Hess charts Flashcards
How does a Hess chart work?
Eyes are dissociated so that movements can be plotted in varying positions of gaze
What does the px need to have to be able to do a Hess chart?
NRC and BSV (ok if diplopia, but won’t work if suppression present)
What type of deviation will a Hess chart not plot?
Torsional
What are the types of Hess chart?
Electric Hess
Lees Screen (most common)
Computerised Hess
What does the greatest inward displacement on a Hess plot represent?
Primary underaction (palsied muscle)
What does outward displacement on a Hess plot represent?
Overaction
Why is it harder to tell which is the affected eye/primary muscle if muscle sequelae is longstanding?
Plots will look similar, over/underaction will be similar
How long does it take to get to the later stages of muscle sequelae?
After a few days
What does it mean if there’s a size difference of the deviation in different gazes?
Incomitance
Likely newer issue
What does it mean if the deviation is the same size in different gazes?
Concomitant deviation
Late stage incomitance with fully developed muscle sequelae
What do sloping Hess plots mean?
AV pattern likely present
What does a compressed Hess plot mean?
Likely mechanical restriction - flat across area of restriction
What is another characteristic of mechanical restrictions on a Hess plot?
Only the first stage of muscle sequelae will be present as it won’t develop any further.
