Exam I - Duplex Retina

bleached

When rhodopsin absorbs light it has become _______, meaning it cannot capturing any more light until the original quantum is transmitted.

Duplicity theory

theory that above a certain luminance cones mediate photopic vision and below a certain luminance rods mediate scotopic vision. Allows for smooth adaptation to varying luminance levels.

10-6 to 106 cd/m2

the range of light levels visible by the human visual system.

10

Adaptive range of the eye is how many log units?

1

Pupillary changes account for how many log units of adaptive range?

1-2

Neural responsiveness accounts for how many log units of adaptive range?

photoreceptors

The majority of the adaptive range of the eye is due to...

photoreceptor adaptation

pupil size

concentration of photopigments

neural responsiveness

four mechanisms of light adaptation of the visual system

3.4

Cones mediate pure photopic vision at luminance levels above _______ cd/m2

0.034

Rods mediate pure scotopic vision at luminance levels below ______ cd/m2

mesopic vision

Vision mediated when both rods and cones are working simultaneously. Creates a smooth transition between photopic and scotopic vision.

1.2

Pupillary response changes retinal illuminance by ______ log units

scotopic vision

Rod mediated vision occuring at luminance levels of 10−2 to 10−6 cd/m². Poor visual acuity of 20/200 and absence of color discrimination

photopic vision

cone mediated vision at luminance levels of 102 to 106 cd/m². Excellent visual acuity of 20/200 and color discrimination.

Discs

structures present in the rod and cone outer segments that contain photopigments that absorb light quanta