Lazy eye, or amblyopia, is the loss or lack of development of normal vision in one eye that is unrelated to any eye health problem and cannot be corrected with lenses. It can result from a failure to use both eyes together. Lazy eye is often associated with crossed eyes or a large difference in the degree of nearsightedness or farsightedness between the two eyes. It usually develops before age 6, and it does not affect side vision.

Astigmatism is a vision condition that causes blurred vision due either to the irregular shape of the cornea (the clear front cover of the eye) or sometimes the curvature of the lens inside the eye.

Blepharitis is an inflammation of the eyelids and eyelashes. It causes red, irritated, itchy eyelids and dandruff-like scales on eyelashes.

A cataract is a cloudy area in the normally clear lens of the eye. Depending upon its size and location, it can interfere with normal vision. Most cataracts develop in people over age 55, but they occasionally occur in infants and young children. Usually cataracts develop in both eyes, but one may be worse than the other.

Conjunctivitis is an inflammation of the conjunctiva, the thin, transparent layer that lines the inner eyelid and covers the white part of the eye.

The three main types of conjunctivitis are infectious, allergic and chemical. The infectious type, commonly called "pink eye," is caused by a contagious virus or bacteria.

Diabetes is a disease that interferes with the body's ability to use and store sugar and can cause many health problems. Diabetic retinopathy occurs when small blood vessels in your eyes become damaged. These blood vessels nourish your eye's retina, the delicate, light-sensitive lining of the back of the eye.

The tears your eyes produce are necessary for overall eye health and clear vision. Dry eyes occur when the body can't produce enough tears or the specific components that make up tears.

Glaucoma is an eye disease in which the internal pressure in your eyes increases enough to damage your optic nerve and cause vision loss. The increased pressure occurs when the passages that allow fluid in your eyes to drain become clogged. The reasons the passages become blocked are not known.

Farsightedness, or hyperopia, is a vision condition in which distant objects are usually seen clearly, but close ones do not come into proper focus. Farsightedness occurs if your eyeball is too short or the cornea has too little curvature, so light entering your eye is not focused correctly.

Macular degeneration is the leading cause of blindness in America. It results from changes to the macula, a portion of the retina that is responsible for clear, sharp vision and is located at the back of the eye.

Nearsightedness, or myopia, is a vision condition in which near objects are seen clearly, but distant objects do not come into proper focus. Nearsightedness occurs if your eyeball is too long or the cornea has too much curvature, so the light entering your eye is not focused correctly.

Presbyopia is a vision condition in which the lens of your eye loses its flexibility, making it difficult to focus on close objects.

Spots (often called floaters) are small, semi-transparent or cloudy specks or particles in the fluid that fills the inside of your eyes. They appear as various-sized specks, threadlike strands or cobwebs. Because they are within your eyes, they move as your eyes move and seem to dart away when you try to look at them directly.

Strabismus occurs when one or both of your eyes turns in, out, up or down. Poor eye muscle control usually causes strabismus. This misalignment often first appears before a child reaches 21 months but may develop as late as age 6.