A duction is an eye movement involving only one eye

Human eye

The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...

. There are generally six possible movements depending upon the eye's axis of rotation:

1. Abduction refers to the outward movement of an eye.
2. Adduction
   Adduction
   Adduction is a movement which brings a part of the anatomy closer to the middle sagittal plane of the body. It is opposed to abduction.-Upper limb:* of arm at shoulder ** Subscapularis** Teres major** Pectoralis major** Infraspinatus...
   
   refers to the inward movement of an eye
3. Supraduction / circumduction / elevation
4. Infraduction / deorsumduction / depression
5. Incycloduction / intorsion
6. Excycloduction / extorsion

Forced duction test

The forced duction test is performed in order to determine whether the absence of movement of the eye is due to a neurological disorder or a mechanical restriction.

The anesthetized conjunctiva is grasped with forceps and an attempt is made to move the eye ball in the direction where the movement is restricted. If a mechanical restriction is present, it will not be possible to induce a passive movement of the eye ball