1. Projection in Heterotropia
Helen Griffiths
Year 1
October 2016

2. The plan for today….. Projection in normal BSV – recap
Types of strabismus
Projection in strabismus
Consequences of strabismus

3. Normal retinal correspondence
Fovea
Has the principal visual direction (PVD)
Projects straight ahead
Corresponds to the fovea of the other eye
Nasal retina
Projects temporally
Nasal retina RE corresponds with temporal retina of LE
Temporal retina
Projects nasally

4. Normal binocular single vision

5. Normal binocular single vision

6. Heterotropia
A condition in which one or other visual axis is not directed towards the fixation point

7. Types of Heterotropia
Esotropia - One eye deviates nasally when both eyes are open
Exotropia – One eye deviates temporally when both eyes are open

8. Types of Heterotropia
Hypertropia - One eye is deviated upwards when both eyes are open
Hypotropia – One eye is deviated downwards when both eyes are open

9. Projection in heterotropia
Diplopia
Results from stimulation of non-corresponding retinal points by a single object
Confusion
Results from stimulation of corresponding points in the two eyes by different objects

10. Esotropia

11. Esotropia

12. Esotropia
Image from right eye
on the right side

13. Esotropia Homonymous (uncrossed) diplopia
Image from an esotropic eye is seen on the
same side
eg. Right esotropia image from right eye seen on the right hand side

14. Exotropia Heteronymous (crossed) diplopia
Image from an exotropic eye is seen on the
opposite side
eg. Right exotropia image from right eye seen on the left hand side

15. Draw the following:
Projection diagram: Right XT with normal retinal correspondence

16. Vertical heterotropia
Hypertropia
Object of fixation stimulates superior retina of the deviating eye which projects inferiorly
Diplopic image from the deviating eye seen below the real target (seen by fixing eye) RE S F
cerebral projection RE

17. Vertical heterotropia
Hypotropia
Object of fixation stimulates inferior retina of the deviating eye which projects superiorly
Diplopic image from the deviating eye seen above the real target (seen by fixing eye) F I RE F I
cerebral projection RE

18. Adaptations To avoid diplopia and confusion Suppression
Abnormal correspondence

19. Suppression The mental inhibition of visual sensations
Occurs more readily in children
Foveal (central) suppression eliminates confusion
Nasal / temporal (peripheral) suppression eliminates diplopia

20. Abnormal correspondence
Sensory adaptation which allows strabismic patients to use both eyes without diplopia or confusion
Achieve abnormal binocular single vision
Further details in semester 2

21. Summary
Diplopia results from stimulation of non-corresponding retinal points by the same object
Confusion results from stimulation of corresponding points by different objects
Homonymous pathological diplopia occurs in esotropia
Heteronymous pathological diplopia occurs in exotropia

22. To do
Read Von Noorden & Campos - chapter 13 p211 – NB: 220 – 231 on line
Library or