Amsler Grid, Extraocular Movements (EOMs), and Confrontation Visual Fields (CVF)

Comprehensive practice flashcards covering Amsler Grid testing, Extraocular Movements (EOMs), and Confrontation Visual Fields (CVF) based on clinical lecture notes.

What entrance tests are generally performed on all patients at each exam in addition to visual acuity?

Amsler Grid, Extraocular Movements (EOMs), and Confrontation Visual Fields (CVF).

What are Extraocular Muscles (EOMs)?

The six muscles that control eye movements.

What are versions?

Binocular eye movements in which both eyes move in the same direction.

What are vergences?

Eye movements in which both eyes move in opposite directions, such as convergence.

What are ductions?

Monocular eye movements.

What is abduction?

Movement of the eye away from the midline or away from the nose.

What is adduction?

Movement of the eye toward the midline or toward the nose.

What is elevation?

Upward movement of the eye.

What is depression?

Downward movement of the eye.

What is intorsion?

Rotation of the eye toward the nose.

What is extorsion?

Rotation of the eye away from the nose.

Where does the lateral rectus insert and what is its action?

It inserts on the lateral side of the eye and is responsible for abduction.

Where does the medial rectus insert and what is its action?

It inserts on the medial side of the eye and is responsible for adduction.

Where does the superior rectus insert and what are its actions?

It inserts on the top of the eye at $23^\circ$ to the line of sight; primary action is elevation, secondary actions are intorsion and adduction.

Where does the inferior rectus insert and what are its actions?

It inserts on the bottom of the eye at $23^\circ$ temporal to the line of sight; primary action is depression, secondary actions are extorsion and adduction.

Where does the superior oblique attach and what are its actions?

It attaches to the upper temporal region of the eye at a $54^\circ$ angle medial to the line of sight; primary action is intorsion, secondary actions are depression and abduction.

Where does the inferior oblique attach and what are its actions?

It attaches to the lower temporal region of the eye at a $51^\circ$ angle medial to the line of sight; primary action is extorsion, secondary actions are elevation and abduction.

What do all superior muscles have in common?

They always perform intorsion.

What do all inferior muscles have in common?

They always perform extorsion.

What is the primary action of the obliques?

Torsion.

What is the secondary action of the obliques?

Abduction.

What are the two primary purposes of eye movements?

To align the fovea with an object of interest and to hold images in place on the retina.

What is primary gaze?

Looking straight ahead.

What are the cardinal positions of gaze?

Six positions used to test the primary actions of the extraocular muscles.

How many extraocular muscles are present in each eye?

Six.

According to normal innervation, how should the two eyes be stimulated?

Each eye should receive the same amount of innervation as the other eye.

How do opposing muscles within the same eye coordinate?

Each muscle should receive equal relaxation signals as its opposing muscle receives contraction signals.

What is the primary function of the lateral rectus?

Abduction.

What is the primary function of the medial rectus?

Adduction.

What is the primary function of the superior rectus?

Elevation.

What is the primary function of the inferior rectus?

Depression.

What is the primary function of the superior oblique?

Intorsion.

What is the primary function of the inferior oblique?

Extorsion.

How are oblique muscles isolated during cardinal position testing?

By having the patient adduct the eye and look toward the nose. Remember: "O's to Nose."

How are rectus muscles isolated during cardinal position testing?

By having the patient abduct the eye and look away from the midline.

Which muscles are tested in right gaze?

Right lateral rectus and left medial rectus.

Which muscles are tested in left gaze?

Left lateral rectus and right medial rectus.

Which muscles are tested in up-right gaze?

Right superior rectus and left inferior oblique.

Which muscles are tested in up-left gaze?

Left superior rectus and right inferior oblique.

Which muscles are tested in down-right gaze?

Right inferior rectus and left superior oblique.

Which muscles are tested in down-left gaze?

Left inferior rectus and right superior oblique.

From whose perspective is the H test written and shown?

The patient's point of view.

Which cranial nerve innervates the lateral rectus?

The Abducens nerve (CN VI).

Which cranial nerve innervates the superior oblique?

The Trochlear nerve (CN IV).

Which cranial nerve innervates all other extraocular muscles and the lid?

The Oculomotor nerve (CN III).

What mnemonic is used to remember EOM innervation?

LR6 SO4, all others CN3.

What are the signs of an oculomotor nerve (CN III) lesion?

Eye deviated downward and outward, ptosis, and loss of pupillary reflexes.

What are the signs of a trochlear nerve (CN IV) lesion?

Eye turned upward, vertical diplopia, and inability to look down and in.

What are the signs of an abducens nerve (CN VI) lesion?

Eye turned inward (strabismus), horizontal diplopia, and inability to look laterally.

What is Duane retraction syndrome?

A congenital condition involving structural muscle abnormalities or innervation issues involving the abducens and oculomotor nuclei.

Which eye and population are most commonly affected by Duane retraction syndrome?

The left eye of females.

What is Type I Duane retraction syndrome?

Limited abduction.

What is Type II Duane retraction syndrome?

Limited adduction.

What is Type III Duane retraction syndrome?

Limited abduction and adduction.

What findings are common to all types of Duane retraction syndrome?

