NON-STRABISMIC VERTICAL IMBALANCE

    I.  INTRODUCTION

    Clinical Issues

1. relatively small vertical vergence compensatory ranges

a. expected 3/1 supra- & infra-vergence range

2. <1 prism diopters can be important

3. can be mildly noncomitant and unnoticed

4. usually screened at distances

5. by convention: right or left hyperphoria (no hypo's)

II. PREVALENCE

    Scobee & Bennett: Maddox rod, 1500 patients (from St. Louis)

      35% > 1/2 prism diopters

      "9% clinically significant symptoms"

 

III. SYMPTOMS

    1. asthenopia, pulling sensation

    2. headache

    a. varied location (frontal or occipital)

    b. panoramic

    i. being in a crowd

    ii. riding in a train or car

    iii. watching movies or TV

    iv. concentrating on sports activity

3. diplopia, vertical

    4. blurred vision

    5. history of unsatisfactory prescriptions

    6. loss of place with reading

    7. associated systemic problems

    a. back-neck pain

    b. vertigo, dizziness, nausea, motion sickness (see 2b)

and SIGNS

    6. anomalous head position

    7. reduced binocular VA relative to monocular

    8. narrow zone of SSBV

 

IV. DIAGNOSIS

    1. cover test

    2. Flip-prism test of Eskridge

    3. phorometry

      a. von Graefe

      b. Maddox rod

      c. modified Thorington

    4. vertical vergence range asymmetry

    e.g. O.D. supravergence 5/2 : O.D. infravergence 3/1

      (suggests 1 PD OD hyperphoria)

5. fixation disparity

 V. OTHER DIAGNOSTIC FACTORS

    6. primary gaze vs. downgaze

    7. near point (midline convergence) vs. distance

    8. diagnostic occlusion (of Roy) - at home; in office

VI. MANAGEMENT DECISIONS BASED ON:

    1. symptoms

    2. VDT use

    3. uncorrected refractive error

    4. accompanying accommodative or vergence anomaly

 

VII. MANAGEMENT

    1. vertical prism (slab off (BU); slab on (BD), Fresnel)

    a. neutralize the heterophoria

        i. Rx 1/2 the heterophoria

     

      b. balance the vertical vergence ranges

      i. O.S. supravergence 6/2 : O.S. infravergence 4/2

          1 prism diopter BD O.S.; Rx 1/2 the amount

       c. associated phoria

        i. Rx 1/2 the associated phoria

      2. orthoptics

      a. some enlargement of vertical vergence ranges possible

      b. always in combination with vertical prism

VIII. OTHER MANAGEMENT ISSUES

    1. prism adaptation

    a. in-office trial period for 10-15 minutes

    2. anisometropia

    a. calculate the spectacle induced vertical prism