Convergence insufficiency:

incidence, diagnosis, and treatment

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

ABSTRACT — Convergence insufficiency is one of the most common ocular problems. The paper carefully reviews the existing literature paying particular attention to etiology, diagnosis, sensory findings, treatment, and treatment results.

KEY WORDS—Convergence insufficiency, accommodation, near point, phoria, fusional convergence, vision training

Convergence insufficiency (CI), as it has been described in the literature, is a syndrome consisting of a receded near point of convergence, exophoria at near, reduced positive relative convergence, and reduced negative relative accommodation.’ However, since few patients manifest all four characteristics in their presentation of symptomatology, few clinicians define CI in this manner. In fact none of the authors cited in this paper employ this definition. Generally CI is defined as a reduction in the positive relative convergence in relationship 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 undesirable symptomatology, a literature review is both warranted and important in order to dispel inappropriate clinical impressions and to reaffirm a basic understanding of this binocular anomaly.

Incidence

Clinical studies show a large difference in incidence of convergence insufficiency. These differences 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 symptoms. 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 under by Mahto;6 and 1.75% by Norn.7

“The near phoria measurement is the amount of accommodative and tonic convergence in

use at a given distance.”

Many authors feel that convergence insufficiencies are not of significant importance in children since symptoms do not appear 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 specific about symptoms, cannot relate them to function, and may avoid symptom-producing tasks. It is interesting to note that Allen et al10 found that approximately 5% of a school population, 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 similar to the percentages of young adults presenting symptoms. Perhaps the children who demonstrate objective signs of a convergence 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, However, the etiology here may be different than in a younger population where the individuals still have the use of accommodative convergence. Presbyopes who

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