L25 - Anterior & Posterior Compartments Flashcards
(42 cards)
What are the three chambers of the globe?
Anterior chamber, posterior chamber, vitreous body.
What is the hyaloid canal?
A channel running through the vitreous body.
Where is the posterior chamber located and what are its boundaries?
Annular area behind the iris; bounded by the posterior iris surface, equatorial zone of the lens, anterior face of the vitreous, and the ciliary body.
What projects into the posterior chamber and what is their function?
Ciliary processes, which secrete aqueous humor.
Where do the zonular fibers arise and where do they insert?
Arise from the internal limiting membrane of the nonpigmented epithelium of the ciliary body, pass through the posterior chamber, and insert into the lens capsule.
What are the boundaries of the anterior chamber?
Cornea and iris.
What are the primary functions of Schlemm’s canal and the trabecular meshwork (TM)?
To provide an exit for aqueous humor and allow nutrient diffusion to nearby deep limbal and scleral tissue.
What are the two main functions of the anterior chamber?
Aqueous humor dynamics and nourishing surrounding tissues.
What are the clinical parameters of the anterior chamber?
Anterior chamber depth (ACD) and anterior chamber angle (ACA).
What are typical anterior chamber dimensions?
Depth: 3.15 mm (range 2.6 to 4.4 mm), diameter: 11.3 to 12.4 mm, volume: 220 μl, angle: 20 to 45°.
What forms the anterior chamber angle (ACA)?
Formed between the posterior surface of the cornea and anterior surface of the iris.
What are the structures bounding the ACA (from anterior to posterior)?
Schwalbe’s line, trabecular meshwork, scleral spur, anterior surface of ciliary body, root of iris.
What are the main structures seen in the ACA?
Schwalbe’s line, trabecular meshwork, Schlemm’s canal, scleral spur, ciliary muscle (meridional portion).
What is the clinical grading of the ACA and its significance?
Grade 4 (35˚-45˚): Ciliary body band seen, incapable of closure
Grade 3 (25˚-35˚): Scleral spur seen, incapable of closure
Grade 2 (20˚): Trabecular meshwork seen, closure possible but unlikely
Grade 1 (10˚): Schwalbe’s line seen, high risk of closure
Grade S (<10˚): No iridocorneal contact, imminent closure
Grade O (0˚): No corneal wedge, indentation gonioscopy.
What is Schwalbe’s line?
Anterior to the apical portion of the trabecular meshwork, marks the transition from trabecular to corneal endothelium, termination of Descemet’s membrane, and insertion of trabecular meshwork into corneal stroma.
What is the trabecular meshwork (TM)?
Spongy, sieve-like tissue, roughly triangular, bordered anteriorly by cornea and posteriorly by scleral spur and ciliary body; divided into uveal meshwork, corneoscleral meshwork, and juxtacanalicular tissue.
Describe the uveal meshwork.
Innermost portion, adjacent to aqueous humor, arranged in cord/rope-like trabeculae from iris root to Schwalbe’s line, with irregular openings (25–75 μm).
Describe the corneoscleral meshwork.
Extends from Schwalbe’s line to scleral spur, contains 8–14 sheets of trabeculae with elliptical openings (5–50 μm), openings become smaller toward Schlemm’s canal.
What is the function of the corneoscleral meshwork in IOP regulation?
Tension between openings regulates baseline IOP; increased IOP increases tension and drainage.
Describe the juxtacanalicular tissue.
Outermost portion, adjacent to Schlemm’s canal, consists of pore tissue, cribriform layer, and endothelial meshwork with three layers: inner trabecular endothelial, central connective tissue, and endothelium of Schlemm’s canal.
What is the structure and function of Schlemm’s canal?
360° endothelial-lined channel, 190–370 μm in diameter, continuous with inner wall endothelium, has numerous collector channels, drains into intrascleral, episcleral, subconjunctival venous plexus, and aqueous veins.
What is the composition of aqueous humor?
Clear, colorless fluid; 0.31 ml volume, pH 7.2, 99.9% water, low protein, glucose (75% plasma concentration), electrolytes, high ascorbic acid.
What are the functions of aqueous humor?
Brings oxygen/nutrients to lens, cornea, iris; removes metabolic waste; provides optically clear medium; maintains IOP; protects against UV-induced oxidative products; facilitates immune responses.
Where is aqueous humor produced and how does it drain?
Produced by ciliary body in posterior chamber; drains primarily via trabecular meshwork (conventional, 70–95%) and secondarily via uveoscleral and uveovortex outflow (5–30%).
