Amsler Grid, EOMs, and Confrontation Visual Fields Review

Flashcards testing knowledge of entrance testing procedures including EOMs, Confrontation Visual Fields, and Amsler Grid based on the lecture material.

What three tests are typically performed in succession as preliminary entrance testing during an eye examination?

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

What is the clinical definition of versions in binocular eye movement?

Binocular movements where both eyes move in the same direction.

How are vergences defined in eye movement terminology?

Movements where both eyes move in opposite directions (for example, convergence where both eyes move inward).

What term describes monocular eye movements?

Ductions.

What directional eye movement is defined as abduction?

Movement away from the midline (away from the nose).

What directional eye movement is defined as adduction?

Movement toward the midline (toward the nose).

What are the definitions of intorsion and extorsion?

Intorsion is rotation of the eye toward the nose, and extorsion is rotation of the eye away from the nose.

Where does the Lateral Rectus (LR) muscle insert and what is its primary responsibility?

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

Where does the Medial Rectus (MR) muscle insert and what is its primary responsibility?

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

What are the insertion angle, primary action, and secondary actions of the Superior Rectus (SR) muscle?

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

What are the insertion angle, primary action, and secondary actions of the Inferior Rectus (IR) muscle?

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

Where does the Superior Oblique (SO) muscle attach and what are its primary and secondary actions?

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

Where does the Inferior Oblique (IO) muscle attach and what are its primary and secondary actions?

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

Which primary functions correspond to each of the six extraocular muscles in the right eye?

LR: Abduction, IO: Extorsion, IR: Depression, MR: Adduction, SO: Intorsion, SR: Elevation.

What general rule applies to the torsional actions of superior vs. inferior extraocular muscles?

Superiors always do intorsion, and inferiors always do extorsion.

What general rule applies to the primary and secondary actions of oblique extraocular muscles?

The primary action of obliques is always torsion, and their secondary action is abduction.

What are the two primary purposes of eye movements?

1. Move the eye so that the fovea aligns with an object of interest. 2. Hold images in place on the retina.

How are Primary Gaze and Cardinal Positions defined?

Primary Gaze is looking straight ahead. Cardinal Positions are the six positions that test the primary action of each extraocular muscle.

How are the oblique muscles vs. recti muscles isolated during extraocular movement testing?

To isolate oblique muscles, have the patient look TOWARDS the nose (adduct; 'O\'s to Nose!'). To isolate recti muscles, have the patient look AWAY from midline (abduct).

Which paired muscles are tested in Left Gaze?

Left lateral rectus and Right medial rectus.

Which paired muscles are tested in Up-Right Gaze?

Right superior rectus and Left inferior oblique.

Which paired muscles are tested in Down-Left Gaze?

Left inferior rectus and Right superior oblique.

What memory mnemonic represents the cranial nerve innervation of the extraocular muscles?

$\text{(LR6 SO4)3}$ — Lateral Rectus is innervated by the Abducens Nerve (CN VI), Superior Oblique by the Trochlear Nerve (CN IV), and all other muscles (including the lid) by the Oculomotor Nerve (CN III).

What clinical features are characteristic of an Oculomotor Nerve (CN III) palsy?

The eye is deviated downward and outward ('down and out') due to unopposed left superior oblique and lateral rectus muscles, along with ptosis (inactivation of levator palpebrae) and mydriasis (decreased tone of constrictor pupillae).

What clinical presentation occurs with a Trochlear Nerve (CN IV) lesion?

The eye is turned upward, accompanied by vertical diplopia and an inability to look down and in.

What clinical presentation occurs with an Abducens Nerve (CN VI) lesion?

The eye is turned inward (strabismus), accompanied by horizontal diplopia and an inability to look laterally.

What is Duane's retraction syndrome and in which patient group and eye is it most commonly observed?

It is a congenital condition caused by structural muscle abnormalities or innervation issues from abducens and oculomotor nuclei in the brain stem. It is most commonly noted in the left eye of females.

What characterizes Type I, Type II, and Type III Duane's retraction syndrome?

Type I: Limited Abduction; Type II: Limited Adduction; Type III: Limited Abduction and Adduction.

What common ocular features are shared across all three types of Duane's retraction syndrome?

All three types are associated with globe retraction and narrowing of the palpebral fissure with adduction, and patients typically present with esotropia in primary gaze.

What three evaluation methods are used to assess Extraocular Movements (EOMs)?

1. Single H Pattern (traditional method tracing an 'H' shape). 2. Double H Pattern (easier for beginners to differentiate movements). 3. Rotations (circular movement testing smooth pursuits).

What equipment and room setup are required when conducting EOM testing?

