Amblyopia: reduced vision in one eye that otherwise appears to be normal. also called Lazy Eye

Anisometropia: Difference in refractive power (prescription) between the 2 eyes

Astigmatism: irregularities in the shape of the cornea resulting in difficulties focusing

Cataract: cloudiness of the lens

Ciliary Muscles: muscles in the eye that automatically contract or relax the shape of the lens of the eye so a clear image is projected onto the retina

Color Blind: Inability to distinguish certain colors

Conjunctivitis: infection of the outer layer of the eye, often referred to as "pink eye"

Contrast Sensitivity: the level of ability to see shading differences, often measured as a percentage

Cornea: the clear outermost layer of the eye

Depth Perception: the ability to see the world in 3-D, even though the image focused on the retina is flat.

Dilating: a process using special eyedrops to cause the pupil to enlarge, permitting the doctor to see inside the eye

Eye Coordination: the two eyes working together

Hyperopic: farsighted

Focusing: the act of the eye muscles changing the shape of the lens in order to form a clear image of the world on the retina

Fovea: the part of the retina that is specialized for good detail vision as well as for good color vision

Iris: the flat colored part of the eye. It has tiny muscles that enlarge and reduce the size of the pupil

Lazy Eye: amblyopia

Lens: the part of the eye that allows light and images to enter, thus forming images on the retina

Myopic: nearsighted

Nystagmus: a condition where the eyes involuntarily jump or wiggle around

Peripheral Vision: the visible area outside of the point of focus

Presbyopia: normal aging of lens and eye muscles, typically after age 40

Pupil: the opening of the eye in the center of the iris

Retina: the receiving surface at the back of the eye on which visual images are formed

Sclera: the protective outer layer of the eye; known as the white of the eye

Strabismus: condition where the eyes are not working together; one or both are turned in or turned out

Tracking: the ability to follow an object with the eye

Visual Acuity: good detail vision

Wandering Eye: a condition where an eye moves independent of the focused one, usually in an outward direction