Binocular Single vision complete detail about how both eyes see a single image at the same time.

2. Binocular
Single Vision
(BSV)
Mutual coordination of both the eyes
To see a single image
Two images are usually formed on
the fovea of both the eyes, but we
see only one image
It is due to the Binocular Single Vision
Bi – 2
Ocular – Eyes
Normal when bi-foveal fixation

3. Retinal Correspondence
 Physiological relationship between both the eyes
 Two parts of Retina:
Nasal Retina
Temporal Retina
 Nasal Retina:
Gives temporal field vision of the same eye
 Temporal Retina:
Gives nasal field vision of the same eye

5. Retinal Correspondence
 The both the eyes are connected to each other at the
back on a point known as Optic Chiasm
 There is the decussation of the nasal retinas of both the
eyes
 The right eye carries the signal from the temporal retina of
same eye and the nasal retina of the left eye
 Similarly, the left eye carries the signal from the temporal
retina of same eye and the nasal retina of the right eye
 In simple words, Nasal retina of one eye corresponds to the
temporal retina of another eye

6.  These corresponding retinal elements projects in the same
direction in the space

7. Grades of Binocular Single Vision
Three (3) Grades of BSV:
Simultaneous perception
Fusion
Stereopsis

8. Simultaneous perception
 1st grade of BSV
 Ability to see two see 2 images
simultaneously
 1 formed on each retina
 2 dissimilar objects
 These images of the objects are not
super imposed
 Basic requirement of BSV
 Only possible through normal retinal
correspondence

9. Fusion
 2nd grade of BSV
 Ability to see two see 2 similar images
 1 formed on each retina
 These are then blend or fused to form one
 2 similar objects but incomplete

10. Stereopsis
 3rd grade of BSV
 Ability to see two see 2 slightly dissimilar
images
 1 formed on each retina
 These are then blend or fused to form one
with depth perception (3D) on basis of the
binocular disparity
 Binocular disparity is because both the eyes
sees the object from different location

11. Binocular
Disparity

12. Horopter
Horopter is an imaginary line in a
space
All points of which stimulate retinal
correspondence
Passes through the fixation object
which stimulates the fovea
Gives binocular single vision

13. Pannum's
Fusional Area Points Infront and behind the
horopter
Stimulate slightly non-retinal
correspondence points
After fixational disparity there is
binocular vision present

15. Physiological Diplopia
Normally, Binocular single vision is attained when
the object is at horopter
Without any abnormality or issue diplopia is
formed
Object that don't lie on the horopter will not
stimulate retinal corresponding points.
Thus there is physiological diplopia.

16. Abnormalities of BSV
Abnormality in BSV may be due to muscle weakness
or squint
The abnormalities in BSV can cause:
Confusion
 Pathological Diplopia

17. Confusion
2 dissimilar images superimposed on each other
simultaneously
When the eyes are misaligned, the dissimilar images
fall on the retinal corresponding points causing the
visual confusion

19. Pathological Diplopia
Occurs due to acquired misalignment of the visual
axis
Results in the image to fall one on foveal point of
one eye and the other on non-foveal point of the
other eye
2 Images seen