Retinal Topography And Vasculature Flashcards by Jeremy Penn

Neural tunic of the eye?

Retina

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The retina is important to optometrists because it’s the window into the…

CNS and cardiovascular system

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Light energy being transformed into a neural signal

Phototransduction

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Where is the neural signal modified from light energy?

Within the retina

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What are the 1st 3 cells of the visual pathway within the retina?

1st - photoreceptors

2nd - bipolar cells

3rd - ganglion cells

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What is the importance of neuroglial cells in the retina?

To maintain and buffer the environment

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How many layers are there of the retina?

It’s divided into 2 categories, what are they?

10 layers.

Inner 9 are the Sensory/Neural Retina

Outermost 10th is the RPE

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___________________ span the Outer Retina. What layers are in the Outer retina?

Photoreceptors

Photoreceptor layer, external limiting membrane, outer nuclear layer, and outer plexiform layer

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What is the role of photoreceptors?

To absorb light photons and convert them into an electrochemical even (nerve signal)

Phototransduction!

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What are the 2 kinds of photoreceptors in the retina?

Rods and cones

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How many cones are there? What type of illumination are they used for?

5-6 million, 10% in fovea

Bright! And color.

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What are the 3 photopigments stored in the disc membrane that are sensitive to different wavelengths?

Conopsins:

S-cones (blue) 420 nm
M-cones (green) 531 nm
L-cones (red) 588 nm

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What type of photoreceptors are only found in the Fovea?

Cones!

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What type of conopsins are not found in the center of the fovea?

S-cones

Only M and L cones

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What is the test used to tell a normal eye from a dichromat eye? What Photoreceptor are you testing?

Ishihara plate

Cones

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How many rods are there? What type of illumination do they sense?

92-120 million

Dim vision, scotopic.

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What type of photopigment is located in the disc membrane of the rods? What wavelength do they sense?

Rhodopsin

498 nm

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Where is the peak density of cones on the retina?

A ring about 4.5 mm outside the fovea. Where macular degeneration usually occurs

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Are there rods in the fovea?

No! Just CONES

The 2nd neuron cells are the..

Cone/rod bipolar cells

The 3rd neurons are the…

Retinal ganglion cell layers (they’re the major output cells)

What layer of the retina starts to die off in Glaucoma?

Retinal ganglion cell layer

Retinal thickness ranges from __ microns to ___ microns. Where is it the thinnest and thickest?

80 to 320 microns.

Thinnest- ora serrata (80)

Thickest - foveal rim (320) (fovea is only 150-200 microns)

What is the central retina?

Posterior Pole or Macula or Area Centralis

Dense population of cone photoreceptors

Color vision and fine detail

Where is color vision and fine detail discriminated?

Central retina/macula/posterior pole/area centralis CONES

What is the peripheral retina?

Dense population of rod photoreceptors outside of the macula. For night vision and motion detection

What part of the retina is for night vision and motion detection?

Peripheral retina

What is the only area of the retina to contain more than 1 layer of retinal ganglion cells?

Macula

The macula contains high levels of...

Carotenoids

In the fovea, the walls slope giving rise to the light reflex known as...

Foveal reflex

In the fovea, the sloping is known as: The center is the:

Clivus Foveola

Part of the fovea where there is dense packing of cones that makes them appear rod-like in structure

Foveola

Where can you find the high accumulation of bipolar and retinal ganglion cells?

Parafovea. Extends 0.5 mm rom foveal rim

Cone inner fibers that are oriented within the fovea are called: The OPL in the fovea is often referred to as:

Henle fibers. Henle' fiber layer. Nice.

Where does the peripheral retina terminate?

Ora serrata

The retina has a high demand for _________ . The outer retina is supplied by the ___________. Then inner retina is supplied by __________ ________.

Oxygen Choroid Retinal vessels

Are artery supplies the macula?

Cilioretinal artery

What artery enters the eye through an aperture in the lamina cribrosa of the optic disc? This artery is position slightly _________ in the nerve.

Central Retinal Artery Nasal

What is the artery:vein ration in the eye?

2:3

The Central Retinal Artery loses its __________ ____________ as it enters they eye, and is replaced with a _________ _________.

Tunica elasticum. (Internal elastic shell) This is what's distinguishes it from other muscular arteries in the body Tunica media (smooth muscle to enhance constriction of vessel)

What is the outermost later of blood vessels? Is it thicker/thinner in veins?

Tunica adventitia. (Connective tissue) Thicker in veins

Control of vasomotor tone is ________________ in the retina, unlike the choroid, where it is _______________.

Autoregulated Neuroregulated

3 parts of retinal capillaries

1. Endothelium 2. Basal lamina 3. Pericytes

These structures expand and contract on the capillaries in the retina and are sensitive to Aldose Reductase. What problems are prevalent here due to sugar?

Pericytes Diabetes!

Macular edema can lead to a ____________ shift

Hyperopic