Position of gaze and axes

manishchaudhary

1. PHYSIOLOGY OF OCULAR MOTILITY Presented By: Manish Chaudhary B.Sc.Optometry ,3 rd year

2. INTRODUCTION To understand the occular movements and their mechanisms, a frame reference against which the movement may be quantified is necessary. There are mainly 3 position of eye i.e. Primary position secondary position Tertiary Position

3. PRIMARY POSITION Primary position of the eye is that position from which all other ocular movements are initiated changing the position of eyeball from primary to secondary or tertiary. The primary position has been described by the scobee as that of that position of the eyes in binocular vision when, with the head erect,the object of regard is at infinity.

4. SECONDARY POSITION These are the position assumed by the eyes , while looking straight up ( supraversion ), straight down( infraversion ),to the right( dextroversion ), and to the left( levoversion ).

5. TERTIARY POSITION These described the position assumed by the eyes,when combination of vertical and horizontal movements occur. These include position of the eyes in dextroelevation,dextrodepression,levoelevation,and levodepression .

6. POSITION OF GAZE All the extraoccular muscles have a given tone for every position of gaze. There are total 9 position of gaze,these include, 1 primary gaze,4 secondary gaze ,4 tertiary gaze.

7. CARDINAL POSITION OF GAZE These are the position which allow examination of each of the 12 extraoccular muscles of the two eyes,in their main field of action .

8. CENTER OF ROTATION It refers to a hypothetical point around which the eyeball performs rotatory movements. Earlier this has been assumed that the center of rotation is a fixed point. It has been reported that the center of rotation moves in a semicircle in the plane of rotation,this is called the space centroid.

9. AXES OF THE EXTRA OCCULAR MUSCLES Ficks described three axes to analyse all movement of the globe around the hypothetical centre of rotation. The proposed three axes are perpendicular to each other and intersect the center of rotation of the eye.

10. X-AXIS (HORIZONTAL) It lies horizontally ,when the head is in an upright position. Rotation around the horizontal axis result in elevation ( sursumduction )or depresssion ( deosursumduction ).

11. Y-AXIS (ANTEROPOSTERIOR) The anteroposterior axes of the two eyes are parallel to each other and perpendicular to the horizontal axis results in elevation or depression.

12. Z- AXIS (VERTICAL) It extends vertically when the head is in upright position and is perpendicular to the x and y axes. Rotation of globe around the vertical axes are known as adduction and abduction.

13. OBLIQUE AXIS The listing plane also contains two oblique axes o-o which allow the eyeball to rotate obliquely up and in and out ,down and down and out.

14. THANK YOU