anatomy of anterior chamber of eye

anatomy of anterior chamber of eye

1. ANGLE OF ANTERIOR CHAMBER

2. ANTERIOR CHAMBER Boundary: Anteriorly--- - posterior surface of cornea Posteriorly ---- Iris diaphragm and the pupil.

3. Depth---3mm deep Volume--0.25 ml of aqueous Shallower in the hypermetropic than the myopic eye, in children & old people Depth decreases by 0.01 mm/year of life.

4. Depth is slightly diminished during--- accommodation, increased lens curvature & forward translocation of lens. Deepens by 0.06 mm for each diopter of myopia.

5. Structures in the anterior chamber Schawlbe line. Schlemm canal and t rabecular meshwork. Scleral spur. Anterio r border of the ciliary body. Peripheral iris

6. Development By 7th week---mesenchymal cells develop trabecular meshwork. Iris-----from advancing bilayered optic cup. At 15th week---Corneal endothelium meets derivative of iris to demarcate the angle. Angle deepening continues even after birth.

7. Schwalbe's line A fine scalloped anterior border which represents termination of descemet's membrane. Contains circularly arranged collagen fibers intermixed with elastic tissue. Seen as glistening white line in gonioscopy.

8. Schwalbe's line marks transition from ------- ★Trabecular to corneal endothelium. ★Termination of descemet's membrane. ★Insertion of trabecular meshwork into corneal stroma.

9. Trabecular meshwork A spongework or sieve like structure made up of connective tissue lined by trabeculocytes , which have contractile & phagocytic properties. Approximately 750 um in width which covers the internal aspect of schlemm's canal. Its main function is in drainage of aquous humour .

10. Roughly triangular in cross section. Apex -- schwalbe's line. Base -- scleral spur & cilliary body .

11. It is morphologically & functionally divided into 3 types :1)Uveal meshwork 2)Corneoscleral meshwork. 3)Juxtacanalicular tissue/meshwork.

12. 1.Uveal Meshwork Innermost part (1-2 layers)of TM. Comprises of trabecular bands, which have a central core that mainly consists of collagenous fibres distributed with a few elastic fibers. Lined by trabecular endothelial cells resting on a thick basement membrane.

13. . The trabecular bands run mostly in radial fashion which interlace & taper anteriorly. . Trabecular apertures size is 25-75 um . . The trabeculocytes usually contain pigment granules.

14. 2. The Corneoscleral Meshwork . Consists of a series of thin,flat , perforated connective tissue sheets arranged in a laminar pattern in the mid portion. . The central core consists of collagenous & elastic fibers.

15. Each trabecular beam is covered by a monolayer of trabecular endothelial cells, supported by basement membrane . The pore size is smaller than the uveal meshwork (5-50 um).

16. 3. Juxtacanalicular meshwork Also known as cribriform meshwork. The outermost part of TM. Lies adjacent to the inner wall of schlemm's canal. Less cellular than its trabecular counterpart & shows a compact arrangement of fibrocytic cells.

17. This zone is occupied mainly by an irregular but dense arrangement of collagen & elastic tissue. It has important phagocytic & secretory properties to the self cleansing role of meshwork. Makes a major contribution to outflow resistance not only because the pathways are narrow & tortous but also presence of extracellular proteoglycans & glycoprotein.

18. Schlemm's canal A narrow circular tube, some 36 mm in circumference in the outer portion of internal scleral sulcus. Lined by a single layer of spindle shaped endothelial cells, oriented parallel to its circumference. Conducts aquous humour flow from the trabecular region to the episcleral venous network via the collector channels.

19. Continued.... Schlemm's canal has two walls--- Inner wall & Outer wall.

20. Inner wall of schlemm's canal Endothelial lining of canal consists of a complete monolayer of flat endothelial cells that don’t rest on a complete basement membrane. Lateral wall is joined by tight junctions.

21. The most prominent features of the inner wall of schlemm's canal are the giant vacuoles. These are invaginations which are generally globular in profile on meridional sections.

22. The endothelial lining is single layered with a well developed basement membrane. These cells are longer, flatter,& smoother in outline. Outer wall of schlemm's canal

23. Endothelial cells are joined by zonulae occludentes . Rest on a basal lamina which is thicker & more continuous than that on trabecular side.

24. Collector channels Schlemm's canal is connected to episcleral & conjunctival veins by a complex system of intrascleral channels. They arise at irregular intervals from the outer wall of schlemm's canal.

25. They are 25-35 in num & drain into 3 interconnecting venous plexus-----deep, mid scleral & episcleral venous plexus. There are no valves present in these system.

26. Episcleral & conjunctival veins Most aqueous vessel are directed posteriorly with most of these drains into episcleral veins. A few crosses the subconjunctival tissue & drain into conjunctival veins

27. The Episcleral vein ⬇️ Anterior cilliary & superior ophthalmic vein ⬇️ Cavernous sinus.

28. Conjunctival vein ⬇️ Palpebral & angular vein ⬇️ Superior ophthalmic vein

29. Scleral spur wedge shaped circular ridge. Pale,translucent narrow strip of scleral tissue. Composed of circularly arranged collagen & elastic fibers.

30. Attachment Anteriorly : trabecular meshwork. Posteriorly : Sclera & anterior tendons of longitudinal cilliary muscle.

31. Contraction of longitudinal cilliary muscle opens up trabecular spaces. Scleral spur prevents cilliary muscle from causing schlemm's canal to collapse.

32. Cilliary band Marks the posterior most part of angle as a dark cilliary band Represents the anetrior face of cilliary body including the insertion of cilliary muscle into the scleral spur. Wide in myopes. Narrow in hypermetropes .

33. Innervation supraciliary nerve plexus & the cilliary plexus in the region of the scleral spur. Both myelinated & non myelinated nerve fibers have been demostrated here. Myelinated nerve fibers are most commonly found towards the posterior attachment of trabecular sheet.

34. Diagnostic modalities Van harick test: comparing the depth of peripheral anterior chamber to the thickness of cornea using a narrow beam within the limbus at a 60° angle. Gonioscopy.

35. Flashlight/ Pentorch test: evaluated by focusing a beam of light on temporal limbus, parallel to the surface of iris.

36. Gonioscopy: evaluation of structures by using a special lens( goniolens ) & slit lamp biomicroscope.

37. Importance of angle of anterior chamber For classification of glaucoma. To assess traumatic glaucoma. To assess angle recession. For planning of treatment.

38. ... ... Thank you.