Diseases
All the eye problems should be given proper attention and checked with the doctor immediately. The following is a list of common eye disorders/diseases and their possible causes.
Refractive error:

The most common vision disorders are refractive errors - specifically nearsightedness, farsightedness, and astigmatism. In each case, the eye does not refract the incoming light properly, so the image is blurred.
Cataract:

A "clouding" of the lens in your eye. As light passes through the cataractous lens, it gets diffused or scattered, resulting in blurred or defocused vision.
Glaucoma:

Optic nerve is damaged, leading to progressive, irreversible loss of vision. It is often, but not always, associated with increased pressure of the fluid in the eye.
Retinal detachment:

Disorder of the eye in which the retina peels away from its underlying layer of support tissue
Diabetic retinopathy:

It is a retinopathy (damage to the retina) caused by complications of diabetes mellitus, which can eventually lead to blindness.
Corneal ulcer:

A condition of the cornea that occurs when localized tissue has eroded usually causes a red, painful eye.
Strabismus (Squint):

A defect of vision in which one eye cannot focus with the other on an object because of imbalance of the eye muscles.
Amblyopia:

Commonly known as lazy eye, a condition in which a patient has decreased vision in one eye that leads to the use of the other eye as the dominant eye. A problem most commonly associated with children.
Low vision:

Condition in which a person is without a significant measure of vision but is not totally blind.
Dry Eyes:

When adequate tears are not produced, and /or unusual excessive evaporation of tears happens, this will cause eye irritation. This is called dry eye.