Entrance Test (cont.) Flashcards
What does the sensory system do for binocular vision?
Constructs single perception from 2 retinal images
What does the motor system do for binocular vision?
Vergence and eye movements!
Coordinates with the accommodative system to maintain a clear image.
Poor binocular vision leads to:
Fatigue
eye strain
Headaches
Binocular vision is in jeopardy in:
Eye disease
Strabismus
Trauma
What is stereopsis?
An indicator of binocularity. The sensory and motor fusion of vision
Also shows if accommodative and vergence systems are working well
What is the term for the sensory and motor fusion of vision?
Binocularity
What is fusion?
How the eyes unite!
The 3 degrees of fusion
- Simultaneous perception and superimposition
- Flat fusion
- Stereopsis
To get stereopsis, binocularity must be..
Excellent to fire fine disparity
Purpose of stereopsis
To measure fine depth perception by evaluating the ability to fuse stereoscopic targets
Equipment for stereopsis
Polaroid glasses and stereo book
Testing distance for stereopsis is at:
40 cm with an overhead lamp
For adults, stereopsis procedure consists of:
direct patient to page 2 with the smallest targets.
Start with first box, ask pt to identify the non floating circle
Repeat for all 12 boxes or until pt misses 2 in a row
Record level of stereopsis
If the pt is unresponsive or does not appreciate stereo…
Use medium targets
If the pt gets all the medium targets…
Try small targets again
If pt cannot identify medium or small targets…
Use large, duh
Recording Stereopsis
Record stereo at N
Record test used
Indicate with or without correction
Recorded in seconds of arc
Ex. Stereo at N cc 400 seconds of arc Stereo E
When is Worth 4 Dot used?
When stereopsis is below normal.
What is Worth 4 Dot for?
To assess flat fusion at distance and near. Ability to detect a small central scotoma at near
W4D procedure
Tell pt to look at W4D target with the red top on top and white on bottom.
Ask pt how many dots they see
With 5 dots, ask where the red and green dots are located. This determines the location of the visual axes
W4D results (# of dots)
- Red dots, only red eye is used, OS suppression
- Green dots, only is sees, OD is suppresion
4: normal flat fusion - Diplopia
