Intro to Neuro-Ophthalmology

Question 1

Describe the appropriate clinical examination steps

Answer 1

First, start by looking for anisocoria – a difference in size between pupils. Also, check for normal reaction to light and to dark. Observe the pupils in light and in dark. Then observe the papillary response to light. Also observe for segmental palsy (unequal constriction of the pupil), light-near dissociation (better constriction when viewing a near object than to light stimulation) and tonic dilation while looking at a distant target.

Question 2

Know the key features of visual field loss due to neurologic visual pathway disturbances and key clinical features of optic nerve disturbances.

Answer 2

The hallmarks of visual field defects:

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)

• If the dysfunction is unilateral, there is monocular vision loss either due to decreased acuity, field loss or both.
• There is often an afferent papillary defect (APD). (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 AP).
• Another common finding is color vision loss.
• Sometimes, the optic nerve problems can be visualized with an ophthalmascope.

Question 3

Explain steps involved in the clinical approach to complaints of diplopia

Answer 3

Ask yourself the following questions:

1. Is the diplopia binocular? If so, then the eyes are misaligned
   * If yes, then the eyes are misaligned. This could be due to Nerve III, IV, or VI palsies, the eye itself is displaced, Nueromuscular Junction problem (like myasthenia gravis) or Muscle problems
2. Is the diplopia horizontal or vertical?
   * Helps limit the number of pathways that could be involved
3. Is the diplopia worse in any specific position of gaze?
   * More localization
4. Is the diplopia worse at near or distance viewing?
   * More localization

Question 4

Sympathetic vs Parasympathetic Disturbances

Answer 4

Sympathetic innervation normally results in papillary dilation. If sympathetic pathways are damaged the abnormal pupil will be miotic and will have an abnormal dark reaction, meaning it will not fully dilate. This makes the anisocoria worse in the dark.

Parasympathetic innervation causes papillary constriction, so damage will result in a pupil that is mydriatic and poorly responsive to light. The anisocoria thus appears worse in the light.

Question 5

Horner’s Syndrome

Answer 5

Sympathetic Problem
Miosis
Abnormal dark reaction
Also accompanied by Ptosis and anhidrosis (usually unilaterally)

Question 6

Iris Damage

Answer 6

Parasympathetic Problem
Mydriasis
Abnormal light reaction
Non-neurologic cause

Question 7

3rd Nerve Palsy

Answer 7

Parasympathetic Problem
Mydriasis
Abnormal light reaction
Accompanied by other signs of 3rd nerve damage including ptosis and EOM paresis

Question 8

Tonic Pupil

Answer 8

Parasympathetic Problem
Mydriasis
Abnormal light reaction
Light-near dissociation (due to regrowth of nerve fibers, more of which are dedicated to accommodation) and segmental constriction

Question 9

Describe features of the most common cause for the complaint of oscillopsia.

Answer 9

Oscillopia is the appearance of movement in someone’s visual world due to eye movement disturbances. The most common form is nystagmus, an involuntary rhythmic osccilation. There are 2 phases in nystagmus (slow or fast) and 3 different types:

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