Lecture 12 (Ocular Toxicology)

Question 1

structure of retina

Answer 1

consists of macula and fovea

cell types w/in retina:
- photoreceptors
- horizontal, bipolar, amacrine cells
- inner synaptic layer
- ganglion cells

Question 2

optic nerve made of…

Answer 2

retinal ganglion cells

Question 3

parts of the brain reached by retinal ganglion cells

Answer 3

suprachiasmatic nucleus

medial temporal lobe

lateral geniculate nucleus

stratum cellulare

Question 4

why is retina part of the brain?

Answer 4

because developmental origin is in the forebrain

Question 5

what are photoreceptors and what do they do

Answer 5

rods – night

cones – daytime, color

Question 6

diseases affecting photoreceptors

Answer 6

retina pigmentosa

macular degeneration

Question 7

symptoms of retina pigmentosa

Answer 7

loss of night vision
loss of side (peripheral) vision

sensitivity to bright light
loss of color vision

Question 8

retinal ganglion cell (optic nerve) diseases

Answer 8

glaucoma
retina neuropathy
optic neuritis

Question 9

what is retina neuropathy?

Answer 9

loss of nerve cells in retina

Question 10

toxicants that affect photoreceptors

Answer 10

methyl mercury

lead

toluene

Question 11

toxicants that affect bipolar cells

Answer 11

prenatal lead

Question 12

toxicants that affect retinal ganglion cells

Answer 12

lead

pesticides

cyandie

Question 13

toxicants that affect amacrine cells

Answer 13

prenatal lead

Question 14

what epidemic happened in Cuba?

Answer 14

optic and peripheral neuropathy

Question 15

what were the symptoms of optic and peripheral neuropathy epidemic?

Answer 15

blurry vision

loss of color vision

scotoma (blind spot)

blindness

peripheral neuropathy (damage to nerves outside brain and spinal cord)

Question 16

neuropathy symptoms in men vs. women in cuba

Answer 16

optic neuropathy:
- men had much higher than women

peripheral neuropathy:
- women had slightly higher than men

Question 17

likely cause of optic neuropathy epidemic in cuba

Answer 17

diet –> Vitamin-B deficiency

cyanide poisoning

increased physical activity –> drained B-vitamins

Vitamin B counteracts cyanide from disrupting cytochrome oxidase in Complex IV

if cyanide disrupts Compelx IV –> no nutrient and oxygen supply –> nerve tissue is damaged and lost –> vision loss

Question 18

how does moonshine cause blindness?

Answer 18

corn fermentation –> methanol

methanol –> formic acid –> disrupts cytochrome oxidase in Complex IV –> oxygen and nutrient lost –> nerve tissue is damaged and lost –> vision loss

Question 19

how does formic acid affect vision?

Answer 19

formic acid accumulates in the vitreous and disrupts retinal ganglion cells

Question 20

which cell types are most susceptible to dysfunction and cell death?

Answer 20

retinal ganglion cells

photoreceptors

Question 21

inadequate nutrition…

Answer 21

leaves humans vulnerable to toxic exposures

Question 22

what do many toxicants target?

Answer 22

target the mitochondria to disrupt neuronal function and survival

Question 23

how does retinoblastoma occur?

Answer 23

targets horizontal cells

over-proliferation of horizontal cells

Question 24

diseases affecting photoreceptors

Answer 24

retina pigmentosa

macular degeneration

Question 25

diseases affecting bipolar cells

Answer 25

stationary night blindness

Question 26

diseases affecting retinal ganglion cells

Answer 26

glaucoma

retina neuropathy

optic neuritis

Question 27

diseases affecting horizontal cells

Answer 27

retinoblastoma

Question 28

diseases affecting amacrine cells

Answer 28

nystagmus

glaucoma

Question 29

what is glaucoma?

Answer 29

optic nerve injury

Question 30

what part of the eye gets affected by lead?

Answer 30

lens