7. Convergence Flashcards
What is convergence?
The simultaneous rotation of both eye inwards
How can you measure near point of convergence accurately
RAF rule- dot on a line for fixation, high contrast helps recognising diplopia
How is NPC measured inaccurately?
Pen to nose or finger to nose technique cus finger is chunky
What unit is NPC recorded in?
cm
When should patient wear correction and why?
High hypermetropes, high myopes and presbyopes should wear rx as it’s at near
What lenses assist convergence and why?
Minus lenses stimulate accommodation, induce base in prism so assist convergence
bare confusing
What instruction do you give to px when measuring NPC?
Can you look at this line, I am going to bring it closer towards you, tell me when it turns into 2, not when it blur but when its double then pull the target away from px and watch for fusion
What do you record?
Record break point when its double and record recovery point
How do you hold the RAF rule when measuring NPC?
In a depressed angle
How many times do you do npc?
3 x
What is normal value of npc dependant on?
Age and targret
What is the normal value for npc for a pre presbyope?
<6cm break point
7cm recovery point
What is the normal value for npc for a presbyope?
15cm
How do you record results?
with rx, in cm, which eye diverged with dipl-meaning if they reported diplopia)
What’s the difference between subjective and objective npc measurement?
Subjective is if they reported diplopia
Objective is you watching which eye diverges
