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Ocular Anatomy > Lecture 10: RPE > Flashcards

Lecture 10: RPE Flashcards

1
Q

what are the 10 layers of the retina

A
  1. Internal limiting membrane (ILM)
  2. Nerve fiber layer (NFL)
  3. Ganglion cell layer (GCL)
  4. Inner plexiform layer (IPL)
  5. Inner nuclear layer (INL)
  6. Outer plexiform layer (OPL)
  7. Outer nuclear layer (ONL)
  8. External limiting membrane (ELM)
  9. Photoreceptor layer (PR)
  10. Retinal Pigmented epithelium (RPE)
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2
Q

the RPE (10th layer of the retina) is what type of layer?

A

Monolayer of polarized cuboidal cells that separate photoreceptors from their underlying blood supply (choroid)

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3
Q

what are the 6 RPE functions

A
  • Absorption of stray light
  • Protection against toxic and oxidative damage
  • Blood-retina-barrier
  • Selective transport of substances to and from the retina
  • Elimination of metabolic waste
  • Processing Vitamin A metabolites
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4
Q

cell density is greatest where

A

fovea (~5000 cells/mm2)

peripherally (~2000 cells/mm2)

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5
Q

Are RPE and PRs are arranged apex- to-apex or base to base? what is this due to… and what is the result of this?

A

RPE and PRs are arranged apex- to-apex due to embryoloigcal development. Thus, a potential space, the subretinal space, is located between them.

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6
Q

what fills the subretinal space? what does it control?

A

Interphotreceptor matrix fills the space, is very strong, but no junctions. Controls trafficking of nutrients

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7
Q

RPE basement membrane is innermost layer of what?

A

Bruch’s membrane

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8
Q

RPE extends from

A

ora serrata (transitions from pigmented ciliary epithelium) to just before the optic disc

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9
Q

what is at the apical end of the RPE projecting between the OS of PRs

A

microvilli

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10
Q

Apical Membrane Specializations

A

Apical Na+/K+ ATPase pumps

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11
Q

Each RPE cell faces how many PRs

A

30-40 PRs

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12
Q

when do rods and cones shed?

A
  • Rod discs are shed in the early morning

* Cone discs are shed during the evening

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13
Q

why is the RPE cell unique

A

it has Na+/K+ATPase pumps on its apical surface.

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14
Q

why is a Na+/K+ATPase pumps on its apical surface of RPE needed?

A

To regulate fluxes to keep the sensory retina (PR) adhered to the RPE

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15
Q

nutrient in

A

waste out

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16
Q

RPE does what to PR discs?

A

RPE digests, and recycles PR discs

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17
Q

what happens if the RPE can’t do its job?

A

If RPES can’t do its job it will dump the partially digested materials (hydrophobic) onto bruch’s membrane (DRUSEN), if stays within the cell

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18
Q

Drusen =

A

lipofuscin (increases with age)

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19
Q

what are the 10 ultrastructure features of the RPE

A
  1. apical microvilli
  2. lysosome
  3. junctional complex and terminal bar
  4. phagosomes
  5. melanin granules
  6. lipofuscin
  7. golgi apparatus
  8. basal infoldings
  9. RER and SER
  10. mitochondria
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20
Q

Ultrastructure function: apical microvilli

A

aids adhesion, phagocytosis, increased SA for metabolic exchange

21
Q

Ultrastructure function: lysosome

A

contains hydrolytic enzymes which digest PRs

22
Q

Ultrastructure function: junctional complex and terminal bar

A

component of blood- retinal barrier and ensures cell-cell adhesion

23
Q

Ultrastructure function: phagosomes

A

contains phagocytosed PR segments

24
Q

Ultrastructure function: melanin granules

A

absorbs excess visibile light and UV – reduces free radical damage

25
Q

Ultrastructure function: lipofuscin

A

‘ageing pigment’, residual bodies from phagocytotic activity

26
Q

Ultrastructure function: golgi

A

secretion and sulphation of GAGs

27
Q

Ultrastructure function: basal infoldings

A

increase surface area for cell absorption and secretion

28
Q

Ultrastructure function: RER/SER

A

protein and lipid synthesis

29
Q

Ultrastructure function: mitochondria

A

large numbers indicate active ‘pumping’ epithelium

30
Q

Lateral membrane (specialization of RPE): tight junction

A

blood - retina - barrier

31
Q

RPE: blood -retina- barrier has tight junctions between what two cells

A
  • Tight junctions (zonulae occludentes) between the RPE cells
  • Tight junctions between the non-fenestrated endothelial cells of the retinal capillaries
32
Q

TF: Retinitis pigmentosa (PR) is an autosomal recessive retinal dystrophy

A

F: An autosomal dominant retinal dystrophy

33
Q

what is a progressive loss of RPE and PR function

A

Retinitis pigmentosa

34
Q

RP Apoptosis:

A

rods and cones

35
Q

Functional in peripheral retina

A

rods

36
Q

functional in the Fovea

A

cones

37
Q

“tunnel vision”

A

RP

38
Q

(RP) Bone-spicule pattern:

A

RPE degenerates

and pigment migrates and deposits around blood vessels

39
Q

RP treatment:

A

• To slow down progression

• High Doses of VitaminA (15000
IU/day)

• DHA, Omega 3, Vit C 1000mg, Lutein, Zeaxanthine (no solid evidence)

40
Q

Congenital hypertrophy of the retinal pigmented epithelium (CHRPE) lesions are typically

A

solitary, flat, well-demarcated, hyperpigmented lesions of the retina, seen in a grouped configuration like “bear tracks”

41
Q

Both solitary lesions and “bear tracks” are

A

benign

42
Q

multiple, bilateral lesions can be associated with Gardner’s syndrome

A

an autosomal dominant disease which invariably results in colon cancer by the fifth decade of life

43
Q

Retina:

A

window into CNS and Cardiovascular systems

44
Q

retinal detachment (RD) usually separate at

A

RPE and PR

layer (as no intracellular junctions)

45
Q

T/F: RPE remain attached to choroid and

can not be separated without difficulty

A

T: RPE remain attached to choroid and

can not be separated without difficulty

46
Q

RD separates PR from their blood

supply, if not attached quickly what will happen to PR cells

A

if not attached quickly PR cells

will necrose and die

47
Q

Argon laser is used to produce scar at

edges of RD to prevent

A

enlargement

and to reposition the layer

48
Q

what can be used to reattach the retina and prevent fluid leakage in to breaks and subretinal space

A 
Silicon oil (72% success rate) or gas
temponade perfluropropane (87% success)

Ocular Anatomy (15 decks)

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