Glaucoma and Visually Evoked Potentials (M2)

Question 1

What is glutamate excitotoxicity thought to be responsible for?

Answer 1

1. acute ischemic pathologies such as stroke in the CNS

2. some chronic neurodegenerative disorders

Question 2

What are thought to be the first cells affected by glaucoma? 1. So which pathway did functional tests target? 2

Answer 2

1. parasol RGCs (larger RGCs)

2. magno pathway

Question 3

What is the RGC death theory that suggests RGC axons pinched at the lamina cribosa, disrupting axoplasmic flow?

Answer 3

neurotrophin deprival hypothesis

Question 4

What does ischemic anterior optic neuropathy result in?

Answer 4

optic nerve pallor but NOT optic nerve cupping

Question 5

If a disease primarily affects the magno pathway, what does the patient have a decreased sensitivity to?

Answer 5

1. low spatial frequencies

2. high temporal frequencies

Question 6

What are FDT perimetry testing capable of catching?

Answer 6

some early damage to moderate glaucoma

Question 7

What happens to the lamina cribosa during POAG?

Answer 7

1. thinner laminar beams

2. bigger pored superiorly and inferiorly

Question 8

What is the most important risk factor for primary open-angle glaucoma?

Answer 8

IOP

Question 9

What can VEP be used for?

Answer 9

1. measure of VA and contrast sensitivity in patients with communication difficulties
2. helpful in cases of malingering

Question 10

About what percentage of RGCs had to die in order for visual field defects to be detectable?

Answer 10

50%

Question 11

Where is the initial damage to RGC axons during POAG?

Answer 11

lamina cribosa

Question 12

What are the retinal neurons that are affected in glaucoma?

Answer 12

retinal ganglion cells (RGCs) only

Question 13

What is most of the electrical activity detected using VEPs due to?

Answer 13

the fovea

Question 14

What is the idea that there should be tests that use specific stimuli that target distinct populations of RGCs (target magno vs. parvo vs. konio)?

Answer 14

multi-channel theory

Question 15

What is the idea that as retinal ganglion cells die ,they are capable of releasing signals that can cause adjacent RGCs to die? 1. What does this hypothesis help to explain? 2. What are the therapeutic types that are designed to prevent this? 3

Answer 15

1. secondary degeneration
2. continued progression of RGC death once IOP has been lowered
3. neuroprotection

Question 16

At what wavelength is there a greater sensitivity to color versus flicker?

Answer 16

less than 475nm

Question 17

What can measure the small waves of activity generated in the occipital lobe when the eyes are stimulated with complex stimuli?

Answer 17

visually evoked potentials electrodes

Question 18

What does neurotrophin deprivation in RGCs cause the cell to do?

Answer 18

program apoptosis

Question 19

What is the idea that the decreasing blood supply to the optic nerve results in RGC death called?

Answer 19

vascular compromise

Question 20

What is the most commonly attempted method to obtain neuroprotection? 1. Why? 2

Answer 20

1. blocking glutamate receptors

2. most common excitatory neuron in the retina and involved in the vertical pathway

Question 21

What does the activation of glutamate receptors cause for cells? 1. When is this a problem? 2

Answer 21

1. calcium ions enter into neurons through channels

2. too much calcium triggers apoptosis

Question 22

Why is SWAP successful at catching glaucoma earlier if it targets the konio pathway?

Answer 22

redundancy in the visual system when a pretty non-specific stimulus is used

Question 23

What is the rank of glaucoma in terms of leading causes of blindness in the world? 1. America? 2

Answer 23

1. second (glaucoma #1)

2. second (ARMD #1)

Question 24

What tests are decreased with open-angle glaucoma?

Answer 24

CFF’s decreased

Question 25

What is the test that has grating alternating at over 25 Hz which causes an illusion in which you see double the actual gratings? 1. What is varied in the test? 2

Answer 25

1. FDT perimetry (frequency doubling)

2. contrast varied and threshold of detection determined

Question 26

At what wavelength is there a greater sensitivity to flicker versus color?

Answer 26

between 575 and 600nm