8.1.1: Assesses binocular status using objective and subjective measures

Question 1

What should a case history include to see if a px is binocular or having symptoms of problems?

Answer 1

Any double vision?
Any patching or lazy eye in yourself or immediate relatives?

Question 2

Describe fixation disparity?

Answer 2

• Heterophoria
  o Motor fusion is used to make object of regard single (incentive for fusion removed: eyes are dissociated)
• Fixation Disp:
  o Fusion (which is present) brings object within Panum’s fusional area, but not on horopter
  o Object is seen as single
   But with slight crossed disparity if in front of horopter
   With slight uncrossed disparity behind horopter
  o Useful is px has v small vertical that you may have missed on cover test
  o Can use pxs response to tell you where things are slipping
  o If old px and getting intermittent vertical diplopia – can add 1^ prism into glasses

Question 2

How do you assess a deviation accurately (BV)? What tests must you do?

Answer 2

• direction of latent or manifest deviation
• speed of recovery
• size –small/moderate or large
• concomitant/incomitant.
  Must conduct CT, motility & fix disp