What Is the Axis of the Eye?

The human eye is made of many smaller parts that coordinate to create vision. Important to proper reception of visual material are the two axes of the eye. These axes are not actual structures; rather they are imaginary lines drawn between points.

Optical Axis

• The optical axis of the eye is an imaginary line that spans from the centers of the curvature of the front and back surfaces of the lens. This straight line creates an imaginary division between the left and right sides of the eye.

Visual Axis

• The visual axis of the eye is an imaginary straight line that extends from the object being viewed, through the pupil, and to the center of the fovea. Located at the back of the eye, the fovea is responsible for sharp central vision that provides detail to sight. The orbital muscles keep the visual axis of both eyes at the center of the object that is being viewed.

Disorders

• Strabismus, or cross-eye, may occur when the orbital muscles of the eye are damaged.

  Damage to the visual or optical axes of the eye will result in poor vision. Strabismus occurs when the orbital muscles of the eye are unable to coordinate the visual axis between both eye. In this condition, more commonly known as cross-eye, the eyes are unable to align themselves either constantly or intermittently.