Hess chart , its uses and interpretation.

1. Hess chart and it’s
interpretation
Azmat Khan
Lecturer: The University Of
Lahore Islamabad Campus

2. Walter Rudolf Hess
(March 17, 1881 – August 12, 1973)
Swiss physiologist
Devised Hess chart in 1908
Won the Nobel Prize in 1949 for mapping the areas of
the brain involved in the control of internal organs.

3. Hess screens

4. Equipment

5. General Principle
 Principle is haploscopic.
 Chart is plotted based on the Herring's and
Sherrington’s law of innervations.
 Dissociation of two eyes by means of colors.

6. Requirements
 Full understanding about what he is supposed to
do, since the test is purely subjective.
 Good vision in both eyes.
 Foveal projection in the presence of normal retinal
correspondence.

7. • Patient must have NRC
• Little or no suppresion
• Color blind can’t appreciate red and green

8. Method
 Test is performed with each eye
fixating in turn.
 It is done at 50 cm.
 Patient wears red and green
glasses.
 Eye to be tested should have green
glass in front of it.
 The chart has electronically
operated board with small red
lights.
 Patient is asked to place green
light in each of points on red light
as illuminated.
 Next the goggles are changed.

9. o Compression of space between the two plotted fixation
points indicates underaction of a muscle acting in that
direction.
o Expansion indicates overaction.
o Smaller field belongs to eye with paretic muscle.
o Unaffected eye shows larger field expressing the overaction
of the contralateral synergist.
o Fields of similar shape and size seen in comitant deviation,
while dissimilar shape and size indicate incomitance.
Interpretation

11. Hess chart

12. Sequelae of extra ocular muscle
palsies
a. Overaction of the contralateral
synergist
b. Overaction of the ipsilateral
antagonist
c. Secondary underaction of the
contralateral antagonist

13. Procedure
• Patient is seated 50 cm from the screen, holding a
pointer projecting green light and wearing red and
green goggles
• The screen has red lights in different positions of
gaze, illuminated by the examiner, one at a time
• Patient is asked to superimpose each illuminated
red light on the screen with the green light of his
pointer

14. Procedure
contd.
• The point where the patient projects the green
light is recorded by the examiner on a paper
chart which is a miniature copy of the screen
• After all the points are recorded, they are joined
by straight lines
• The goggles are now reversed and the procedure
repeated
• Each chart thus plotted belongs to the eye
behind the green filter

15. Uses
• Assessment of incomitant strabismus
• Identification of the affected eye
• Identification of the underacting and overacting
muscles
• Measurement of deviation (each small square=5
degrees)
• Differentiation between recent onset and long
standing strabismus (development of muscle
sequelae)

16. Uses contd
• Differentiation between mechanical and
neurogenic strabismus (mechanical fields are
compressed)
• Identification of A and V phenomenon
• Monitoring progress
• Selection of muscles for surgery
• Assessment of outcome of treatment
• Charting the field of binocular single vision

17. Interpretation
Compare the two charts for:
Size
Position
Shape

18. Size
• Determine which is the smaller field
(belongs to the affected eye)
• Determine the underacting muscle/s
(inward displacement of spots on the chart)
• Determine the overacting muscle/s
(outward displacement of spots on the chart)
• Determine if the problem is recent or long
standing
• Differentiate between mechanical and neurogenic
pathology
• Look at the outer fields for minor problems which
may not be noticeable in the inner fields

19. Position
• Determine the displacement of the central spot
on the chart and measure it for hyper, hypo, exo
or eso deviation
(one small square=5 degrees)

20. Shape
Sloping fields signify A and V phenomena

21. Examples of Hess charts that may be
encountered in the examination
Neurogenic causes Mechanical
causes
Third nerve palsy Orbital floor fracture
Fourth nerve palsy Duane's syndrome
Sixth nerve palsy Brown's syndrome
Thyroid eye disease

22. Example
What is the primary position of the affected eye?

23. Example
What is the primary position of the affected eye?
Ans. The right eye is hypo and exotropic.

24. Example contd.
What is the diagnosis?

25. Example contd.
What is the diagnosis?
Ans. Right 3rd nerve palsy.

26. Example
What type of abnormality is seen in this patient?

27. Example
What type of abnormality is seen in this patient?
Ans. A mechanical one as the field of the affected left eye is
compressed.

28. Example
contd.
In which direction is the affected eye likely to be restrited?

29. Example
contd.
In which direction is the affected eye likely to be restrited?
Ans. Up and down gaze.

30. Example
contd.
What is the diagnosis?

31. Example
contd.
What is the diagnosis?
Ans. Left orbital floor fracture.

32. Example
Which is the abnormal eye?

33. Example
Which is the abnormal eye?
Ans. The right eye , as shown by the smaller field.

34. Example contd.
Which muscle is underacting?

35. Example contd.
Which muscle is underacting?
Ans. The right lateral rectus.

36. Example contd.
Which muscle is overacting?

37. Example contd.
Which muscle is overacting?
Ans. The left medial rectus.

38. Example contd.
What is the diagnosis?

39. Example contd.
What is the diagnosis?
Ans. Right sixth nerve palsy.

40. Example
Which is the abnormal eye?

41. Example
Which is the abnormal eye?
Ans. The left eye. (note the smaller field)

42. Example
contd.
Which muscle is underacting?

43. Example
contd.
Which muscle is underacting?
Ans. The left superior oblique.

44. Example
contd.
Which muscle is overacting?

45. Example
contd.
Which muscle is overacting?
Ans. The right inferior rectus.

46. Example
contd.
Is this a long-standing palsy?

47. Example
contd.
Is this a long-standing palsy?
Ans. No, the muscle sequelae have not fully developed.

48. Example
contd.
What is the diagnosis?

49. Example
contd.
What is the diagnosis?
Ans. Left superior oblique palsy.

50. Example
Which muscle is underacting?

51. Example
Which muscle is underacting?
Ans. The right inferior oblique.

52. Example contd.
Which muscle is overacting?

53. Example contd.
Which muscle is overacting?
Ans. The left superior rectus.

54. Example contd.
What is the diagnosis?

55. Example contd.
What is the diagnosis?
Ans. Right Brown syndrome. The Hess chart is typical. The
affected field is abnormal superiorly but normal inferiorly

56. Thankyou