Accommodation & Vergence

ZCSBV

zone of clear & single binocular vision

AC/A ratio

ratio of accommodative convergence to accommodation; rotation of the eyes per diopter of accommodation

accommodative convergence

convergence that is driven by the accommodative system

disparity

when determining the AC/A ratio, _______ feedback is said to be open loop

CA/C ratio

ratio of convergence accommodation to convergence; accommodation per prism diopter of vergence

convergence accommodation

accommodation driven by the vergence system

accommodative

when measuring the CA/C ratio, _____ feedback is said to be open loop

too much convergence (eso)

when the AC/A ratio is too high, it implies that the pt has __________

too little convergence (exo)

when the AC/A ratio is too low, it implies that the pt has __________

gradient AC/A

• method of measuring the AC/A ratio

• measure the dissociated phoria w/ & w/o a -1.00D lens over the viewing eye

• one eye is occluded while the blur stimulus to accommodation is changed by 1.00D for the other eye

calculated AC/A

• method of measuring the AC/A ratio

• compare the change in phoria across a known change in viewing distance

• relies on the pt to make an accurate accommodative response

constant

once pt are able to complete AC/A testing, the ratio appears to be ______ with age until presbyopia

linear

the relationship between accommodation & vergence is _______ as long as you are within the range of where both systems can respond

increased

drugs that reduce the effect of the parasympathetic innervation result in a ________ AC/A

gradient CA/C

• method of measuring the CA/C ratio

• pt needs to fuse a target with no focus cues

• a prism is placed before an eye to drive vergence & the resulting uncorrected accommodative response can be measured with ret

3pd/D

what is the average stimulus AC/A ratio?

4pd/D

what is the average response AC/A ratio?

base in limit

1

phoria line

2

demand line

3

base out limit

4