Accommodation and Convergence Flashcards
What is the average AoA for a 5 year old? (D and cm)
5cm
15D
What is the average AoA for a 10 year old? (D and cm)
8cm
12.5D
What is the average AoA for a 20 year old? (D and cm)
10cm
9.75D
What is the average AoA for a 30 year old? (D and cm)
14cm
7.25D
What is the average AoA for a 40 year old? (D and cm)
25cm
4D
What is the average AoA for a 50 year old? (D and cm)
40cm
2.5D
What is the average AoA for a 60 year old? (D and cm)
80cm
1.25D
What is the average AoA for a 70 year old? (D and cm)
200cm
0.50D
What is the average AoA for a 75 year old? (D and cm)
infinity
0D
What is tonic accommodation?
Resting accommodation - when no stimulus at all (e.g. in the dark)
What is reflex accommodation?
Automatic accommodation in response to retinal blur, corrects for mismatch between proximal and vergence accommodation
What is vergence accommodation?
In response to convergence, only occurs if both eyes open
What is proximal accommodation?
In response to a stimulus, whether real or perceived
What does accommodative facility test?
Px’s ability to switch focus at different distances (i.e. ability to change amount of accommodation)
What is the normal result for accommodative facility for a px under 30?
Mono: 11 cycles/min
Binoc: 8 cycles/min
What does it mean when the binoc results are equal to mono results on accommodative facility?
They are suppressing one eye!
What does it mean when a px struggles to stimulate accommodation on the -2D lens during accommodative facility?
Accommodative insufficiency
What does it mean when a px struggles to relax their accommodation on the +2D lens during accommodative facility?
Overaccommodating - possibly latent hyperope
What is fusional convergence?
Stimulated by retinal disparity, corrects for phoria created by difference between proximal and accommodation vergence (occurs due to low AC/A ratio).
It’s the vergence needed to ensure binocular fixation
If this can’t compensate for a phoria, it will break down into a tropia
What is proximal convergence?
Stimulated by perceived or real stimulus closer than infinity
What is accommodative convergence?
Stimulated by accommodation
What is tonic convergence?
Baseline amount when there is no stimulus (physiologic position of rest due to muscle tonus)
What is an accepted normal NPC?
Less than 10cm
What prisms are used for vergence facility?
12BO and 3BI
What distance is vergence facility done at?
Near
What’s the normal result for vergence facility?
12-15 cycles/min
