Visual Deprivation Nystagmus

DEFINITION:

Visual deprivation nystagmus is an ocular nystagmus which is attributed to early onset, reduced, central visual acuity.

 

SIGNS AND SYMPTOMS:

The symptoms and signs associated with visual deprivation nystagmus may include, but are not limited to, the following:

1. reduced corrected vision
2. head turn/tilt
3. pendular nystagmus with irregular eye movements
4. defective stereopsis and/or depth judgment; inaccurate spatial judgments
5. abnormal postural adaptations and/or working distances
6. incoordination and clumsiness
7. asthenopia
8. sensation of target movement
9. general fatigue
10. diminished accuracy with increased task time
11. motion sickness
12. dizziness after sustained visual tasks

 

DIAGNOSTIC FACTORS:

Although additional diagnostic tests may be performed to rule out other causes (i.e. refractive, other types of nystagmus, psychogenic, and other structural/pathological defects) of reduced visual acuity and reduced visual performance, visual deprivation nystagmus is characterized by and/or associated with one or more of the following findings:

1. reduced best corrected visual acuity
2. absence of fusion and/or reduced fusion ranges
3. reduced stereopsis
4. suppression
5. inaccurate visual-motor coordination
6. oscillopsia, under monocular conditions
7. pendular nystagmus with irregular eye movements
8. strabismus
9. oculomotor dysfunctions

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. In cases of visual deprivation nystagmus, co-management with medicine (i.e. neurologists, neuro-ophthalmology and/or ophthalmology) is often in order due to systemic complications. 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. Many visual deprivation nystagmus cases benefit from optometric vision therapy, which incorporates the prescription of specific treatments in order to:

1. improve visual fixation (thereby improve visual acuity), smooth pursuits, and saccades monocularly and then binocularly
2. develop adequate fusional vergence ranges and stability in all positions of gaze at distance and near
3. enhance accommodative/convergence relationships
4. enhance depth judgments and/or stereopsis
5. integrate binocular function with information processing
6. enhance fusional vergence facility and flexibility
7. integrate binocular skills with accurate motor responses
8. integrate binocular skills with other sensory skills (vestibular, kinesthetic, tactile, and auditory)
9. 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. Full treatment requires resolution of associated visual
2. The most commonly encountered visual deprivation nystagmus usually requires 28 to 40 hours of office therapy.

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.