Divergence excess is a specific type of binocular vision disorder characterized by an excessive outward deviation of the eyes when looking at objects in the distance. Here are the key aspects of divergence excess:
Divergence
excess refers to a condition where the eyes have an exaggerated exodeviation
(outward deviation) during distance fixation, which is greater than the
deviation observed during near fixation. It is a form of intermittent
exotropia.
The
exact cause of divergence excess is not fully understood. However, it is
believed to be related to an imbalance in the extraocular muscles responsible
for eye movement and alignment. The condition may be associated with abnormal
innervation, muscle weakness or overaction, or issues with the neural control
of eye movements.
Exodeviation:
Divergence excess is characterized by an exodeviation (outward deviation) of
the eyes that is more pronounced at distance fixation compared to near
fixation. The deviation typically increases when the patient looks into the
distance and may be intermittent.
Variable Deviation:
The exodeviation may vary in magnitude, with some patients experiencing a large
deviation and others having a smaller deviation.
Normal Near Vision:
Near vision is typically maintained without significant deviation or symptoms,
and the exodeviation is primarily observed at distance fixation.
Diplopia (Double
Vision): Some patients with divergence excess may experience
diplopia or double vision, particularly when looking at distant objects.
Diagnostic Tests:
Cover Test:
A cover test is performed to assess the alignment of the eyes during distance
and near fixation. It helps identify the exodeviation and any deviation changes
between the two conditions.
Prism Bar Test:
Prism bar testing can determine the amount of exodeviation and assess the
near-to-distance disparity in eye alignment.
Binocular Vision
Assessment: A
comprehensive evaluation of binocular vision function is important to rule out
other related conditions and assess the overall binocular visual system.
Treatment:
The
treatment of divergence excess aims to improve eye alignment, reduce diplopia,
and optimize binocular vision. It may include:
Prism Glasses:
Prescribing prism glasses can help align the eyes and reduce diplopia.
Vision Therapy:
Vision therapy exercises can be employed to strengthen eye coordination and
improve the control of eye movements.
Surgery:
In some cases, surgical intervention may be considered to correct the excessive
exodeviation. The specific surgical approach will depend on individual factors
and may involve muscle weakening or strengthening procedures.
The
treatment approach for divergence excess should be individualized based on the
severity of the condition, the presence of associated symptoms, and the
patient's specific visual needs and goals. It is essential to consult an eye
care professional, typically a pediatric ophthalmologist or strabismus
specialist, for a comprehensive evaluation and personalized treatment plan.
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