Glaucoma Qs And As Flashcards
A condition of increased pressure within the eye, causing gradual loss of sight
Glaucoma
Various ways that IOP can get elevated within the eye
- aqueous humor production rate
- TM outflow interference (open vs closed)
- pupillary block
- plateau iris
- pigmentation dispersions
- neo vascularization
- injury
- meds
- tumors
What are the different types of glaucoma
- primary open angle
- narrow angle
- secondary
Where doe aqueous humor get produced
NPCE of the ciliary body, pars plicata
Where does aqueous humor go
From posterior chamber, through the pupils, into the anterior chamber
How does aqueous humor production rate affect IOP
Not enough, low pressure. Too much, high pressure
What forms the blood aqueous barrier
Tight junctions of NPE
Can control how much fluid goes through them
What happens if thi sbarrier begins to breaks down
- protein from stroma get into posterior chamber, inflammatory cells
- consequences on the pressure of the eye
- this can increase aqueous production
- gate keepers broken down so everything can get out and back in
If the anatomical angle is wide open, could there still be an issue with TM outflow
Yes from pigmentary dispersion
How can the TM outflow be affected if the angle is open
- pigmentation dispersion
- plaque in JCT
- Synchiea
- proteins that get through a broken down tight junction of ciliary body
How would we treat a blocked angle
- shunts/blebs
- Laser trabeculoplasty (shrinks tissue and increases outflow)
Increased resistance to flow of aqueous humor through the pupil from the posterior to anterior chamber, this leads to an anterior bowing of the peripheral iris over the TM and it causes the angle to close
Pupillary block
What is the normal iris to lens relationship in the eye
Iris is anterior to the lens and touches it with the lens on its posterior side (of iris), acts as a one way valve to allow fluid to get out of the posterior chamber, but not back in
What is the normal flow of aqueous through this relationship of lens and iris
-iris acts as a one way valve that allows the aqueous to flow in one direction from posterior to anterior, and prevents it from flowing back into the posteiror chamber
Where does the pupillary block occur
Pupil gets pushed against the lens, block the flow from posterior chamber causing a buildup of pressure in the posterior chamber, and causing the angle to get narrow or close
How will pupillary block affect the iris morphology
Iris can get stuck with inflammation sticky stuff and can cause the iris to stick to the anterior surface of the lens and fluid cannot pass through it anymore
- iris will bulge anteriorly
- middle to peripheral part of iris bows
How does pupillary block affect aqueous flow in the posterior and anterior chamber
Aqueous gets stuck in the posteiror chamber, causes IOP to rise, and angle to close/get narrow
-pressure goes up
How do you treat pupillary block
Laser peripheral iridotomy
One of the most common angle closure glaucomas presenting in young patients. Closing of the anterior chamber angle secondary to a large or anteriorly positioned ciliary body that mechanically alters the postion of the peripheral iris in relation to the TM
Plateau iris
Which is acquired, pupillary block or plateau iris
Pupillary block
Which are you born with, pupillary block, plateau iris
Plateau iris
The iris base in plateau iris
Seems to reach back and connect to ciliary body. Normally would attach laterally
How do we treat plateau iris
-pilocarpine (PNS mimetic) Peripheral iridotomy (more as a prophylactic measure
Affliction of the eye that can lead to a form of glaucoma known as pigmentary glaucoma. It takes place when the pigment cells slough off from the back of the iris and float around in the aqueous
Pigmentary dispersion syndrome (PDS)
Where does the pigmentary dispersion end up and what effect does it have?
- TM and it blocks the flow of aqueous
- causes increase in IOP
- transillumination defect (TID)
How do you treat pigmentary dispersion
- peripheral iridotomy
- laser trabeculoplasty to shrink tissue
- possibly use medication to lower IOP
If you see pigment stuck to the back of the cornea
- Kruckenburg spindle
- you need to test for glaucoma
- the pigment is from the posterior cornea
- high risk for pigmentary glaucoma
Does the pigment in Krukenburg spindle always orient vertical on back of cornea?
Convective flow of aqueous and the temperature of the aqueous being warmer in the back causing it to fall in the front
-aqueous rises along the anterior border of the iris and then falls along the cornea because it is cooler tissue
Why is the pigment only in the center of the posterior cornea
Cells will gravitate to the light, pigment accumulates here, also curvature of cornea
Medical condition of the iris which new abnormal blood vessels are found on the surface of the iris
Neovascularization of the iris (NVI) or Rubeosis iridis
What causes NVI
Lack of oxygen
- blocked blood vessel (CRA)
- diabetes
What complications can arise from NVI
- leaking of fluid into the anterior and posterior chamber
- increased IOP
- blood vessels could grow into the angle too, narrow the angle
Treatment for NVI
- AntiVEGF
- steroids
- laser
Perfusion theory of increased IOP
- the higher the pressure, the Ig her the gradient the blood has to get into the eye and the nerve
- measure ocular perfusion pressure
- the higher the gradient, the bigger the problem
- causes slow ischemia over time
Physical damage from increased IOP
High pressure crimping the nerves as they bend at 90 degrees
