Anatomy of Anterior Chamber Angle Structures

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Questions and Answers

What is the location of the scleral spur?

At the anterior edge of the internal scleral sulcus

At the posterior edge of the internal scleral sulcus (correct)

At the internal scleral sulcus

At the corneoscleral junction

What is the function of the trabecular meshwork and Schlemm's canal?

Formation of the corneoscleral junction

Filtration of aqueous humor (correct)

Support of the longitudinal ciliary muscle fibers

Regulation of aqueous humor production

What is the term for the system of fine fibrils connecting the cribriform plexus to the inner wall endothelium and the plaque material?

Trabecular sheets

Connecting fibrils (correct)

Ciliary muscle tendons

Elastic-like fibers

What is the orientation of the elastic-like fibers of the trabecular lamellas?

Equatorial Signup and view all the answers

What is the region where the ciliary muscle tendons attach?

Posterior portion of the internal scleral sulcus Signup and view all the answers

What is the layer where the cribriform plexus is mainly located?

Region between the first and second subendothelial cell layers Signup and view all the answers

What is the main component of the limbal stroma?

Scleral and corneal tissues Signup and view all the answers

What is the function of the vessels forming the intrascleral plexus?

To drain aqueous humor from the eye Signup and view all the answers

What is the term for the spaces between the trabecular meshwork sheets?

Intertrabecular spaces Signup and view all the answers

Which part of the trabecular meshwork has the smallest pores?

Juxtacanalicular meshwork Signup and view all the answers

What is the purpose of the ciliary muscle tendons?

To connect the ciliary muscle to the trabecular meshwork Signup and view all the answers

What is the term for the termination of Descemet's membrane?

Schwalbe's line Signup and view all the answers

What is the main component of Tenon's capsule?

Loose connective tissue Signup and view all the answers

What is the function of the conjunctival stromal vessels?

To form the peripheral corneal arcades Signup and view all the answers

What is the term for the region of the trabecular meshwork that attaches to the scleral spur?

Corneoscleral meshwork Signup and view all the answers

What is the purpose of the iris process?

To connect the iris to the trabecular meshwork Signup and view all the answers

What is the main function of the canal of Schlemm?

To drain aqueous humor from the eye Signup and view all the answers

What type of fibers are found in the juxtacanalicular connective tissue region?

Collagen and elastic-like fibers Signup and view all the answers

What is the purpose of the aqueous humor flow pathway?

To regulate intraocular pressure Signup and view all the answers

What percentage of aqueous humor flows through the uveal meshwork?

5-35% Signup and view all the answers

What is the term for the spaces within the uveal meshwork?

Large-size pores Signup and view all the answers

What is the name of the vessels that drain directly into the episcleral veins?

Aqueous veins of Ascher Signup and view all the answers

What is the purpose of the giant vacuoles in the endothelial cells lining the canal of Schlemm?

To facilitate passive diffusion Signup and view all the answers

What is the name of the structure that separates the endothelial cell lining of the canal of Schlemm from the trabecular meshwork?

Juxtacanalicular connective tissue region Signup and view all the answers

What is the name of the space that exists between the iris and lens?

Posterior chamber Signup and view all the answers

What is the main route of aqueous humor outflow from the anterior chamber?

Through the trabecular meshwork and Schlemm's canal Signup and view all the answers

What is the main function of the aqueous humor?

To carry away waste products of the lens and cornea Signup and view all the answers

What is the normal resistance to aqueous passage through the trabecular meshwork?

Low resistance Signup and view all the answers

Where is the location of higher resistance to aqueous movement?

Juxtacanalicular tissue and endothelium of the inner wall of Schlemm's canal Signup and view all the answers

What percentage of the outflow resistance is at the juxtacanalicular tissue?

75% Signup and view all the answers

What is the average intraocular pressure (IOP)?

15.5 mmHg Signup and view all the answers

What is the effect of diabetes on the eye?

Neovascularization from proliferative diabetic retinopathy Signup and view all the answers

What is the effect of uveitis on the eye?

Inflammation of the uveal tract Signup and view all the answers

What is the effect of Fuch's endothelial dystrophy on the eye?

Chronic dystrophy leading to permanent damage to the trabecular meshwork Signup and view all the answers

What is the effect of pseudoexfoliative glaucoma on the eye?

Aging epithelial cells of the iris and lens capsule releasing pigment and pseudoexfoliative material Signup and view all the answers

What is the effect of pigment dispersion glaucoma on the eye?

Pigment liberated from the posterior layer of the iris causing damage to the trabecular fibrils Signup and view all the answers

Study Notes

Anterior Chamber Angle Structures

Located at the internal scleral sulcus (corneoscleral junction)
Consists of:
- Trabecular Meshwork
- Schlemm’s canal (both part of the filtration apparatus)
- Scleral spur

Scleral Spur

Lies at the posterior edge of the internal scleral sulcus
Posterior portion: longitudinal ciliary muscle fibers attach
Anterior portion: many trabecular sheets attach

Trabecular Meshwork

Occupies most of the inner aspect of the internal scleral sulcus
Triangular shape: apex at Schwalbe’s line (termination of Descemet’s membrane), base at the scleral spur
Composed of:
- Flattened, perforated sheets of collagen and elastic fibers embedded in ground substance
- Covered by basement membrane and endothelium
3-5 sheets at the apex, branching into 15-20 sheets posteriorly
Intertrabecular spaces between the sheets connected through pores (“spaces of Fontana”)
Divided into three anatomic divisions:
1. Uvealmeshwork (inner sheets attaching to ciliary stroma and longitudinal muscle fibers)
2. Corneoscleralmeshwork (outer region attaching to the scleral spur)
3. Juxtacanalicularmeshwork (connective tissue surrounded by endothelium)

Schlemm's Canal

Circular vessel considered to be a venous channel (contains aqueous humor instead of blood)
Lumen lined with endothelial cells joined by zonula occludens

Aqueous Humor Dynamics

Produced in the pars plicata of the ciliary body
Secreted to the posterior chamber through the non-pigmented ciliary epithelium
Passes between the iris and lens, entering the anterior chamber through the pupil
Circulates in convection currents in the anterior chamber
Exits through the periphery of the chamber
Two main exit routes:
1. Unconventional outflow (5-35%): through the spaces within the uveal meshwork, into connective tissue spaces surrounding the ciliary body muscle bundles, and absorbed into the sclera or anterior ciliary veins
2. Conventional outflow pathway: through the uveal meshwork, corneoscleral meshwork, and juxtacanalicular tissue, entering Schlemm's canal

Aqueous Humor Outflow

Regulated by the balance between production and exit
Maintained within a small range by the complex equilibrium between production and exit
Most cases of increased IOP are caused by decreased aqueous outflow
Resistance to aqueous outflow located in the juxtacanalicular tissue (JCT) and the endothelium of the inner wall of Schlemm's canal

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Description

Learn about the structures located at the internal scleral sulcus, including the Trabecular Meshwork, Schlemm's canal, and Scleral spur. Understand their functions and relationships in the filtration apparatus.