Vitreous Flashcards
What is the largest ocular organ?
The vitreous
What is the vitreous in contact with?
Ciliary body, lens, retina
The vitreous is ____% water. In regards to state, it is also ___% gel and ___% liquid.
98.5% water
80% gel and 20% liquid
What type of collagen forms the sieve of the vitreous?
Type II
What do Halocytes do?
Phagocytes - synthesis of collagen and glycoprotein
What do Fibrocytes do?
Synthesize collagen
Together, Fibrocytes and glial cells form ___% of the cell population
10%
What do VEGF molecules do?
Induce vasculogenesis (formation of new blood vessels)
The primary vitreous occurs in the first _______ weeks of gestation. ______ cells enter through fetal fissure and form hyaloid vessels. ______ released by lens induces vasculogenesis. _____ and _____ form collagen.
The primary vitreous occurs 3-4 weeks gestation. Mesodermal cells enter through fetal fissure and form hyaloid vessels. VEGF release by lens induces vasculogenesis. fibroblasts and halocytes form collagen.
The secondary vitreous occurs around the ______ week of gestation. ________ factor present. _____ vessels retract. Then the ______ is formed.
The secondary vitreous occurs around the 6th week of gestation. Anti-angiogenesis factor present. Hyaloid vessels retract. Then the Vitreous body is formed.
What happens in the tertiary vitreous?
Formation of lens zonules
What are the four anatomical regions of the Vitreous?
- Cortex
- Base
- Patellar Fossa
- Canal of Cloquet
In the cortex of the vitreous, the average thickness is _______. There is no cortex over the ____ and it thins over the ______.
In the cortex of the vitreous, the average thickness is 200 micrometers. There is no cortex over the disc and it thins over the macula.
The vitreous base is attached to the _______. It has a ______ broad annular region and is attached to the _______. While it has strong _______ fibers, it has weak _____ fibers.
The vitreous base is attached to the pars plana. It has a 1.5 mm broad annular region and is attached to the inner limiting membrane. While it has strong perpendicular fibers, it has weak radial fibers.
The Patellar Fossa can be located at the _____ and is associated with the _______ and the ______.
The Patellar Fossa can be located at the posterior surface of lens and is associated with the retrolental space of Berger and the Ligament of Wieger.
What is the pneumonic to remember the vitreous attachments?
Big - Vitreous Base Lions - Ligament of Wieger Often - Optic Nerve Pick - Peripheral Attachment Fights - Fovea
Where is the ECM “glue” in the eye?
Between the internal limiting membrane and the posterior vitreous
What happens to the vitreous as you age? (in regards to liquidation)
At birth, the vitreous is completely gel. As we age, the vitreous slowly turns to liquid. At age 65, it is 60% liquid.
What is synchisis?
Vitreous liquification
What is syneresis?
Vitreous collapse
What is a Signet Ring Floater? (Weiss ring)
Detachment at the Optic Nerve. Creates a “floater” 20 degrees in the temporal visual field.
What happens in Posterior Vitreal Detachment (PVD)?
The cortical vitreous separates from the inner limiting layer of the retina due to the formation of “lakes” in the vitreous.
The sequence of events of PVD is:
- ______
- Hole develops in the _______
- Vitreal fluid passes into the _______
- Detaches vitreous from the _____ of retina
- Spreads to posterior border of ______
The sequence of events of PVD is:
- synchysis
- Hole develops in the posterior vitreal cortex
- Vitreal fluid passes into the retrohyaloid space
- Detaches vitreous from the ILM of retina
- Spreads to posterior border of vitreous base
What is characteristic of a Weiss Ring?
Ring shaped opacity
