Neurophthalmology 2

Question 1

The hallmarks of visual field defects:

Answer 1

1. The defect respects vertical and horizontal meridian (optic nerve and beyond)
2. Homonymous field loss (optic tract and beyond)
3. The defect is a combination of a homonymous field loss plus respect of the vertical meridian (optic tract and beyond)

exception is optic n defects do not always respect meridian

Question 2

If optic n dysfunction is unilateral:

Answer 2

1. monocular vision loss either due to decreased acuity, field loss or both.
2. afferent papillary defect (APD)
3. color vision loss
4. The Lateral Geniculate nucleus sees relatively less light than the other side and dilates.

Question 3

APDs occur when:

Answer 3

there is dysfunction prior to the synapse of the retinal ganglion in the thalamus

Question 4

APD is tested

Answer 4

by the swinging flashlight test:
if the light is shined at one side and both pupils constrict, then the light is shined in the other eye and it dilates, there is a APD.

Question 5

here are 4 questions that need to be addressed in a diplopia evaluation:

Answer 5

1. Is the diplopia binocular?
2. Is the diplopia horizontal or vertical?
3. Is the diplopia worse in any specific position of gaze?
4. Is the diplopia worse at near or distance viewing?

Question 6

Is the diplopia binocular?

Answer 6

If yes, then the eyes are misaligned.

Question 7

cause of misaligned eyes

Answer 7

This could be due to the NEJM of causes –

1. Nerve (3rd, 4th or 6th palsies)
2. Eye (displaced)
3. Juntion Neuromuscular (myasthenia gravis)
4. Muscle (thyroid or rare myopathies)

Question 8

Is the diplopia horizontal or vertical?

Answer 8

helps limit number of pathways involved

Question 9

Is the diplopia worse in any specific position of gaze?

Answer 9

localization

Question 10

Is the diplopia worse at near or distance viewing?

Answer 10

localization

Question 11

Oscillopia is the

Answer 11

appearance of movement in someone’s visual world due to eye movement disturbances.

The most common form is nystagmus, an involuntary rhythmic osccilation.

Question 12

2 phases in nystagmus

Answer 12

1. slow

2. fast

Question 13

3 types of oscillopia

Answer 13

1. Pendular (slow – slow)
2. Jerk (fast – slow)
3. Mixed (slow – slow and fast – slow)

Question 14

Nystagmus can be

Answer 14

1. horizontal
2. vertical
3. torsional
4. mixed

Question 15

Nystagmus is localized to the _____.

Answer 15

8th nerve or the CNS.

Question 16

Downbeat nystagmus is localized to the ____

Answer 16

cervical-medually junction causes bouncing of the eye up and down.

Question 17

Downbeat nystagmus is caused by:

Answer 17

disease of the cerebellar flocculus such as MS, Chiari malformations or tumors.

Question 18

The flocculus normally inhibits the:

Answer 18

anterior semicircular canals connections, which causes the eyes to drift upwards and require a rapid downward correction.

Question 19

anterior semicircular canals connections stimulate the eyes to ____

Answer 19

move up