Vitreous Flashcards
The vitreous body makes up approximately ____ of the volume of the eye and thus is the ______ single structure of the eye.
a. 10%, smallest
b. 90 %, largest
c. 80%, smallest
d. 80%, largest
e. 90%, smallest
d. 80%, largest
The length of the vitreous body in the newborn eye is approximately _______mm and by the age of 13 years, the actual length of the vitreous increases to ____mm
a. 16.1 mm, 10.5mm
b. 12.1 mm, 15,1mm
c. 10.1 mm, 16.1 mm
d. 10.5 mm, 16.1 mm
d. 10.5 mm, 16.1 mm
The mean adult vitreous is ____ mm.
a. 12.5 mm
b. 14.5 mm
c. 16.5 mm
d. 18.5 mm
c. 16.5 mm
The vitreous is actually ~_____ water.
a. 75%
b. 80%
c. 90%
d. 98%
d. 98%
The major non-aqueous biochemical components: fibrinogen/collagen and Glucosamine/Glycosaminoglycans (GAGs) form the vitreous into a gel that has important viscoelastic/ viscoplastic properties.
collagen, Glycosaminoglycans (GAGs), viscoelastic
The gel content increases/decreases with age.
decreases
T/F In the human, liquefaction is already at 20% (volume) by around age 18 and progresses to greater than 50% by the 80th decade.
True
T/F The existence of a gel in the vitreous does not depend on interactions between GAGs and collagen.
False, does depend
Type ____ collagen accounts for ____ of the total vitreal collagen and is the principal “structural” collagen present.
a. III, 75%
b. I, 50%
c. II, 75%
d. II, 50%
c. II, 75%
T/F Type II collagen is essential to gel formation in the vitreous.
True
Combined types V/XI collagen represent ~____ of the collagen present.
a. 10%
b. 20%
c. 30%
d. 40%
a. 10%
T/F A difficulty with investigating the vitreous body is that any attempts to define vitreous morphology are in fact attempts to visualize a tissue, which by design is intended to be visible.
False, invisible
T/F A difficulty with investigating the vitreous body is the various techniques that have previously been used to define the structure of the vitreous body are combined with artifacts that make interpretations difficult in terms of the true in vivo physiologic situation.
True
In the late/early stages of embryology, the optic cup is mainly occupied by the retina/lens vesicle.
As the optic cup grows, the space formed is filled by a system of bony/fibrillar material, presumable secreted by the cells of the embryonic retina/cornea.
early, lens, fibrillar, retina
T/F The penetration of the hyaloid artery, more fibrillar material, and other vessels all contributes to filling the space, known as the primary vitreous.
True
The size of the vitreous cavity increases and the hyaloid vascular system regresses developing the primary/secondary/tertiary vitreous.
secondary
T/F The main hyaloid artery remains for some time, but it eventually disappears and leaves in its place a tube of primary vitreous surrounded by the secondary vitreous, running from the retrolental space to the optic nerve. The tube is called Cloquet’s canal.
True
The Cloquet’s canal: a tube of primary/secondary vitreous surrounded by secondary/tertiary vitreous running from the retrolental space to the optic nerve.
primary, secondary
T/F The vitreous is the suspensor fibrils that suspend the lens, are developed from the fibrillary material.
False, Zonules
Zonules of the lens are termed the primary/secondary/tertiary vitreous.
tertiary
The mature vitreous body is a opaque/transparent gel and is spherical except at anterior/posterior end which is concave/convex .
transparent, anterior, concave
The innermost/outermost part of the vitreous, called the cortex, is divided into an anterior cortex and a posterior cortex, the latter being approximately 100/200 µm thick.
outermost, 100
The vitreous base is a two/three-dimensional zone
three
The vitreous base extends approximately from ___mm anterior to the ora serrata to ___mm posterior to the ora serrata, and it is several mm thick.
a. 3, 2
b. 2, 2
c. 2, 3
d. 3, 3
c. 2, 3
The collagen fibrils are especially densely packed in this region
The vitreoretinal interface is the _inner/outer part of the cortex, which includes the internal limiting membrane (ILM) of the cornea/retina and anchoring fibrils of the conjunctiva/vitreous body.
