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hess and diplopia chart

Key Concepts:

Terms in this set (47)

General guidelines
i. The central dot in each field indicates the deviation in the primary position.
ii. Smaller field belongs to the paretic eye.
iii. Inward displacement of the dots indicates underaction. The eye cannot move far enough to plot in normal position.
iv. Outward displacement of dot indicates overaction (or contracture).
Excessive movement of eye causes dots to be plotted beyond the normal position. Equal sized fields indicate that muscle sequelae have developed. Underaction of the affected muscle, overaction of the contralateral synergist, contracture of ipsilateral antagonist of paretic muscle, secondary underaction of the contralateral synergist of contracted muscle. The paresis is therefore long standing or congenital.
vi. The outer fields should be examined for small under and overactions which may not be apparent on inner fields.
vii. If the outer field is very close to the inner field, a mechanical cause for the limited movement is likely.
viii. Each small square subtends 5°. The inner square therefore measures 15° movement from the primary position to each position of gaze. The outer square measures 30° of movement.
ix. When the right eye fixes the red dots, the field of movement of the left eye is plotted and vice versa. The fixing eye determines the amount of innervation sent to non-fixing eye.

Interpretation of Hess chart.
i. Compare the size of the two fields.
ii. Examinethesmallerfield(pareticeye)andnotepositionofmaximum
inward displacement which will be in the direction of main action of
paretic muscle.
iii. In the side with smaller field, note if there is outward displacement
in the direction of action of the ipsilateral antagonist of the affected muscle. Outward displacement indicates contracture shown as overaction.
iv. Examine the larger field and note position of maximum outward displacement, indicating overaction of contralateral synergist of paretic muscle.
v. In the side with larger field, note if there is inward displacement of the antagonist of the overacting muscle, indicating secondary underaction (this muscle is contralateral synergist of the contracted muscle).
vi. Look at the relationship between the inner and outer field.
vii. Look at the position of center dots inward displacement indicating
viii. Equal sized fields indicate either symmetrical limitation of movement in both eyes or a concomitant strabismus.
ix. Sloping fields denote A or V pattern.