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Anatomy > Lecture 16 > Flashcards

Lecture 16 Flashcards

1
Q

what molecules give the gel like substance found in the vitreous?

A

PGs (hyaluronic acid) + water

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2
Q

the vitreous is what percent water? what percent is gel/liquid? what is the RI? transmits what percent of light?

A

98.5% water
80% gel/20% liquid (in a young eye, changes with age)
RI= 1.3349
90% (300-1400nm)

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3
Q

what components make up the vitreous?

A

water, Na+, K+, Cl-, bicarbonate, glucose, lactic acid, pyruvic acid, citrate, AA, main collagen type (TYPE 2) and other collagen types (TYPE 4 and 9)

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4
Q

what are the three different cell types located in the vitreous?

A
  1. halcotyes (type of phagocyte, synthesis of collagen and glycoprotein)
  2. fibrocytes (collagen synthesis)
  3. glial cells
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5
Q

fibrocytes and glial cells form what percent of cell population in vitreous?

A

10%

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6
Q

what is characteristic of primary vitreous?

A

vasculature forms (hyaloid vessels), VEGF released by the lens induces vasculagenesis, fibroblasts and halocytes form collagen.

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7
Q

what is characteristic of secondary vitreous?

A

anti-angiogenesis factor present (destroys blood vessels), hyaloid vessels retract, vitreous gel body formed

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8
Q

what is characteristic of tertiary vitreous?

A

formation of lens zonules.

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9
Q

the vitreous is attached most strongly to the retina in which location?

A

vitreous base (right at ora serratta almost)

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10
Q

where is the cortex of the vitreous? where is the patellar fossa? where is the canal of cloquet? where is bergers space?

A

extends on both sides of retina but does NOT cover optic canal, thins over macula
at back of the lens
runs through middle of vitreous, attaches at back of lens, and at optic disk in retina
space in canal of cloquet that it touching back of lens (held on by ligament of wieger)

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11
Q

cortex of vitreous is high in what? avg thickness?

A

density

200um

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12
Q

vitreous base of vitreous is attached to? what are its strong type of fibres? weak?

A

pars plana and inter limiting membrane of retina
strong fibres are perpendicular
weak are radial

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13
Q

what are the five vitreous attachments?

A

Big Lions Often Pick Fights
B= vitreous Base- strongest no age decline
L= ligament of Wieger- age decline
O= optic nerve (Wiess ring)- age related detachment
P= peripheral attachment- weak, poor blood flow and not in all people
F= fovea- macular holes

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14
Q

what holds the posterior vitreous onto the retina?

A

GLUE- consists of fibronectin, laminin, opticin, chondroitin sulfate, heparin sulfate and other ECM components.

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15
Q

from birth-2 years what consistency is the vitreous? at 2 years? 25 years? 65 years?

A

gel only
5% liquid
20% liquid
60% liquid

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16
Q

what is synchisis? sineresis? these two can lead to what?

A

synchisis- vitreous liquification
sineresis- vitreous collapse (due to spreading of collagen fibres with growth or aggregation of fibres, doesnt have to be liquified!)
posterior vitreal detachment

17
Q

ring shaped opacity is normally called what? cobwebs refers to? vitreal hemorrhaging can cause what effect? moving vitreous opacities are percieved when?

A 
wiess ring
condensation of collagen fibres
shower of minute red spots
(all of these are types of floaters)
they cause a shadow on the retina
18
Q

the vitreous acts as a HUGE support system for what?

A

RETINA (know the ways)

19
Q

the vitreous is vascular or avascular? is it metabolically active? where is O2 tension the highest? what is the percent of water turnover in vitreous?

A

avascular (therefore gets blood supply from aqueous and central retinal artery NOT choroid we dont want blood leaking in to disrupt transparency)
metabolically active
highest closest to retina
50% water turnover every 15 mins.

20
Q

what is unique about the diffusion in the vitreous?

A

it is slow (due to inhibiting gel), diffusion happens in all directions and smaller molecules will move faster.

21
Q

the highest concentration of Na+ ions is found where?

A

anterior portion of eye (due to output from ciliary processes, post lens and ant lens) therefore anterior ion concentration will want to diffuse (inhibited somewhat by gel) to posterior which is good for retina (diffusing nutrients)

22
Q

what makes the vitreous transparent?

A

98.5% water

soluble proteins and specific collagen/GAG configuration (very ordered and separation is maintained)

23
Q

what are common signs of rhegmatogenous (retinal tear)?

A
  1. flashes
  2. floaters (disturbing RPE therefore pigment may be floating around)
  3. peripheral vision defect
  4. VA normal unless the macula is involved
    (40% of patients notice nothing until black curtain effect occurs)
24
Q

how does non rhegmatogenous differ from rhegmatogenous?

A 
not due to vitreous tearing retina
secondary to diabetes or trauma
no age limit
develops slowly
no floaters
25
Q

what is exudative retinal detachment?

A

fluid produced somewhere in retina which separates retina from RPE (build up of lfuid in space between these two because these two are not tightly attached). gravity plays a major role. (exudates are like puss or runny nose, excretion)

26
Q

symptoms of exudative retinal detachment?

A
  1. absence of flashes
  2. sometimes floaters
  3. sudden visual field defect (depending on strength of inflammatory response)
  4. no retinal tears
27
Q

what is synchisis scintillans?

A

RARE (only seen in severely diseased)
not age related, vitreous extends up to the back of cornea and is filled with gold particles which are thought to be due to build up of cholesterol, impairs VA

28
Q

what is asteroid hyalosis?

A

stars in night sky
happens usually at ages 60-65, caucasian, does NOT impair VA, doesnt normally mean they have a disease but could be screened for things such as diabetes. Ca2+ build up

29
Q

what are 5 diseases that are due to embryonic remains?

A
  1. bergmeisters papillae (remenants of hyaloid artery on optic disc)
  2. persistant pupillary membrane (remains on pupil)
  3. mittendorfs dot (remains on posterior lens)
  4. cloquets canal (remains in vitreous)
  5. epicapsular scar (remains on anterior lens)

Anatomy (18 decks)

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