OBJECTIVES

calculation of the accommodative demand for a particular fixation distance calculation of the convergence demand for a particular fixation distance

calculation of amplitude of accommodation calculation of amplitude of convergence (NPC)

Sheard's criterion

Percival's criterion

Morgan's normative analysis

calculate an AC/A ratio differences between gradient & calculated AC/A calculation of the PC/A ratio

positive relative convergence (or vergence) {PRC}

positive fusional convergence (or vergence) {PFC}

negative relative convergence (or vergence) {NRC}

negative fusional convergence (or vergence) {NFC}

positive relative accommodation (PRA)

negative relative accommodation (NRA)

Maddox's classification of vergence eye movements

- tonic

- accommodative

- fusional (disparity)

- proximal

vergence contributions to phoria measurements

the effect of added lenses and prisms on phoria, relative convergence and relative accommodation measurements

Classification of accommodation subcomponents

- tonic

- vergence

- blur driven (reflex)

- proximal

Proximal convergence

called the PC/A ratio, much like the AC/A ratio

an amount of convergence (from proximal cues) related to a fixed amount of accommodative demand

calculated by the difference between the near-far (calculated) AC/A and the gradient AC/A

e.g. near-far AC/A = 4/1 and gradient AC/A = 2/1

PC/A = 2/1

calculated AC/A has a component of PC/A + AC/A

 

Additional tests

stereopsis

lag of accommodation

facility of accommodation

facility of vergence

qualitative ocular motility

qualitative cover test

fixation disparity