What are the two suppression tests?
Worth 4 dot
4 prism base out
What are the 3 degrees of fusion?
- Simultaneous perception and superimosition
- Flat fusion
- Stereopsis
What is flat fusion?
Fusion of the binocular images without the perception of depth
How do you test for level 3 fusion (stereopsis)?
Using Randot stereo test
When using Randot, when should you suspect suppression or central scotoma?
If the result is less than 40 seconds of arc
What test is used for flat fusion (level 2 fusion)?
Worth 4 dot
With flat fusion, is diplopia present?
No
The red filter of the red/green glasses goes over which eye?
Right
With a normal patient using the Worth 4 dot, if the patient is covering their left eye, what should they see?
2 red dots
With a normal patient using the Worth 4 dot, if the patient is covering their right eye, what should they see?
3 green dots
With the Worth 4 dot, if flat fusion is present, what should the patient report seeing if neither eye is covered?
4 dots, but depending on dominance, they may see a different combination of colors
How is the Worth 4 dot test used to test for a binocular central suppression/scotoma?
Starting at 40 cm with flat fusion, slowly move away until there is a chang in the number of dots seen.
- If the dots reappear under monocular conditions, there is a scotoma under binocular conditions
- If the dots do not reappear, the scotoma is unilateral
What does the 4 prism base out test check for?
Central suppression scotoma
What is the normal response to the 4 prism base out test?
- Concomittant movement outwards (version)
2. Refixation inwards (vergence)
What accounts for the concomittant movement outwards with the 4 prism base out test?
Hering’s law of equal innevation
What are abnormal responses to the 4 prism base out test?
- Neither eye moves in response to the prism - suppressing the eye with the prism; no compensating movements
- The concomittant eye show a version, but not a vergence
