Vision and Aging

Question 1

what are the changes in the cornea due to aging

Answer 1

1. changes shape (usually increase in against the rule astig)
2. losses in clarity (resulting in increased scatter)

Question 2

how does the pupil change with age

Answer 2

diameter decreases w/ age => senile miosis
-decreased pupil diamter means reduced retinal illuminance (T=AxL)
Trolands=pupil area x luminance (cd/m^2)

Question 3

by the age of 80 how large is the pupil

Answer 3

2-3mm

Question 4

what are teh advantages of senile miosis

Answer 4

1. reduced aberrations (less peripheral aberratoins)
2. increased depth of focus

these 2 advantages help maintian object sharpenss

Question 5

what are the changes in the lens

Answer 5

1. optical density increases

2. thickness and rigidity increases

Question 6

whatundrgoes the most significant age-related changes

Answer 6

lens

Question 7

the increase in lens optical density results in what?

-for what kind of wavelenth

Answer 7

reduced retinal illumination

for short wavelength lights

Question 8

the increase in lens size and it becoming harder leads to waht

Answer 8

presby

Question 9

the retinal illuminace at age 60 is 1/3 of the ret ill at the age of 20 bc of
what does this affect

Answer 9

increased opitcal density of lens and senile miosis

-reduction affects contrast sensitivity, VA, dark adaptation etc

Question 10

what happens to the vit

Answer 10

collagen fibers of vit deteriroate

=>floaters

Question 11

floaters increase what

waht does this result in

Answer 11

intra-ocular glare

results in contrast decrease

Question 12

what happens to the retina

Answer 12

reduction in # of rods and cones
rod count decreases faster than cone count
-photopigment density decreases as well
-photoreceptor transduction decreases
-RPE reduces in number => less melanin molec, incrased intraocular glare => phagocytosis compromised

Question 13

by the age of 60 there is a ___% dcrease in ganglion cells

Answer 13

30%

Question 14

the decrease in thickness of layer 1 in V1 suggests waht

Answer 14

neuronal loss at the primary visual cortex

Question 15

do the elderly experience more diffiuclty dark or light adaptation

Answer 15

dark adaptation: in a dark adapatation curve the rate of dark adapatation decreaes and the abs threshold increases w/ age

Question 16

what may the cone and rod threshold increase be due to

Answer 16

cone and rod loss throughout adulthood

Question 17

the slower rate of dark adaptation might be due to..

Answer 17

the slowing of rhodopsin regeneration in aging retina

-in turn this might be due to the aging RPE and the thickening of bruch’s

Question 18

if senile miosis and less aborption are not taken into consideration in such experiemets, why might they produce similar effects on thresholds

Answer 18

due to reduced retinal ill

Question 19

by the age of 80, VA is

Answer 19

~20/40

-~1 line per decade after age 60

Question 20

what makes it difficult to correlate the decrease in VA in decrased cone dnsity

Answer 20

the large inter-observer variability in foveal cone density w/ comparable VA

Question 21

what makes it difficult to connect the decrease in VA in decreased cone density

Answer 21

the large inter-observer variability in foveal cone desnity

Question 22

a change in contrast sensitivity function should be expected bc….

Answer 22

VA is a data point on the CSF

Question 23

the peak sensitivity shifts to lower spatial frequ of what

Answer 23

~4c/deg to ~2c/deg

-reduction in contrast sensitivity for int and high spatial frequ

Question 24

the loss in high spatial frq can be attricuted to…

Answer 24

optical factors (reduced retinal ill and scattering) and neural factors 
-an impairment in the parvocellular pathway is most likely the neural cause of decreased contrast sens

Question 25

why can we not predict the sensitivity at low spatial freq when we know VA

Answer 25

little correlation btwn sensitivities on high and low spatial freq

Question 26

why do events that appear as separate to young observers might not be perceived as separate for older
-reduction in CFF

Answer 26

reduced retinal illuminace

ferry-porter law

Question 27

CFF is a data point in the ____ and therefore a reduction in temporal sensitivity is expected

Answer 27

temporal modulation transfer function (TMTF)

Question 28

temporal sensitivity is reduced at ___ and ____ temporal freq

Answer 28

high and intermeidate

Question 29

the range of affected temporal freq points towards a deficit in…

Answer 29

magnocellular pathway

Question 30

what did ball and sekuler use to study motion perception in the elderly

Answer 30

random dot kinetograms

Question 31

what did ball and sekuler find

Answer 31

older observers were less accurate on judging the direction of motion (3-fold diff)
-motion perception deficit cant be explained by optical factors but it must rather hav e neural basis