Retina and Vitreous Vol. 2 Flashcards Preview

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

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

A

Cones

2
Q

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

A

Rods

3
Q

What creates the internal limiting membrana (ILM)?

A

Footplates of Muller calls

4
Q

What creates the external limiting membrana (ELM)?

A

Zonular attachments between photoreceptors and Muller cells

5
Q

What creates the appearance of the middle limiting membrane?

A

Synaptic connection between the photoreceptors and the bipolar cells

6
Q

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

A
  1. Ganglion cell layer/NFL 2. Inner nuclear layer
7
Q

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

A

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

8
Q

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

A

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

9
Q

What is the embryologic origin of the RPE?

A

Neuroectoderm

10
Q

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

A

Pigmented epithelial layer of the ciliary body

11
Q

Where is the apical layer of the RPE located?

A

On the side of the photoreceptors

12
Q

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

A

RPE cells become taller and denser in the macula

13
Q

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

A

Zonulae occludentes

14
Q

What structures form the outer retinal blood-ocular barrier?

A

Zonulae occludentes

15
Q

What is the function of melanosomes of the RPE?

A

Absorption of light

16
Q

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

A

Blue light

17
Q

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

A

Rayleigh absorption (e.g. shorter wavelength)

18
Q

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

A

Dawn

19
Q

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

A

Dusk

20
Q

What does A2E form in the RPE?

A

Lipofuscin

21
Q

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

A

RPE

22
Q

What causes the bone spicule appearance of retinitis pigmentosa?

A

Hyperplasia of RPE cells that envelope the retinal vessels

23
Q

Patient with RPE abnormalities and intestinal polyposis

A

Think Gardner syndrome

24
Q

Name the 5 layers of Bruch’s membrane.

A
  1. Basement membrane of the RPE 2.Collagen 3.Elastic fibers 4.Collagen 5.Basement membrane of the choriocapillaris
25
Q

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

A

Pseudoxanthoma elasticum

26
Q

Through what vessels does blood enter the choroid?

A

Short posterior ciliary arteries

27
Q

What is the outer layer of choroidal vessels known as?

A

Hailer layer

28
Q

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

A

Sattler layer

29
Q

Where is the choroid the thinnest?

A

Ora serrata (0.1 mm)

30
Q

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

A

0.22 mm

31
Q

Where do the capillaries of the choroid drain into venules?

A

Choriocapillaris

32
Q

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

A

Choroid

33
Q

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

A

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

34
Q

What is the most common intraocular tumor in adults?

A

Melanoma

35
Q

How many vortex veins does the each eye contain?

A

4 or 5

36
Q

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

A

Nanopthalmos

37
Q

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

A

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

38
Q

What structures mark the equator of the globe?

A

Vortex veins