Retina and Vitreous Vol. 2 Flashcards Preview

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Flashcards in Retina and Vitreous Vol. 2 Deck (38):
1

What type of photoreceptor makes a one-to-one synapse on bipolar cells?

Cones

2

What type of photoreceptor is associated with making multiple synpases on a single bipolar cell?

Rods

3

What creates the internal limiting membrana (ILM)?

Footplates of Muller calls

4

What creates the external limiting membrana (ELM)?

Zonular attachments between photoreceptors and Muller cells

5

What creates the appearance of the middle limiting membrane?

Synaptic connection between the photoreceptors and the bipolar cells

6

Where are the two layers of capillaries of the retina located?

1. Ganglion cell layer/NFL 2. Inner nuclear layer

7

How is oxygen tension of the outer retina related to amount of light?

Oxygen tension of the outer retina decreases with dark (e.g. approaching zero)

8

What percentage of the oxygen used in the fundus is provided by the retinal vascular system?

Approx.5% (the rest provided by the choroid)

9

What is the embryologic origin of the RPE?

Neuroectoderm

10

What does the RPE become continous with at the ora serrata?

Pigmented epithelial layer of the ciliary body

11

Where is the apical layer of the RPE located?

On the side of the photoreceptors

12

How does the shape of RPE cells change in the macula?

RPE cells become taller and denser in the macula

13

What structures connect the RPE cells together at the apical surface?

Zonulae occludentes

14

What structures form the outer retinal blood-ocular barrier?

Zonulae occludentes

15

What is the function of melanosomes of the RPE?

Absorption of light

16

What color of light is the most absorbed by the RPE?

Blue light

17

What accounts for the fact that the RPE absorbs blue light better than red light?

Rayleigh absorption (e.g. shorter wavelength)

18

At what time of the day do rods shed their outer segments?

Dawn

19

At what time of the day do cones shed their outer segments?

Dusk

20

What does A2E form in the RPE?

Lipofuscin

21

Where does most of the regeneration of 11-cis? ratinaldehyde from 11-trans? retinaldehyde occur?

RPE

22

What causes the bone spicule appearance of retinitis pigmentosa?

Hyperplasia of RPE cells that envelope the retinal vessels

23

Patient with RPE abnormalities and intestinal polyposis

Think Gardner syndrome

24

Name the 5 layers of Bruch's membrane.

1. Basement membrane of the RPE 2.Collagen 3.Elastic fibers 4.Collagen 5.Basement membrane of the choriocapillaris

25

What condition is associated with increased fragility of Bruchs' membrane?

Pseudoxanthoma elasticum

26

Through what vessels does blood enter the choroid?

Short posterior ciliary arteries

27

What is the outer layer of choroidal vessels known as?

Hailer layer

28

What layer of the choroid does the Haller layer merge with?

Sattler layer

29

Where is the choroid the thinnest?

Ora serrata (0.1 mm)

30

What is the maximal thickness of the choroid at the posterior pole?

0.22 mm

31

Where do the capillaries of the choroid drain into venules?

Choriocapillaris

32

What has the highest blood flow rate of any tissue in the body?

Choroid

33

What cells are the exposed to the highest oxygen tension that any other part of the body?

RPE cells {e.g. increases risk of oxidative damage)

34

What is the most common intraocular tumor in adults?

Melanoma

35

How many vortex veins does the each eye contain?

4 or 5

36

What condition is associated with small eye with excessively thickened sclera?

Nanopthalmos

37

What complication can be caused by the thickened sclera of nanophthalmos?

Uveal effusion syndrome (eg.due to impaired passage of fluid through the sclera)

38

What structures mark the equator of the globe?

Vortex veins