Binocular Vision Anomalies Quiz

Binocular Vision Anomalies

• Anomalies can affect the bony orbit, ocular muscles, or nervous system due to congenital issues or acquired through accident or disease.
• Even if the motor system is anatomically normal, functional anomalies may disrupt binocular vision, potentially caused by diseases like excessive accommodation from uncorrected hypermetropia leading to excessive convergence.
• Conditions that can impact the motor system include hemorrhages affecting nerve supply, intracranial pressure changes, and abnormal growths in intracranial tissue; early recognition and medical intervention are crucial.
• Sensory anomalies can stem from:
  • Loss of optical clarity in one or both eyes.
  • Image size discrepancies between eyes (aniseikonia).
  • Anomalies in visual pathways or cortex.
  • Issues in the coordinating mechanism of the motor system, possibly leading to adaptations or anomalies in the sensory system, such as suppression or abnormal retinal correspondence.

Position of Eyes

• Adequate anatomical, motor, and sensory systems are essential for normal binocular vision.
• Human eyes typically look forward.
• In normal conditions, eyes are nearly parallel, termed the position of anatomical rest.
• Muscle tone and postural reflexes usually adjust the visual axes to be less divergent, referred to as the position of physiological rest.

Physiological Factors

• Accommodation-Convergence Relationship: Convergence of eyes occurs when accommodation is exerted, known as accommodative convergence.
• Fusion and Divergence: Final adjustments for binocular vision involve fusional (disparity) vergence to align retinal images.
• If fusional vergence is suspended, like covering one eye, eyes adopt a dissociated position, distinct from the active position where all factors are functioning.