Retinal Histology Flashcards
Ora serrata
anterior, non-sensory retinal pigmented epithelium located just posterior to the cilliary body
can lance with needle w/o damage to vision
Macula Lutea
area around the fovea
high density of cones
vessels form thin loops at the periphery
center=fovea
Optic disc
where the optic n. and vessels enter the eye
no photoreceptors, bipolar cells, or ganglion cells. only unmyelinated axon
layers of the retina
from exterior (posterior) to interior (anterior)
1) Pigmented epithelial cells
2) photoreceptors
3) outer limiting membrane
4) outer nuclear layer
5) outer plexiform layer
6) inner plexiform layer
7) ganglion cell layer
9) optic n. fibers
10) inner limiting membrane
Interphotoreceptor matrix
connection bw the photoreceptor and RPE
important for recycling of older discs and transports retinol to RPE and retinal to photoreceptors via interstitial retinoid binding protein
contains melanin which absorbs light and prevents it from being reflected back into eye
Retinal pigmented epithelium
contain melanin granules
phagocytose and shed discs (in lysosomes) released into choriocapillaries
converts retinol to retinal
photopsin
the opsin protein that is in cones
with chromophore 11-cis retinAL it is caled iodopsins
bleaching
photopigment can absorb a photon of light and change conformation
i.e. changes retinol into retinal allows photopigment to acts as GPCR converts cGMP to GMP closes cGMP sensitive Na channes to close hyperpoloarizes cell decreased NT release
Rhodopsin
photopigment present in the discs
contains 1) Opsin 2) retinal
which opsin is present determines wavelength absorbed
called photopsin in cones
Leber congenital amaurosis type 2
mutations in the RPE65
prevents you from isomerizing trans to cis in the RPE retinal
bipolar cell
receive impulse from photoreceptor cell
diffuse cone BP and rod BP get input from multiple photoreceptors and synapse on multiple gnaglion cells
midget cone bipolar get info from one cone and synapse on one ganglion cell
ganglion cells
dendrites in the inner plexiform layer
diffuse ganglion cells contact several BP cells
Midgit ganglion contact one BP
association neurons
integrate signaling
amacrine cells and horizontal cells
amacrine cells
neuites ending axon terminals of BP cells and ganglion cell dendrites and bodies
horizontal cells
neurites ending on cone pedicles and rod spherules
Glial cells
mueller cells and microglia
fovea
on visual axis of cornea
depression of retina, flatteing of inner layer to let more light in
highest density of cones which means high visual acuity
poor low light
fovea centrais
highly packed cones arranged at an angle to pigmented layer
outer nuclear layer of the retinal do no obstruct light pathway
optic n.
convergence of axons of retinal ganglion cells
unmyelinated affarents, myelination begins at disc (area of no photoreceptors)
central retinal a
provides blood to inner parts of retina
branches run posterior to the inner limiting membrane
Retinal detachment
detachment of the photoreceptors from the RPE
lack of nutrients cause retinal cells to die
preproliferative Diabetic retinopathy
nonproliferative
increased size and number of intraretinal hemorrhages, but limited vision loss
much of vision loss occurs due to macular edema
Age related macular degneration
when photoreceptors and RPE break down (can be due to Drusen) (dry) or when abnormal blood vessels grow and leak under the macula (wet)
causes rapid and painless vision loss
Proliferative Diabetic retinopathy
formation of new blood vessels
can protrude into the vitreous and cloud vision and detach retina
may even extend into more anterior structures
Diabetic retinopathy
microaneurisms (outpouching of retinal capillaries)
cotton wool spots (ischemia) dilated retinal veins lack of perfusion of retinal aa. loss of pericytes apoptosis of capillary endothelial cells
Hyperglycemia-induced intramural pericyte death and thickening of the basement membrane lead to incompetence of the vascular walls