Equipment: Transilluminator (unoccluded, set on medium; pictured target or E on PD stick for children). Setup: Patient's glasses OFF, all room lights ON, stand light midway set to fully illuminate the target held at $40\,\text{cm}$.

How far vertically above and below the line of sight should the target be moved during EOM testing?

Approximately one head-width up ($\approx 12''$) from the line of sight (LOS), and one and a half head-widths ($18''$ to $20''$) below the LOS.

How does the examiner test for end-point nystagmus during EOM examination?

By stopping back at the line of sight (LOS) and pushing the eyes a little further out to the side ($3$ to $5''$).

What acronym is used for recording normal EOM findings and what does it stand for?

SAFE, which stands for Smooth, Accurate, Full, Extensive.

What does Hering's Law (the 'yoked muscle law') state?

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

What does Sherrington's Law state regarding extraocular muscles?

Agonist and antagonist extraocular muscles of the SAME eye are reciprocally innervated: when the agonist is excited, the antagonist is inhibited.

Which muscle pairs in the same eye are reciprocally innervated according to Sherrington's Law?

Superior Rectus & Inferior Rectus (SR & IR), Inferior Oblique & Superior Oblique (IO & SO), and Lateral Rectus & Medial Rectus (LR & MR).

What is the definition of Nystagmus and what characterizes End-point Nystagmus?

Nystagmus is an involuntary back-and-forth eye movement that disrupts fixation. End-point Nystagmus is a small, intermittent, conjugate jerk nystagmus apparent in extreme horizontal positions of gaze.

What is the difference between Positional Alcohol Nystagmus (PAN) I and PAN II?

PAN I occurs during alcohol consumption (nystagmus to the right when head is to the right, and left when head is to the left because alcohol is lighter than water). PAN II occurs during alcohol elimination (hangover phase) with nystagmus in the opposite direction due to increased specific gravity.

How is end-point nystagmus evaluated during police standardized field sobriety testing?

Police use the 'horizontal gaze nystagmus test' along $180^\circ$. If end-point nystagmus is detected within the central $30^\circ$ (shoulder to shoulder), the person has had excessive ethanol consumption.

What are the angular extents for the Humphrey 40 pt screener, Tangent Screen, Amsler Grid, Confrontation Fields, and Finger Counting Fields?

Humphrey 40 pt screener: $45^\circ$; Tangent Screen Fields: $25\text{--}30^\circ$; Amsler Grid: $5^\circ$ (central macular area); Confrontation Fields: $180^\circ$; Finger Counting Fields: $30\text{--}45^\circ$ per quadrant.

What is the setup and procedure for Finger Counting Visual Fields testing?

Patient Rx OFF, full lighting. Patient covers OS and looks at Dr's OS while Dr covers own OD. Present 1, 2, or 4 fingers midway between patient and doctor in each quadrant.

Why is 3 fingers never presented during Finger Counting Visual Fields testing?

Because 3 fingers is easily mixed up for 2 or 4, so the patient is instructed that the only options are 1, 2, or 4.

What finger presentation rules must be followed during Finger Counting Visual Fields testing?

Fingers held $15$ to $20^\circ$ out, brightly lit, pointing toward center with back of hand toward patient, not wiggled or moved, following a 'Z' pattern crossing midline 3 times.

How are normal Finger Counting Visual Fields findings recorded and what does FTFC stand for?

Recorded as 'CVF: FTFC OD, OS', where FTFC stands for Full to Finger Count.

Which visual field defects correspond to lesions at the Optic Chiasm, Right Temporal Lobe, and Right Parietal Lobe?

Optic Chiasm: Bitemporal hemianopia; Right Temporal Lobe: Left superior quadranopia; Right Parietal Lobe: Left inferior quadranopia.

What is the purpose of the Amsler Grid test and for which patient populations is it indicated?

Purpose: Assess the integrity of the visual field corresponding to the macular region ($5^\circ$). Indications: Patients older than mid-50s, diabetics, patients with macular conditions, or patients taking potentially toxic medications.

What is the standard structure and function of the Amsler Grid?

It is a grid chart with a central fixation dot used to track changes in vision and screen for macular field defects such as scotomas or metamorphopsia.

What are the clinical uses for a Red grid on black chart vs. a White grid on black with fixation 'X' chart?

Red grid on black is used to detect early drug toxicity. White grid on black with fixation 'X' is used when a patient has central suppression or scotoma.

What testing distance and instructions must be used when administering the Amsler Grid test?

Held at $30\,\text{cm}$ (the only near preliminary test NOT done at $40\,\text{cm}$) with full lighting and best near correction worn. The patient covers OS first, fixates on the center white dot, and is asked if all 4 corners are visible, if all lines are straight, and if all small squares are uniform.