Convergence insufficiency:

incidence, diagnosis, and treatment

JEFFREY COOPER, O.D.; ROBERT DUCKMAN, O.D.

ABSTRACT — Convergence insuffi-

ciency is one of the most common

ocular problems. The paper carefully

reviews the existing literature paying

particular attention to etiology, diag-

nosis, sensory findings, treatment,

and treatment results.

KEY WORDS—Convergence in-

sufficiency, accommodation, near

point, phoria, fusional conver-

gence, vision training

Convergence insufficiency (CI),

as it has been described in the

literature, is a syndrome consist-

ing of a receded near point of

convergence, exophoria at near,

reduced positive relative conver-

gence, and reduced negative rela-

tive accommodation.’ However,

since few patients manifest all

four characteristics in their pre-

sentation of symptomatology,

few clinicians define CI in this

manner. In fact none of the au-

thors cited in this paper employ

this definition. Generally CI is

defined as a reduction in the pos-

itive relative convergence in rela-

tionship to the demand and/or

the reduction in the near point of

convergence, i.e., a deficiency in

fusional, tonic, accommodative

and/or voluntary convergence.

Since this condition is relatively

common and• may cause abnor-

ma! visual behavior and undesir-

able symptomatology, a litera-

ture review is both warranted

and important in order to dispel

inappropriate clinical impres-

sions and to reaffirm a basic un-

derstanding of this binocular

anomaly.

Incidence

Clinical studies show a large

difference in incidence of conver-

gence insufficiency. These differ-

ences may be attributed to the

definitions of CI being used, the

populations being studied and

methods of measurement.

CI has been said to occur in

1% of normal children and 15%

of adults,² Kratka has found that

25% of a sample of 500 patients

demonstrated findings indicative

of CI.3 Seventy-five percent of

these patients exhibited symp-

toms. Other findings include:

2.8% by White and Brown;⁴

2.5% by Maun; between 3.1%

and 4.9% by Kent and Steeve;⁵

11% of patients aged 40 and un-

der by Mahto;⁶ and 1.75% by

Norn.⁷

“The near phoria mea-

surement is the amount

of accommodative and

tonic convergence in

use at a given distance.”

Many authors feel that conver-

gence insufficiencies are not of

significant importance in chil-

dren since symptoms do not ap-

pear until the second or third

decade of life.^3,7,8,9 During this

period young adults are involved

with the greatest amount of near

point work, and will seek help to

alleviate symptoms. Children, on

the other hand, do not utilize

their eyes as much on near point

activities and, therefore. may not

experience any discomfort. In

addition, children are less spe-

cific about symptoms, cannot re-

late them to function, and may

avoid symptom-producing tasks.

It is interesting to note that Al-

len et al10 found that approxi-

mately 5% of a school popula-

tion, between kindergarten and

6th grade, had a reduced near

point of convergence and 6% of

the children failed a near cover

test. These percentages are simi-

lar to the percentages of young

adults presenting symptoms.

Perhaps the children who demon-

strate objective signs of a con-

vergence insufficiency earlier in

life, do not experience symptoms

until later on, when the visual

demands placed upon them are

sufficiently stressful to produce

discomfort.

Presbyopes also demonstrate

convergence insufficiency, How-

ever, the etiology here may be

different than in a younger popu-

lation where the individuals still

have the use of accommodative

convergence. Presbyopes who

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