Convergence Excess

DEFINITION:

A sensorimotor anomaly of the binocular visual system characterized by a tendency for the eyes to over-converge at near.

SIGNS AND SYMPTOMS:

The signs and symptoms associated with convergence excess may include, but are not limited to, the following:

1. reduced efficiency and productivity/diminished accuracy/inconsistent work product
2. diminished performance with time on task
3. diplopia (ICD: H53.2)/tendency to close or cover one eye
4. transient blurred vision/illusory movement
5. loss of place, repetition and/or omission of words and/or lines of print while reading
6. transpositions when copying from one source to another
7. pain in or around the eye (ICD: H57.13)
8. headaches (ICD: R51)
9. difficulty sustaining near visual function
10. avoidance of visually demanding tasks
11. inaccurate eye-hand coordination
12. abnormal postural adaptation/abnormal working distance (ICD: R29.3)
13. spatial disorientation
14. photophobia (ICD: H53.149)
15. inconsistent visual attention/concentration and/or awareness
16. distractibility while performing visually demanding tasks
17. general fatigue (ICD: R53.83)
18. awareness of the need for volitional control of eyes
19. asthenopia (ICD: H53.149)
20. difficulty changing fixation from near to far

DIAGNOSTIC FACTORS:

Convergence excess encompasses one or more of the following diagnostic findings:

1. near esophoria significantly greater than distance phoria
2. high AC/A ratio
3. restricted negative vergence ranges at near
4. low negative fusional vergence flexibility
5. eso fixation disparity at near
6. low positive relative accommodation (PRA)
7. steep base-in component of the forced vergence curve

 

THERAPEUTIC MANAGEMENT CONSIDERATIONS:

The doctor of optometry determines appropriate diagnostic and therapeutic modalities, and frequency of evaluation and follow-up, based on the urgency and nature of the patient’s conditions and unique needs. Vision disorders that are not totally cured through vision therapy may still be ameliorated with significant improvement in visual function and quality of life. The management of the case and duration of treatment would be affected by:

1. the severity of symptoms and diagnostic factors, including onset and duration of the problem
2. the complications of associated visual conditions
3. implications of patient’s general health, cognitive development, physical development, and effects of medications taken
4. etiological factors
5. extent of visual demands placed upon the individual
6. patient compliance and involvement in the prescribed therapy regimen
7. type, scope, and results of prior interventions

PRESCRIBED TREATMENT REGIMEN:

Some cases are successfully managed by the prescription of therapeutic lenses and/or prisms. Most convergence excesses require optometric vision therapy, which incorporates the prescription of specific treatments in order to:

1. reduce nearpoint esophoria
2. enhance and develop fusional vergence ranges, stability, and flexibility
3. enhance accommodative/convergence relationships
4. integrate binocular function with information processing
5. integrate binocular skills with accurate motor responses
6. integrate binocular skills with other sensory skills (vestibular, kinesthetic, tactile, and auditory)
7. increase visual stamina/integrate newly established skills with information processing

DURATION OF TREATMENT:

The following treatment ranges are provided as a guide. Treatment duration will depend upon the particular patient’s condition and associated factors. When duration of treatment beyond these ranges is required, documentation of the medical necessity for additional treatment services may be warranted for third-party claims processing and review purposes.

1. The most commonly encountered convergence excess usually requires 24 hours of office therapy.
2. Convergence excess may require substantially more office therapy, if complicated by associated factors such as cerebral vascular accident, head trauma, and/or systemic conditions.

FOLLOW-UP CARE:

At the conclusion of the active treatment regimen, periodic follow-up evaluation is required. Should signs, symptoms, or other diagnostic factors recur, further therapy may be medically necessary. Therapeutic lenses may be prescribed during or at the conclusion of active vision therapy to assist in the maintenance of long-term stability.