outer, retina, vitreous
The ILM is a retinal structure between ___ and ___ µm thick, consisting mainly of type ___ collagen and proteoglycans. It contains several layers and can be considered the basal lamina of the ____ cells.
a. 1, 2, IV, Tarsal
b. 1, 3, IV, Mueller
c. 2, 3, III, Mueller
d. 1, 2, III, Tarsal
b. 1, 3, IV, Mueller
The vitreous cortex is firmly attached to the ILM at:
a. the vitreous base
b. Around the optic disc (Weiss ring)
c. the vessels
d. In the area surrounding the foveola at diameter of 500 µm
e. none of the above
f. all of the above except e
f. all of the above except e
a. the vitreous base
b. Around the optic disc (Weiss ring)
c. the vessels
d. In the area surrounding the foveola
Clinically important information; you must know!
T/F The aging process of the vitreoretinal interface has been studied with HVF in 209 healthy subjects.
False, OCT not HVF
In the OCT studies, preretinal strands, presumably posterior cortex, were found in _50% / 60% / 70% _of these nonsymptomatic cases with/without biomicroscopic evidence of posterior vitreous detachment (PVD).
60%, without
Blood vs Vitreous
Blood Conc. Vitreous Conc
Ascorbate 1.3 mg/100ml 7.6 mg/100ml
Bicarbonate 27 mmol/liter 25 mmol/liter
GAGs none 25 mg/100ml
Protein 7.3 mg/100ml 55 mg/100ml
Sodium 150 mmol/liter 137 mmol/liter
Potassium 105 mmol/liter 3.8 mmol/liter
Glucose 98 mg/100ml 50mg/100 ml
Vitreous lecture Slide 16
Blood Vs Vitreous Comparison
T/F The gel structure in the vitreous acts as a barrier against movement of solutes.
True
In the vitreous, substances may move by two different processes:
a. diffusion or bulk flow.
b. diffusion or osmosis
a. diffusion or bulk flow.
For diffusion in the vitreous, Fluorescein can/cannot be used as a tracer substance.
can
Bulk flow in the vitreous is/is not a result of a pressure gradient from the anterior to posterior pole of the eye.
IS
Large, high molecular weight substances move due to this gradient
Large, high molecular weight substances move due to _____ in the vitreous.
a. diffusion
b. osmosis
c. bulk flow
c. bulk flow
Bulk flow does/does not play any significant role for distribution of low molecular weight substances in the vitreous.
does NOT
T/F The vitreous body does not go through considerable physiological changes during life.
False. DOES go through changes that have great significance for its function.
The main aging change in the vitreous is a disintegration/formation of the gel structure, the so-called liquefaction or synchysis, especially notable in the periphery/center of the vitreous, where the collagen concentration is lowest/highest.
distengration, center, lowest
T/F The structure of the gel is dissolved and replaced with aqueous lacunae, which melt together over time.
True
Vitreous collagen molecular weight increases/decreases with age secondary to new covalent cross-links.
increases
T/F The aging vitreous collagen process is not equivalent to the aging process in collagen elsewhere in the body.
False, IS equivalent
Proteins are cross-linked because of the Maillard reaction, with the formation of a ionic/covalent bond between an amino group and a glucose leading to insoluble/soluble proteins.
covalent, insoluble
The vitreous glucose concentration is the same/doubled/tripled in persons with diabetes compared with that of healthy subjects.
doubled
The normal physiology of the vitreous body can be divided into three/four/five main groups.
four
- Support function for the retina and filling-up function of the vitreous body cavity
- Diffusion barrier between the anterior and the posterior segment of the eye
- Metabolic buffer function
- Establishment of an unhindered path of light
T/F The intact vitreous body protects the retina
True
An intact vitreous body, which fills up the half/entire vitreous cavity, may retard or prevent/induce or cause the development of a larger retinal detachment.
entire, retard or prevent
The vitreous body can absorb external forces and reduce/increase mechanical deformation of the eye globe.
reduce
T/F The intact vitreous body does not support the lens during trauma to the eye.
