clinically significant because of relatively small vertical vergence compensatory ranges

<1 prism diopters can be important

right or left hyperphoria (no hypo's)

can be mildly noncomitant

 

PREVALENCE

Scobee & Bennett: Maddox rod, 1500 patients

35% >= 1/2 prism diopters

"9% clinically significant symptoms"

 

SIGNS AND SYMPTOMS

blurred vision

diplopia

headache

varied location (frontal or occipital)

panoramic

being in a crowd

riding in a train or car

watching movies or TV

concentrating on sports activity

asthenopia

associated systemic problems

fatigue, back pain, vertigo, dizziness

nausea, motion sickness

anomalous head position

reduced binocular VA relative to monocular

narrow zone of SSBV

 

DIAGNOSIS

cover test

von Graefe

Maddox rod

fixation disparity

vertical vergence range asymmetry

O.D. supravergence 5/2

O.D. infravergence 3/1

 

primary gaze vs. downgaze

near point vs. distance

 

DIAGNOSTIC OCCLUSION

at home; in office

 

MANAGEMENT DECISION BASED ON:

symptoms

VDT use

uncorrected refractive error

accompanying accommodative or vergence anomaly

 

MANAGEMENT

vertical prism

neutralize the heterophoria

Rx 1/2 the heterophoria

 

balance the vertical vergence ranges

O.S. supravergence 6/2

O.S. infravergence 4/2

1 prism diopter BD O.S.

 

associated phoria

Rx 1/2 the associated phoria

 

prism adaptation

in-office trial period for 10-15 minutes

anisometropia

calculate the spectacle induced vertical prism

slab off (BU); slab on (BD)

 

orthoptics

some enlargement of vertical vergence ranges possible

usually in combination with prism