Ocular: Aqueous Compartment Flashcards
What separates the posterior and anterior chambers?
Iris
Aqueous humor flow is ______.
Unidirectional
The posterior and anterior chambers are filled with what?
Aqueous humor
What is aqueous humor?
Clear fluid that pressurizes the eye
The aqueous humor provides nutrients to what a vascular structures?
-lens
-cornea
-trabecular mesh work
Aqueous humor is produced by…
The ciliary body
How does the aqueous humor exit the eye?
The iridocorneal angle
What prevents backflow of the aqueous humor?
Tight junctions between the posterior pigment epithelium of iris
What is the approx. volume of the posterior chamber?
50 to 65 ul
What are the three compartments of the posterior chamber?(both names)
1.Retro-zonular (canal of petit)
2.Zonular (canal of Hanover)
3.Pre-zonular (posterior chamber proper)
What is the approx. volume of the anterior chamber?
200 to 250ul
What happens with the anterior chamber depth as we age? And why?
Decreases due to expansion of size of lens
3.6mm to 2.7mm
Which tunics fuse to form the iridocorneal angle
Uveal tunic and fibrous tunic
What structures form the anterior chamber angle?
Cornea and iris
Th longitudinal muscle of the ciliary muscle(uvea) attaches to…
The scleral spur(fibrous tunic)
What are the structures of the iridocorneal angle from infringer to superior
-Iris root
-Ciliary body band
-Scleral spur
-Trabecular mesh work
-Schwalbe’s line
For gonioscopy what are you looking for to see if the angle is open enough?
You are looking to see the trabecular mesh work
What is the total volume of the aqueous compartment?
250-315 microL
What is the rate that aqueous humor is secreted?
2.5ul/minutes
How long odes it take for the entire volume of the aqueous compartment to turnover?
100 mintues
Where is the iris root in relation to the anterior chamber angle?
-it inserts in the anterior face of the ciliary body
-literally in the corner of the angle
Unlike the ciliary body in the posterior chamber, the ciliary body band does not have what?
Epithelial lining
What is the widest band visible in the iridocorneal angle?
ciliary body band
Why does the CBB NOT have an epithelial lining?
To allow aqueous humor to pass through and continue to the uveoscleral pathway
What is the scleral spur?
An internal projection of sclera
What muscle attaches to the scleral spur?
Longitudinal bundle of ciliary muscle
What is the base of the trabecular mesh work?
The scleral spur
How does the trabecular meshwork change during ciliary body contraction?
Trabecular meshwork is open and more aqueous outflow goes to uveoscleral pathway
During what process are the TM spaces smaller and at their normal state?
During relaxation of the ciliary muscle
The trabecular meshwork sits within what structure?
Internal scleral sulcus
What is the filtration apparatus that provides the main resistance to keep the eye pressurized?
TM
The TM has what percentage of aqueous humor outflow?
90%
TM is the gate keeper for what structure?
Schlemm’s canal
In what condition is resistance to aqueous is too high?
Primary open angle glaucoma
Where does Schwab’s line terminate peripherally?
Descemet’s membrane
What is the most superior structure in the iridocorneal angle?
Schwalbe’s line
What is the normal appearance of SL? What is it called when it’s pigmented?
Normal: glossy and whitish
Pigmented: Sampolesi’s line
Where does 10% of the aqueous humor leave the eye?
Via iris root/ ciliary body band (uveoscleral route, unconventional pathway)
When outflow of aqueous humor is impeded the pressure in the eye will _____ and damage ____.
Increase, retinal ganglion cells
What are the possible causes of enhanced resistance to aqueous humor drainage through the TM
-Buildup of pigment, inflammatory cells, plaque-like material, excessive blood, or neovascularization within the TEM
-Chronic corticosteroid use
-Elevated Episcleral Venous Pressure (EVP)
-Narrow angles (especially hyperopes)
-Pupillary Dilation (mydriasis) in eye with narrow angle -Relative Pupillary Block
-Peripheral Anterior Synechiae
-Primary-Open Angle Glaucoma (?? Exact cause unknown).
What is relative pupillary block?
-resistance in AH flow from PC to AC which leads to increased pressure in PC that causes iris bowing and decreasing angle
What is laser iridomtomy?
Creation of a hole in the peripheral iris so the AH can flow better
What is surgical iredectomy?
Precursor to laser, sam process but cutting out a chunk
What is posterior synechiae?
Adhesions between post. Iris and ant. Lens due to inflammation
Why is the mid-dilated pupil a cause for concern>
Iris root is bunched up when dilated so it can impede flow to the TM
-high risk of contact between iris and lens
What is peripheral anterior synechia?
Ant. Surface of iris adherent to TM or corneal endothelium
-usually from inflammation
What is an iris process?
Thread-like strands of iris tissue that extend to TM
-NORMAL
What is the differnce between peripheral ant. Synechia and iris process?
Iris processes are normal, synechia are not
