Pristely Smith Perimeter
The perimeter is an instrument for accurate
charting of the field of vision. It consists of. A vertical stand on which a
metallic arc is pivoted. It also bear a circular black disc to read the
meridian in which the arc in shape of a semicircle with radius 330 mm. Its
rotating in any direction and fix at any position with a tightening screw. The
arc is graduated from 0° to 90° with a movable test object which is a white
color spot of size 10mm diameter painted on a circular disc it can be moved
with arc. An adjustable chin rest and a detachable leveling bar is fixed in
front of the metallic arc. A scale and circular chart frame to hold the chart
paper in position is provided at the back of the circular disc. A metallic
graduated scale with a movable pin-punch pointer is fixed to mark on the
perimeter chart paper