Test 199  (Ocular physiology)
1. The following are true:
a. a horopter is a straight line on which an object will 
    stimulate corresponding retinal points

b. objects further or nearer than the horopter to the eyes 
    are always perceived as double

c. objects in the Panum's area are perceived singly

d. objects outside the Panum's are are perceived as 

e. the Panum's area is wider centrally than peripherally


2. Doll's head phenomenon:

a. refers to movement of the eyes in a direction opposite 
    to which the head is suddenly moved

b. elicits both horizontal and vertical vestibuloocular 

c. is absent in patients with brain stem death

d. is impaired in patients with severe bilateral vestibular 

e. can not be elicited in patients with bilateral cortical 


3. The following are true about ocular circulation:
a. only 4% of the total blood supply to the eye goes to 
    the retina

b. the choroidal blood flow in normal people is ten times 
    that of the grey mater of the brain

c. autoregulation occurs in both retinal and choroidal 

d.  a PaCO2 rise of 1 mm Hg induces a 3% rise in retinal 
     blood flow

e. hypoxia causes dilatation of the retinal blood vessels

. 4. The following may explain why a patient who had had a relative
      afferent pupillary defect has normal pupillary reaction to light:
a. removal of a cataract

b. resolution of optic neuritis

c. anterior ischaemic optic neuropathy in both eyes

d. development of bilateral papilloedema

e. instillation of cyclopentolate into the affected eye

5. In efferent pupillary defect:

a. anisocoria is present

b. the damage may be in the visual cortex

c. the damage may be in the superior colliculus

d. the lesion may be in the ciliary ganglion

e. damage to the iris dilator muscle is a cause

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