Test 161  (Ocular physiology )
1. The following are true about the sensitivity of the visual system:
a. in the dark the peak sensitivity of the eye is around 

b. in the light the peak sensitivity of the eye is around

c. the cone can not respond to white flickering light of 
    20 Hz and above

d. a dark-adapted eye is more sensitive to blue-green 
    light than a light-adapted eye

e. photopic ERG has a larger value than scotopic ERG 


2. Purkinje's shift:
a. refers to the transition of retinal sensitivity between 
    photopic and scotopic vision

b. refers to the shift in the spectral sensitivity of the human
    retina toward shorter wavelengths of light

c. accounts for blue colour appearing brighter at dusk

d. accounts for red colour appearing brighter at dawn

e. is absent in rod monochromat

3. In a patient with dense cataract and poor retina view, the
    following tests can be used to test the macular function:
a. relative afferent pupillary defect

b. laser interferometry

c. Haidinger brushes

d. Visual evoked potential

e. pattern ERG


4. The release of acetylcholine is blocked by:

a. hemicholinum

b. venom of black widow spider

c. cocaine

d. botulinum toxins 

e. vesamicol


5. The following are true:
a. Kirschman's law: the greatest contrast in colour is 
    seen when the luminosity differnece is small

b. Emmbert's law: the perceived size of an object varies 
    in proportion to the distance of the surface on which it 
    is projected

c. Hering's law: the contraction of a muscle is 
    accompanied by simultaneous and proportional 
    relaxation of the antagonist

d. Troxler's phenomenon: an image in the periphery of the 
     retina tends to fade or disappear during steady fixation 
     of another object

e. Aubert's phenomenon: in the dark, when the head is 
    tilted slowly while looking at a bright vertical line, the 
    line will tilt in the opposite direction

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