ABO Neuro-Ophthalmology and Orbit 2 — Questions and Answers
Question 1: In the Optic Neuritis Treatment Trial, what was the main effect of IV methylprednisolone followed by oral prednisone compared with placebo?
- Lower long-term risk of multiple sclerosis at 10 years
- Better final visual acuity at 1 year
- No difference in speed or extent of recovery
- Faster visual recovery without better long-term visual outcome (Correct answer)
Correct answer: Faster visual recovery without better long-term visual outcome
IV steroids sped up recovery but did not change final visual acuity, and the lower MS risk they showed did not last past about 2-3 years.
Question 2: Which ONTT treatment arm was associated with an increased rate of recurrent optic neuritis?
- Observation with vitamin supplementation
- Placebo
- Oral prednisone alone at standard dose (Correct answer)
- IV methylprednisolone followed by oral taper
Correct answer: Oral prednisone alone at standard dose
Oral prednisone alone (1 mg/kg/day) increased the risk of new optic neuritis attacks, so it is avoided as monotherapy.
Question 3: A patient has a large pupil with segmental iris sphincter palsy, light-near dissociation, and tonic redilation. Which agent best confirms the diagnosis?
- Apraclonidine 0.5%
- Hydroxyamphetamine 1%
- Cocaine 10%
- Dilute pilocarpine 0.1% (Correct answer)
Correct answer: Dilute pilocarpine 0.1%
A tonic (Adie) pupil shows cholinergic denervation supersensitivity and constricts to dilute pilocarpine.
Question 4: In a patient with confirmed Horner syndrome, hydroxyamphetamine 1% fails to dilate the affected pupil. Where is the lesion?
- First-order (central) neuron
- Second-order (preganglionic) neuron
- Third-order (postganglionic) neuron (Correct answer)
- Oculomotor nerve
Correct answer: Third-order (postganglionic) neuron
Hydroxyamphetamine releases norepinephrine from intact postganglionic terminals, so failure to dilate indicates a third-order lesion.
Question 5: Why does apraclonidine 0.5% reverse the anisocoria in Horner syndrome?
- Blockade of norepinephrine reuptake
- Direct stimulation of the iris sphincter
- Release of stored norepinephrine from terminals
- Denervation supersensitivity of alpha-1 receptors in the iris dilator (Correct answer)
Correct answer: Denervation supersensitivity of alpha-1 receptors in the iris dilator
Apraclonidine's weak alpha-1 activity dilates the supersensitive denervated pupil, which reverses the anisocoria.
Question 6: A patient cannot adduct the left eye on right gaze, has abducting nystagmus of the right eye, and convergence is preserved. Where is the lesion?
- Right medial longitudinal fasciculus
- Right paramedian pontine reticular formation
- Left abducens nucleus
- Left medial longitudinal fasciculus (Correct answer)
Correct answer: Left medial longitudinal fasciculus
An internuclear ophthalmoplegia is named for the side of the adduction deficit, which matches the side of the MLF lesion.
Question 7: In one-and-a-half syndrome, which horizontal eye movement remains intact?
- Abduction of the ipsilateral eye
- Adduction of the ipsilateral eye
- Abduction of the contralateral eye (Correct answer)
- Adduction of the contralateral eye
Correct answer: Abduction of the contralateral eye
A lesion of the abducens nucleus/PPRF plus the ipsilateral MLF leaves only contralateral-eye abduction.
ABO Neuro-Ophthalmology and Orbit 2
In the Optic Neuritis Treatment Trial, what was the main effect of IV methylprednisolone followed by oral prednisone compared with placebo?