Test 12

1. Unilateral miosis occurs in: a. pituitary disease b. syringomyelia c. Wallenberg's syndrome d. internal cord artery aneurysm e. nasopharyngeal carcinoma answera.F   b.T   c.T   d.T   e.T Unilateral miosis occurs with lesion to the  sympathetic nervous system. All conditions above cause lesion to the sympathetic innervation of the pupil except for pituitary lesion.     2. Horner's pupil: a. reacts to light normally b. does not react to accommodation c. causes problems with accommodation d. constricts with pilocarpine e. dilate with atropine answera.T   b.F   c.F   d.T   e.T Apart from miosis, the pupil reacts normally to light and accommodation. The pupil also reacts to pilocarpine and atropine because they act directly on the receptors.   3. Unilateral lateral mydriasis occurs in: a. uncal herniation b. unilateral carotid artery disease c. Urrets-Zavalia syndrome d. intravitreal iron foreign body e. acute angle closure glaucoma answera.T   b.T   c.T   d.T   e.T Uncal herniation causes compression of the third nerve. Carotid artery disease and acute angle  closure glaucoma causes iris ischaemia and hence pupil dilatation. Urrets-Zavalia's syndrome occurs after corneal  grafting for keratoconus and is believed to be caused by ischaemia. Iron foreign body causes ocular siderosis.     4. Light near dissociation occurs in: a. myotonic dystrophy. b. Argyll-Robertson's pupil c. Parinaud dorsal midbrain syndrome. d. aberrant regeneration of the third nerve e. familial amyloidosis answera.T   b.T   c.T  d.T   e.T Light-near dissociation also occurs in: diabetes mellitus chronic alcoholism Adie's pupil.   5. Dilated pupil that can not be constricted with pilocarpine include: a. third nerve palsy b. Adie's pupil c. pupil dilated with atropine d. pupil dilated with phenylephrine e. ocular siderosis. answera.F   b.F   c.T   d.F   e.T Pilocarpine acts directly on the constrictor muscles of the pupil. Atropine is a non-competitive blockers and therefore  the pupil can not be constricted with pilocarpine. Phenylephrine acts on the dilator muscle leaving the constrictor muscles for the pilocarpine to act on. Ocular siderosis causes damage to the iris muscle.   Return to the main page