Retina Flashcards by Noelle Bock

layer of the retina where rod and cone membranes fuse together, creating an impediment to ion flow

external limiting membrane

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layer of the retina of cell bodies of the photoreceptors

outer nuclear layer

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layer of the retina where synapses are between photoreceptors and bipolar cells

outer plexiform layer

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layer of the retina where cell bodies of BP cells, horizontal cells, glial cells, amacrine cells are

inner nuclear layer

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layer of the retina with synapses between BP cells and ganglion cells

inner plexiform layer

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layer of the retina with the footplates of Mueller cells

internal limiting membrane

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rod free zone at 100 days before birth is:

large (1600 um in diameter)

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rod free zone at birth is:

still not adult like, 400-600 um in diameter

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rod free zone doesn’t reach adult like levels until:

200 days after birth (when it is 200 um)

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what is the cone like at 22 weeks gestation

looks like epithelial cells, no outer segments no photopigment, cannot transduce light

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how many days post birth is the cone the full length and pretty much adult like

45 days post birth

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describe changes in retina as it reaches ora errata

all retinal layers form down to a single layer to the non pigmented ciliary epithelium
-lose photoreceptors first, then INL/ ONL merge, then ganglion cells lost

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diameter of optic disc

1500 microns

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what layers does the central retinal artery (CRA) supply?

nerve fiber layer
ganglion cell layer
inner plexiform layer
inner nuclear layer
little of outer plexiform layer (by diffusion?)

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what are the cilia-retinal arteries?

coming from choroid and running to macula

- crossover vessel seen in 1/3 of population, usually see 1 but can see 2

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choroidal circulation includes what ciliaries

long posterior
anterior
short posterior

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2 main ways choroidal circulation is different than retinal circulation

a lot more choroidal vessels than central vessels

- choroidal vessels are larger- larger lumen diameter

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what layers does choroidal circulation supply?

photoreceptors and RPE

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size of retinal circulation capillaries vs. choroidal capillaries

retinal: smaller, < 10 nm
choroidal: larger, > 20 nm

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differences in circulation leakiness of choroidal versus retinal

choroidal circulation more leaky and the large molecules that pass out of circulation can not enter retina because of the RPE (tight junctions at base of RPE)

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mathematical formula for heart pressure

heart pressure= 80 + 1/3 (pulse pressure or 60) which =100

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what is clinical ophthalmodynamometry used to measure?

arterial diastolic pressure

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the small retinal vessels have what type of resistance and flow rate?

small vessels
high resistance
low flow rate (1.7 ml/min/gm)

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the large choroidal vessels have what type of resistance and flow rate?

large vessels
lower resistance
high flow rate (19 ml/min/gm)

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choroidal vasculature is under the control of the:

sympathetic nervous system (superior cervical ganglion)

relationship between IOP and blood flow in choroid

linear relationship | increased IOP = decreased blood flow

relationship between IOP and blood flow in retina

- no change between 20-70 mmHg because pericytes | - linear decrease in blood flow after 70

oxygen consumption rate of the retina

67 ul/gm/hr

glucose consumption rate of the retina

106 ug/mg/hr

70% of the oxygen consumed in the retina is used for:

glucose oxidation

80% of the glucose used in the retina goes through:

glycolysis | other 20% goes to pentose shunt

photoreceptors use ___ the energy produced in the retina

half

neurotransmitter for photoreceptors

glutamate

neurotransmitter for bipolar cells

glutamate

neurotransmitter for horizontal cells

GABA

neurotransmitters for amacrine cells

Ach, dopamine, noradrenalin, serotonin, GABA, glycine, aspartate, taurine

neurotransmitters for ganglion cells

glycine, aspartate, taurine

ERG: | A-wave is from the

photoreceptors | (-) wave

ERG: | B-wave is from the

bipolar cells and Mueller cells | (+) wave

ERG: | C-wave is from the

RPE

ERG: | D-wave is from the

off response (light going off retina)

ERG: | oscillatory potentials are from the

amacrine cells | b/w A and B wave in the ascending limb of B wave

flash ERG used for

mueller cells | -retinal dystrophies such as retinitis pigments, Stargardts, Bests

pattern ERG used for

ganglion cells | -glaucoma, diabetes

multifocal ERG used for

cones, cone BP cells | -macular dystrophy

type of occlusion with sudden loss of vision, ischemic retina with macula as cherry red spot

retinal artery occlusion

what is the order of ERG drop out in retinal artery occlusion

- oscillatory potentials first (amacrine cells most sensitive to lack of oxygen) - b wave - a wave does not disappear (b/c photoreceptors get nourished from choroid)

type of occlusion with extensive retinal hemorrhages, dilated veins, possible cotton wool spots

retinal vein occlusion

in an ischemic retinal vein occlusion, what ERG change can you see?

decrease in B wave amplitude

as the glucose level is decreased in the retina, when do you see B-wave and A-wave disappear?

B-wave after 15 minutes without glucose A-wave gone after 30 minutes (because Mueller cells more sensitive to lack of glucose than photoreceptors)

how many amino acids in sequence of opsin

348

where does vitamin A bind to opsin

296th amino acid in sequence (lysine)

opsin: where are amino terminal and carboxyl terminal

amino: inside disc carboxyl: outside disc (in cytoplasm)

1 rhodopsin can generate ____ T-GTPs

500

1 rhodopsin can break down ___ cGMPs

1 million

the disc is 50% protein, and 85% of that protein is:

rhodopsin

the disc is 50% lipid, and that lipid is:

phospholipid, so that membrane is fluid

difference in rod shedding versus cone shedding

- rods shed when light comes on | - cones shed with light goes off

how many days is life cycle of disc production?

9-13

3 functions of RPE

1. discs that are shed from photoreceptors are phagocytized by RPE 2. RPE contains melanin- decreases light scatter 3. vitamin A storage, all-trans retinol-regeneration of rhodopsin

most common inherited disease affecting RPE

retinitis pigmentosa

where retinitis pigmentosa usually begins:

mid-periphery (20 degrees from fovea where highest concentration of rods are)

possible chromosomes affected by genetic mutation in retinitis pigmentosa

1-11, 14-17, 19, X

retinitis pigmentosa | % X linked recessive and types

10% 2 types short arm of X chromosome

retinitis pigmentosa | % autosomal dominant and types

20% | over 70-100 types

retinitis pigmentosa | % autosomal recessive

15%

retinitis pigmentosa | % undetermined

50%

common proteins affected in retinitis pigmentosa

- proline (CCC) -> histadine (CAC) point mutation | - RDS or cGMP

common signs of retinitis pigmentosa

- blood vessels thinner and less blood to retina - optic disc pale - cells in vitreous floating around - posterior subcapsular cataract (PSC)- 50% of people

what is the most clinically significant test for retinitis pigmentosa

ERG (16-18% decrease per year) | after ERG flatlines, then do VFs

in electroculargrams done for retinitis pigmentosa, what ARDN ratio is considered abnormal?

< 1.7

inheritance pattern and cause of Bests disease

autosomal dominant | -macula not normal from increased lipofuscin

Retina Flashcards

(72 cards)