RPE I Flashcards
What is RPE
The outermost layer of the Retina that separates it from the choroid
T/F anywhere that retina is present RPE is also present
True
Is there retina at the optic nerve?
No, so no RPE either
What must light pass through to reach the RPE
All the layers of the retina
What are the layers of the retina from inner to outer
Inner: inner plexiform layer Inner nuclear layer Outer plexiform layer Outer nuclear layer Inner segments Outer segments Outer: RPE
Non pigmented ciliary epithelium is continuous with this
Retina
The pigmented epithelium is continuous with this
RPE
Approximately how many RPE cells do we have?
4-6 million
Do RPE have the ability to regenerate
No
Where is the RPE cell density the greatest
At the fovea
How photoreceptors face a single RPE cell
30-40
Apex of the RPE faces this
Apex of the photoreceptors outer segment
What are the major functions of the RPE cells
Secretion (VEGF and PEDF) Phagocytosis (of metabolic wastes) Visual cycle Glia Epithelial transport (H2O, Cl, vitamin A, glucose) Light absorption
What photoreceptor discs are shed in the morning
Rod discs
What photoreceptor discs are shed in the evening
Cone discs
When are our rods used
At night in dark environments
When do we use our cones
In the daytime bright conditions
What are present in th outer zone of the RPE
Mitochondria
What are present in the middle zone of RPE
Nucleus of RPE, Golgi and ER
What are present in the inner zone of the RPE
Melanocytes
Know what a drusen is
See slides 21-23
What happens in macular degeneration
You have a buildup of hydrophobic materials in Bruchs that causes the RPE to malfunction and become sick and nutrients cant come in and wastes cant get out. This can cause cracks to corm in Bruch’s membrane, where blood vessels will creep in
What happens in geographical atrophy
RPE drop out and you can see choroid
What is the difference between wet and dry MD
Wet: there are blood vessels that creep into the macula
Dry: just drusen
How do you treat Wet AMD
Injectable anti-VEGF drugs
What are the 3 anti-VEGF drugs used to treat MD
Avastin
Eylea
Lucentis
How do anti-VEGF treatments work
They seek out harmful VEGF molecules and block them.
This reduces abnormal growth and leakage, which helps stabilize vision loss and improve sight
What is the cost difference between the anti-VEGF injections
Avastin is the cheapest
Eylea and lucentis are very expensive
What are some visual distortions that occur with AMD
Metamorphopsia
Scotoma
How are RPE’s arranged
Apex to apex due to embryological development
What fills the subretinal space and what is its job
Interphotoreceptor matrix
It controls trafficking of nutrients
What makes up the basement of the RPE
The innermost layer of Bruch’s membrane
What are some apical membrane specializations in the RPE
Na/K ATPase pumps: regulate influxes to keep the sensory retina adhered to the RPE
What are some lateral membrane specializations of the RPE
- Tight junctions: blood retina barrier
- zonula occludens
- zonula adherens
- macular adherens
- Gap junctions
- Focal adhesion
- Bruch’s membrane
What are some basal membrane specializations that are in the RPE
Basal enfoldings (increase SA for cell absorption and secretion)
What creates the Blood retina barrier
Tight junctions between the RPE cells and between the non-fenestrated endothelial cells of the retinal capillaries
What is the function of apical microvilli
Aids in adhesion, phagocytosis, increase SA of exchange
What is the function of lysozymes in RPE
Contain hydrologic enzymes that digest photoreceptors
What is the function of junctions complex and terminal bar in RPE
Part of B-R-B and ensures cell-cell adhesion
What is the function of phagosomes in RPE
Contain phagocytosed photoreceptor segments
What is the function of melanin granules
Absorb excess visible light and UV
Reduces free radical damage
What is the function of lipofuscin in RPE
Aging pigment
What is the function of the Golgi in RPE
Secretion and sulphation of GAGs
What is the function of rough and smooth ER in the RPE
Protein and lipid synthesis
What is the function of mitochondria in RPE
Large numbers indicate active pumping epithelium
Look at slides for conditions
Slide 44-49