Globe retraction and narrowing of the palpebral fissure on adduction.

How do patients with Duane retraction syndrome typically present in primary gaze?

With esotropia.

What is the purpose of EOM testing?

To assess the patient's ability to perform conjugate eye movements.

What are the three EOM evaluation techniques?

Single H pattern, Double H pattern, and rotations.

What equipment is commonly used for EOM testing?

A transilluminator.

How should the patient be positioned for EOM testing?

Glasses off, lights on, and a target held $40\,\text{cm}$ from the patient.

What type of target should be used for EOM testing?

A small-to-medium target, large enough to follow accurately; picture targets may be used for children.

What is the first instruction given to patients during EOM testing?

Follow the target with the eyes only and do not move the head.

Where should EOM testing begin?

At primary position directly in front of the patient.

Why might the examiner need to hold the eyelids during EOM testing?

To observe the eyes in downgaze.

What should be evaluated during EOM testing?

Smoothness, range, accuracy, pursuit ability, presence of pain, diplopia, restrictions, lagging, jerky movements, and end-point nystagmus.

What is a normal EOM notation?

"EOMs: Smooth & Full, No pain or diplopia" or "EOMs: SAFE (Smooth, Accurate, Full, Extensive)."

What does SAFE stand for in EOM documentation?

Smooth, Accurate, Full, Extensive.

What is Hering's Law?

For movements of both eyes in the same direction, corresponding muscles receive equal innervation.

What is an example of Hering's Law?

Looking right requires equal innervation to the right lateral rectus and left medial rectus.

What happens in a paretic muscle according to Hering's Law?

Extra innervation is required and the yoked muscle in the fellow eye receives the same extra innervation.

What is Sherrington's Law?

Agonist and antagonist EOMs in the same eye are reciprocally innervated; when the agonist is excited, the antagonist is inhibited.

Which EOM pairs are antagonists according to Sherrington's Law?

SR & IR, IO & SO, and LR & MR.

What is nystagmus?

An involuntary back-and-forth movement of one or both eyes that disrupts fixation.

What directions can nystagmus occur in?

Horizontal, vertical, or torsional.

What is end-point nystagmus?

A small, intermittent, conjugate jerk nystagmus seen most often in extreme horizontal gaze.

When is end-point nystagmus more noticeable?

In extreme horizontal gaze and when the patient is tired.

What is positional alcohol nystagmus (PAN)?

Nystagmus that occurs during alcohol consumption when the head is placed sideways.

What characterizes PAN I?

Nystagmus to the right with right head tilt and to the left with left head tilt.

What characterizes PAN II?

Nystagmus in the opposite direction, usually appearing later during alcohol elimination.

What causes positional alcohol nystagmus?

Changes in the specific gravity of extracellular fluids within the semicircular canals caused by alcohol.

Why does PAN I occur?

Alcohol is lighter than water, making the semicircular canals more responsive to gravity.

Why does PAN II occur?

During alcohol elimination, specific gravity increases as alcohol leaves the body, contributing to hangover symptoms.

How is end-point nystagmus used in sobriety testing?

It is evaluated during the horizontal gaze nystagmus test used by police.

What finding suggests excessive ethanol consumption during horizontal gaze nystagmus testing?

End-point nystagmus occurring within the central $30^\circ$ of gaze.

What are the types of screening visual field tests and their approximate field coverage?

Humphrey 40-point screener $45^\circ$, Humphrey FDT $30^\circ$, Tangent Screen $25-30^\circ$, Amsler Grid $5^\circ$, Confrontation Fields $180^\circ$, Finger Counting Fields $30-45^\circ$ in quadrants.

What is the purpose of screening visual field testing?

To screen for unnoted visual field defects, especially large or substantial losses.

Can most screening visual field tests detect early disease-related loss?

No, most cannot detect early visual field loss.

What equipment is needed for screening visual fields?

An overhead lamp and an occluder.

How is finger-counting visual field testing set up?

Rx off, full lighting, patient covers one eye while examiner covers the corresponding eye.

Where are the fingers presented during finger-counting visual fields?

Midway between the patient and examiner in each visual field quadrant.

What finger numbers are used during finger-counting visual fields?

1, 2, or 4 fingers only.

Why is three fingers not used in finger-counting visual fields?

Because it is easily confused with two or four fingers.

What are the rules for finger-counting visual field testing?

Keep fingers $15-20^\circ$ from fixation, brightly lit, use different numbers in each quadrant, point toward center, do not wiggle fingers, and use a Z-pattern crossing the midline three times.

How are normal finger-counting visual fields recorded?

CVF: FTFC OD, OS.

What does FTFC stand for?

Full To Finger Count.

Why should OD and OS be recorded separately for CVF results?

Because OU would indicate both eyes were open together.

How should abnormal CVF findings be documented?

Record as restricted and specify the location.

What is the purpose of the Amsler Grid?

To assess the integrity of the visual field corresponding to the macular region of the retina.

When is Amsler Grid testing indicated?

For patients older than the mid-50s, diabetics, patients with macular conditions, or patients taking potentially toxic medications.

What is the standard Amsler Grid chart?

A white grid on a black background.