RPE Flashcards
What is the outermost layer of the retina
RPE
What is the RPE a barrier between
Choroid and retina
What needs to be done in order to assess the RPE
Eye needs to be dilated
Where is the RPE present in the retina
Anywhere the retina is present, the RPE is present
RPE at the optic nerve
No retina optic nerve, thus no RPE
Light getting to the retina
Light must pass through all of the layers of the retina to reach the RPE
Vitreed
Towards the vitreous
Sclerad
Towards the sclera
Outer
Away from center of the ye
Inner
Towards center of eye
What is the RPE rich with
Melanocytes
What are the layers of the retina from inner to outer
Inner limiting membrane Nerve fiber layer Ganglion cell layer Inner plexiform layer Inner nuclear layer Outer plexiform layer Outer nuclear layer Outer limiting membrane Layer of rods and cones Pigmented epithelium
What is the peripheral retina continuous with
RPE continuous with PE of ciliary
Other nine layers are continuous with NPE of ciliary body
How many layers to the RPE
One
How many cells in the RPE
4-6 million, don’t regenerate
Where is the RPE cell density the greatest
In the fovea
How many photoreceptor outer segments does each RPE cell face
About 30-40
What does the RPE do to the outer segment of the photoreceptors
Engulfs shed discs from photoreceptors on a daily basis
When does the rod shed its discs that get engulfed
Morning
When do the cones shed their disc that get engulfed
Night
What does the apex of the RPE face
Apex of the photoreceptor outer segment
What are the layer of bruchs membranes
RPE BM Inner collagenous zone Elastic zone Outer collagenous layer BM of choriocapillaris
What are some roles of the RPE
Secretion Phagocytosis Visual cycle Glia Epithelial transport Light absorption
What are the layers of the RPE
Outer zone
Middle zone
Inner zone
What is in the outer zone of the RPE
Mitochondria
What is in the middle layer of the RPE
Nucleus
Golgi
ER
What is in the inner layer of RPE
Melanocytes
Where is the degradation of rod outer segment
Lysosomal degradation in the RPE. Phagosome and lysosomes come together and form a secondary lysosome and digestions
Metabolic waste deposited in inner collagenous zone of Bruch’s membrane
Drusen
Drusen and age
Normal with age
Excess is problem-RPE not functioning, smokers have mroe
Familial dominant druses
Hereditary
Nothing to do about it
Usually no vision complaints
ARMD
Build up of hydrophobic stuff in Bruch’s membrane. Waste cant get out, nutrients cant get out. Cracks form in Bruch’s, blood vessels form though cracks. They are fenestrated, so stuff leaks into RPE. Fluid, blood, protein. If in macula, obstrustus vision
What is the difference between dry and wet AMD
Dry is just drusen
Wet is blood vessels in macula
Geographic atrophy
Dropout of of RPE, choroidal vessels show through
What is treatment for wet AMD
Injectable anti vascular endothelial growth factor (anti-VEGF)
What are 3 common VEGF inhibitors
Avastin
Eylea
Lucentis
What is a cheap alternative to anti VEGF treatment
Avastin is used for colon cancer, but it is 50$ compared to $2000 and does the same thing
Visual distortion causes by AMD
Metamorphopsia (blurred)
Scotoma (loss)
What do we use to test AMD
Master grid
How are RPEs and photoreceptors arranged
Apex to apex due to embryolongical development
What fills the space between the RPE and PRs
Interphotoreceptor matrix
What is interphotoreceptor matrix
Fills the space between RPE and PRs, very strong, but no junctions. Controls trackificing of nutrients
Apical membrane specializations
Apical Na+/K+ ATPase pumps
What do the apical Na+/K+ ATPase pumps do
Regulate fluxes to keep the sensory retina adhered to the RPE
Lateral membrane specializetions of the RPE
Zonula occludens
- tight junction
- blood barriers
What are all the different types of junctions in the lateral RPE membrane
Zonula occludens Zonula adherens Macular adherens Gap junction Focal adhesion Bruch's membrane
These increase surface area for cell absoprtion and secretion
Basal enfoldings
Blood retina barrier
- Tight junctions between the RPE cells ( zonula occludens)
- tight junctions between the non fenestrated endothelial cells of the retinal caps
Function of the apical microvilli
Aids adhesion, phagocytosis, increased surface area for metabolic exchange
Function of lysosomes
Contain hydrologic enzymes which digest photoreceptors
Function of phagosomes
Contain phagocytosed photoreceptor segments
Function of Golgi
Secretion and sulphation of GAGs
Function of basal infoldings
Increases absorptive surface
Retinitis pigmentosa
- Photoreceptors gone
- RPE too close to second order neurons, so RPE migrate to inner retina and surround the blood vessels
- occlude the ganglion cell blood vessels
- rod receptor problem
- tunnel vision
Benign hypertrophy of RPE (bear tracking)
Hyper pigmentation of RPE
Normal ish
Choroidal Nevis
Normal freckle thing
Choroidal melanoma
Has thickness to it. Can see pigment forming. Immediate referreral
Histoplasmosis
- fungal infection
- peripapillary atrophy
- central and peripheral