stereopsis and types of stereopsis tests

1. by :
stereopsis and types of
D.S.PREM SAGAR
13IMMO05, 3rd sem
stereopsis tests

2. stereopsis:
• stereopsis is the ability to perceive depth and 3- d structure
obtained on the basis of visual information deriving from two
eyes by individual with normally developed binocular vision
• stereopsis is usually reserved for the impression of depth arising
from binocular disparity
• stereopsis is measured at near as part of clinical assessment of
patients disorders of ocular motility and strabismus
• stereopsis can be measured near and distance

3. • contour stereopsis :
• The patient uses 3-D glasses and asked to look at a picture
and determine whether the 3-D figure can be seen
• the amount of disparity in images vary such as 400-100 sec
of arc and 800-40 sec of arc
• random dot stereopsis :
• The ran dot stereotest is a vectorgraph random dot
stereotest .It is frequently used for detecting amblyopia
,strabismus
• random dot test can measure stereoacuity to 20 seconds
of arc

4. • stereopsis is measured in seconds of arc (1* =60 minutes of arc ;
• 1 minute = 60seconds of arc )
• lower the value the better the acuity
• there are two types of stereopsis they are :
• 1.contour stereopsis
2.random dot stereopsis

5. Types of stereopsis:
• there are 6 types of stereopsis tests :
• 1.The Titmus stereotest
2.The Bernell stereo reinder test
3.The random dot E test
4. TNO Random dot test
5.Frisby test
6.Lang test

6. The Titmus stereotest :
• It is a contour stereotest . it is performed at a distance of 40
cms
• The Titmus test consists of 3D polarid vectograph consists of
two plates in the form of booklet viewed through polaroid
spectacles they are present right angle to each other .
• they have pictures like fly , circles ,animals .

7. The Random dot E test :
• The Random dot E stereotest is a vectograph consists of
demonstration plate and two test plates
• The demonstrated plates contain a raised E that can be seen by
anyone who has good acuity
• each of the test plates is printed with a polarized random dot
pattern and requires the use of polarized glasses
• A patient who has stereopsis will see a raised letter E in the
random dot pattern of one of the test plates ,where the other
plate is blank

8. Frisby test:
• The Frisby test consists of three transparent plastic
plates of varying thickness.
• On the surface of each plate are printed four squares of
a small randomly distributed shapes
• one of the squares contain a hidden circle
• the test doesn't require special spectacles because the
disparity is created by thickness of plate .
• the disparity measured is 600to 15 seconds of arc

9. lang test :
• The Lang test can be used to asses stereopsis in very young
children and babies who may reach out to touch the pictures
• it doesn't require special spectacles
• the targets are seen by alternately by each eye through build in
cylindrical lens element.
• displacement of dot creates disparity and the patient is asked to
name or point to a simple shape such as star ,on the card
• the degree of disparity is quite gross ranging 1200 to 600 seconds
of arc at 40cms

10. TNO random dot test:
• it consists of seven plates of randomly distributed paired
red and green dots which are viewed with red and green
spectacles
• within each plate the dots of one color forming the target
shape .
• the disparites measurment ranges from 19,80 to 15
seconds of arc
• it is tested at a distance of 40cm

11. The Bernell stereo reinder test:
• The bernell stereo reinder test it resembles titmus stereotest
• it is a polarized test proving stimuli for both gross and fine
stereopsis testing
• the test has the advantage that the examiner can make the
reinder's nose wiggle by rotating the picture slighly