Ocular Motility/ Binocular Vision

Question 1

What is forced duction testing used for?

Answer 1

Differentiating between muscle weakness and restrictive causes of limitations in extraocular muscle movements

This test helps identify whether the issue is due to muscle paresis or restriction/entrapment.

Question 2

What type of anesthesia is typically used during forced duction testing?

Answer 2

Topical eye drops

This method is used to minimize discomfort for the patient during the procedure.

Question 3

What is the initial instruction given to the patient during forced duction testing?

Answer 3

Look as far as possible in the direction of the suspected underacting muscle

This action recruits maximum innervation to the muscle being tested.

Question 4

What tool does the examiner use to perform forced duction testing?

Answer 4

Forceps

The forceps are used to grasp the conjunctiva near the limbus.

Question 5

What indicates muscle paresis during forced duction testing?

Answer 5

If the forceps can rotate the globe further than the patient can move it on his own

This suggests some degree of muscle weakness.

Question 6

What indicates restriction or entrapment of the muscle during forced duction testing?

Answer 6

If the globe cannot be rotated farther than the patient’s movement

This implies that the muscle is likely restricted or entrapped.

Question 7

In a scenario where the patient has a deficit in superior gaze, which muscle should be anesthetized?

Answer 7

Inferior rectus muscle

This muscle is involved when testing for deficits in upward gaze.

Question 8

What is considered a positive forced duction test?

Answer 8

Resistance during further superior rotation of the eye

This indicates potential muscle paresis.

Question 9

What is considered a negative forced duction test?

Answer 9

Effortless rotation of the eye

This suggests that there is no muscle paresis present.

Question 10

What is the Worth-4-dot test?

Answer 10

A visual test used to assess binocular vision and perception of color.

It involves projecting four dots onto a screen to evaluate how each eye perceives them.

Question 11

What colors are typically used in the Worth-4-dot test?

Answer 11

Red, green, and white

The top circle is usually white, the bottom circle is red, and the two horizontal circles are green.

Question 12

What does the presence of three green circles viewed to the right of two red circles indicate?

Answer 12

Crossed diplopia (exo deviation)

This suggests a misalignment in the eyes where the images appear crossed.

Question 13

What does the perception of three green circles viewed to the left of two red circles indicate?

Answer 13

Uncrossed diplopia (eso deviation)

This indicates a different type of misalignment where images appear uncrossed.

Question 14

What does viewing three green circles alone signify?

Answer 14

Right eye suppression

This suggests that the right eye is not contributing to the visual perception.

Question 15

What does a patient reporting two red circles indicate?

Answer 15

Suppression of the left eye

This indicates that the left eye is not being utilized in visual perception.

Question 16

In the Worth-4-dot test, what color does the right eye perceive for the top circle if the patient has simultaneous perception?

Answer 16

Pink/red

The right eye views the top circle as a mix of red and the white light.

Question 17

What should both eyes combined view in the Worth-4-dot test under normal conditions?

Answer 17

Four circles: two green, one red, and one red/green

This is the expected outcome if both eyes are functioning properly.

Question 18

What is the purpose of dissociating methods in ophthalmology?

Answer 18

To cause diplopia with prism, enabling the clinician to quantify a phoria.

Phoria refers to a latent deviation of the eyes that is not present when both eyes are open.

Question 19

What is the Von Graefe method?

Answer 19

A dissociating technique involving placing a 4 base-up dissociating prism before the left eye and a biasing prism before the right eye.

This method helps to quantify phoria by aligning two perceived targets.

Question 20

What should the patient initially perceive when using the Von Graefe method?

Answer 20

Two targets, one up and to the right, and the other down and to the left.

This initial perception is crucial for assessing the alignment of the eyes.

Question 21

What is recorded when the targets are aligned horizontally in the Von Graefe method?

Answer 21

The amount of prism before the left eye.

This amount indicates the degree of phoria present.

Question 22

How is a deviation described when there is base-up prism in front of the left eye?

Answer 22

As either right hyperphoria or left hypophoria in the amount equal to the neutralizing prism before the left eye.

Hyperphoria indicates an upward deviation, while hypophoria indicates a downward deviation.

Question 23

What do distortion methods do in the context of ophthalmology?

Answer 23

Blur one or both retinal images to eliminate the reflex for binocular fusion.

This helps in assessing the alignment of the eyes by disrupting normal visual perception.

Question 24

What is the Modified Thorington method?

Answer 24

A technique that utilizes a Maddox rod to create distortion.

This method aids in determining the presence and degree of strabismus.

Question 25

What does the Hirschberg test assess?

Answer 25

The position of the corneal reflexes relative to the center of the pupil to determine the presence or absence of heterotropia.

Heterotropia refers to a constant misalignment of the eyes.

Question 26

What does temporal displacement of the corneal reflex suggest?

Answer 26

Esotropia.

Esotropia is a condition where one or both eyes turn inward.

Question 27

What does nasal displacement of the corneal reflex infer?

Answer 27

Exotropia.

Exotropia is characterized by one or both eyes turning outward.

Question 28

What is the purpose of the Bruckner reflex test?

Answer 28

To denote an asymmetry between the brightness of the retinal reflexes, indicating possible strabismus or other pathologies.

This test helps in diagnosing conditions like anisometropia or retinoblastoma.

Question 29

In the event of strabismus, how does the deviated eye appear in the Bruckner reflex test?

Answer 29

Brighter, because more light is reflected from the retinal periphery.

This brightness difference is key to identifying strabismus.