False, DOES support the eye
The eyes in which the vitreous has been removed during vitrectomy can/cannot have a normal function, and the retina is not/is detached.
can, is not
Posterior Vitreous Detachment (PVD) is when the central/peripheral degeneration is small/large and causes a collapse where the cortex sinks to the center/periphery of the vitreous body.
central, large, center
PVD is the least/most common pathophysiologic condition of the vitreous body/lens body and is considered a abnormal/normal physiologic aging phenomenon.
most, vitreous body, normal
Retinal tear can result if there is a weak/strong attachment between anterior/posterior cortex and the ILM.
strong, posterior
Retinal tear caused by a PVD is the 1st/2nd/3rd step in a rhegamatogenous retinal detachment.
1st
T/F PVD can induce traction on the retina, especially in the foveal region.
True
Under normal conditions, the blood-retinal barrier is tight/loose (low passive permeability).
tight
An increase/decrease in the passive permeability or a increase/decrease in the outward active transport may lead to edema formation.
increase, decrease
T/F In several studies, eyes with otherwise untreatable edema have been shown to have partial PVD and vitrectomy seems to improve visual acuity in these eyes.
True
However, vitrectomy has also been helpful in cases without evidence of vitreomacular traction.
Substances liberated from the anterior segment have difficulties reaching low/high concentrations in the anterior/posterior part of the eye
high, posterior
T/F The vitreous gel does not prevent topically administered substances from reaching the retina and optic nerve.
False, DOES prevent
If the vitreous body is partly removed, exchange between the anterior and posterior part of the eye is much _faster and easier/ slower and more difficult. _.
faster and slower
This is the case when the lens is removed and anterior vitrectomy has been performed
The preretinal oxygen tension is improved/worsened in diabetic patients after vitrectomy, indicating oxygen transport increases/decreases with faster fluid currents.
improved, increases
This is of clinical relevance because retinal neovascularization and macular edema regress
The vitreous can act as a metabolic buffer and a reservoir for metabolism of the ________ and ________.
a. ciliary body and cornea
b. cornea and retiina
c. ciliary body and the retina.
c. ciliary body and the retina.
T/F Glucose and glycogen in the vitreous body can supplement the metabolism of the retina, especially during anoxic conditions.
True
Vitamin C is also present in the vitreous body in relative low/high concentrations, where it can act as a reservoir of antioxidants in non-stress/stress situations, protecting the retina from metabolic- and light-induced free radicals.
high, stress
T/F Because normal function of the retina can be obtained after total vitrectomy, the metabolic buffer functions of the vitreous do seem to play an important role.
False, vitreous DOES NOT play an important role
Substances present in or produced in the retina are thus diluted by diffusing into the _____ body.
a. ciliary
b. corneal
c. vitreous
d. retinal
c. vitreous
The pre-retinal concentration of retinally produced vasoproliferation depends/independent on the condition of the vitreous body.
depends
T/F If the vitreous acts as a diffusion barrier to substances, they are retained in high concentrations close to the retina.
True
One could assume a vitrectomy can/cannot cure conditions such as diabetic retinopathy.
can
A vitrectomy can also cause/prevent the vasoproliferative factors to move from the posterior to the anterior pole leading to neovascularization in the anterior/posterior segment. (neovascular glaucoma)
cause, posterior
An important function for the vitreous body is to maintain optimal opaqueness/transparency, which is primarily produced by the low/high concentration of structural macromolecules.
transparency, low
T/F Degeneration of the vitreous with generation of opacities interferes with the path of light.
True
What is/are other names for vitreous opacities?
a. floaters
b. muches volantes
c. none of the above
d. a and b
d. a and b
a. floaters
b. muches volantes
What is/are pathological conditions that interfere with vitreous transparency?
a. Synchysis scintillations
b. Asteroid degeneration
c, Hemorrhages
d. Inflammatory material
e. Fibrous tissue
f. Lack of regression of the hyaloid artery
g. all of the above, except h
h. none of the aboveg. all of the above, except h
a. Synchysis scintillations
b. Asteroid degeneration
c, Hemorrhages
d. Inflammatory material
e. Fibrous tissue
f. Lack of regression of the hyaloid artery
T/F Although the vitreous body can be removed and almost normal function of the eye will still be maintained, the vitreous body plays an important role in the physiology and pathophysiology of the eye.
True
KNOW this, he repeated this statement in several slides!!!
