Grades of BSV Flashcards
(20 cards)
What are the three grades of BSV?
Simultaneous perception, fusion, stereopsis
BSV refers to Binocular Single Vision
Define simultaneous perception.
The ability to appreciate two images at the same time, one formed on each retina
What is sensory fusion?
The ability to perceive 2 similar images, one formed on each retina, and interpret them as 1
What conditions must be met for sensory fusion to occur?
- Images must stimulate corresponding retinal areas
- Images must be of similar size
- Images must be of similar colour
- Images must be of similar luminosity
- Images must be in focus
Define motor fusion.
The ability to maintain sensory fusion through a range of vergence movements
What are vergence movements?
Disjugate movements of the eyes, such as convergence or divergence
What is the motor fusion amplitude?
The amount of motor fusion, can be measured horizontally and vertically
What is retinal rivalry?
Dissimilar contours presented to corresponding retinal points, fusion becomes impossible
What is stereopsis?
The relative depth of objects on the basis of binocular disparity
What causes stereopsis?
Sensory fusion of two slightly different images perceived by each eye due to horizontal separation
What are crossed disparities?
Objects are in front of the horopter in Panum’s space
What are uncrossed disparities?
Objects are behind the horopter in Panum’s space
At what age does stereopsis develop in humans?
Between 3-4 months of age
What is stereoacuity?
The measurement of the minimum disparity giving rise to stereopsis, measured in seconds of arc
List some clinical stereotests.
- Lang’s two pen test
- Synoptophore
- TNO
- Titmus/Wirt
- Frisby
- Randot
- FD2
- Braddick slides
What is motion parallax?
The apparent motion of objects relative to us as we move or shift our head
Define size constancy.
Our perception of the size of objects remains relatively constant despite variations in retinal size
What is linear perspective?
A system for creating an illusion of depth where parallel lines converge at a vanishing point
What is aerial perspective?
The technique of depicting distant objects as paler, less detailed, and usually bluer than near objects
What is the significance of motor fusion in management?
It indicates the ability to maintain sensory fusion, impacting treatment strategies
