Introduction to Binocular Vision and Eye Movements

These flashcards cover key concepts of binocular vision and eye movements, including definitions, mechanisms, and clinical significance related to visual function and management.

What is Binocular Vision?

The simultaneous use of two eyes to give one image in the brain.

What influences the view of skittles in Binocular Vision?

The view from each eye is slightly different.

What is Binocular Single Vision (BSV)?

The ability to perceive two images simultaneously, one from each eye, as a single image.

What occurs if you do not have Binocular Single Vision?

Double vision, or diplopia may occur.

What needs to happen for Binocular Single Vision?

The eyes must be in focus, aligned, and transmit clear images to the brain.

What is Normal Retinal Correspondence (NRC)?

A condition where corresponding retinal points in both eyes have a common visual direction.

What is cyclopean projection?

The brain perceives a single image as if there was a single eye in the middle.

What is the horopter?

An imaginary line where all objects stimulate corresponding retinal points.

What is Panum's fusional space?

An area around the horopter where corresponding objects can still be seen as single.

What happens outside Panum's fusional space?

Diplopia occurs, causing double vision.

What types of diplopia can occur?

Physiological diplopia and pathological diplopia.

What are Worth's Grades of Binocular Vision?

Stereopsis, sensory fusion, motor fusion, and simultaneous perception.

What is sensory fusion?

The integration of two similar images into one.

What role do vergences play in eye movements?

They change the relative angle between the visual axes.

Define motor fusion.

The maintenance of sensory fusion through varying vergence movements.

What is stereopsis?

The perception of depth from the relative disparity of images from both eyes.

What does strabismus cause?

It can cause confusion, diplopia, suppression, or abnormal correspondence.

What is suppression in relation to strabismus?

Inhibition of the image from the deviated eye to avoid double vision.

What is abnormal retinal correspondence (ARC)?

A sensory adaptation where the fovea corresponds with a non-foveal area in the deviating eye.

What occurs when an eye deviates in esotropia?

The right eye image falls on a pseudofovea causing single vision.

What is the importance of examining eye movements?

They are essential for identifying neurological issues and ensuring visual health.

What types of eye movements exist?

Duties include versions, vergences, saccades, smooth pursuits, and micro-saccades.

What are versions?

Coordinated movements of both eyes allowing gaze direction changes.

What is the function of saccades?

To rapidly place the object of interest on the fovea.

What does Hering’s Law of Equal Innervation state?

Contralateral synergists receive equal innervation for conjugate movements.

What does Sherrington’s Law of Reciprocal Innervation state?

When one muscle contracts, its direct antagonist relaxes.

Differentiate between concomitant and incomitant deviations.

Concomitant stays constant in different gaze directions; incomitant changes with gaze.

What is the function of smooth pursuits?

To maintain the image of a moving object near the fovea.

What is the latency and velocity average of a saccadic movement?

Latency of about 200 ms and average velocity of 400 degrees/sec.

What role does the cerebellum play in eye movements?

It helps generate the appropriate pursuit velocity.

What symptoms might be assessed in ocular motility testing?

The accuracy of eye movements and the magnitude of any deviation.

What is the primary difference between physiological and pathological diplopia?

Physiological is normal and often unperceived; pathological disrupts vision.

What visual axes alignment occurs during distance vision?

The visual axes are parallel.

What visual axes alignment occurs for nearer objects?

The visual axes converge.

Why is knowledge of eye movements critical?

To accurately diagnose and treat eye movement disorders.

What does 'intorsion' mean in eye movement?

Inward rotation of the eye.

What does 'extorsion' refer to in eye movements?

Outward rotation of the eye.

What does 'vergence' specifically apply to?

The horizontal meridian adjustments of the visual axes.

How is the movement in saccades characterized?

They are quick and conjugated, allowing rapid fixation on objects.

What physiological factors contribute to micro-saccades?

They help maintain perception during prolonged eye fixation.

What can happen if a deviation is found during ocular motility testing?

It can indicate a neurological problem affecting eye movements.

What role does the frontal eye field play in saccadic movements?

It maps the target image for the eyes to fixate on.