near objects, the eye has to accommodate even more. Depending on the amount of hyperopia and the age of the person which directly relates to the eye's accommodative ability, the symptoms can be different.

(Upper: Hypermetropic, Middle: Emmetropic, Lower: Myopic)

• Astigmatism

Astigmatism is an optical defect in which vision is blurred due to the inability of the optics of the eye to focus a point object into a sharp focused image on the retina. This may be due to an irregular or toric curvature of the cornea or lens.

• Presbyopia

Presbyopia is a condition associated with aging in which the eye exhibits a progressively diminished ability to focus on near objects. Presbyopia’s exact mechanisms are not fully understood; research evidence most strongly supports a loss of elasticity of the crystalline lens, although changes in the lens’s curvature from continual growth and loss of power of the ciliary muscles (the muscles that bend and straighten the lens) have also been postulated as its cause.

*The information above are from Wikipedia.