Anatomy of uvea UVEA of ophthalmology.pptx

Uvea anatomy and embryology with physiology slides. It also contains images and clinical vignette.

1. ANATOMY UVEA AND CLINICAL CORELATION PRESENTED BY; DR. NIGI SHRESTHA 1 ST YEAR RESIDENT DEPT. OPHTHALMOLOGY

2. LAYOUT INTRODUCTION EMBRYOLOGY ANATOMY IRIS CILIARY BODY CHOROID BLOOD SUPPLY (ARTERIAL AND VENOUS SUPPLY)

3. INTRODUCTION Vascular coat of the eye, between the sclera and the neuroepithelium Uvea: derived from Greek word ‘ uva ’ , means grape It consists of the Iris ciliary body choroid.

4. EMBRYOLOGY IRIS Both the layers of epithelium are derived from the marginal region of optic cup(Neuroectoderm) Sphincter and dilator derived from anterior epithelium Stroma and vessels: mesoderm

5. CILIARY BODY Proximal region of optic cup neuroectoderm which undergoes convulation to form ciliary process(70-75) CHOROID Vascular endothelium and the haemopoietic cells of choroid : Endoderm Choroidal stroma ( vascular pericytes, smooth muscles, melanocytes and collagenous components) : Ectoderm

6. MILESTONES

7. CONGENITAL ANOMALIES

8. UVEAL COLOBOMA Failure of embryonic fissure to close in 5th week gestation Typical coloboma : Located inferonasally in the region of closure of embryonic fissure Complete coloboma : Extends from pupil to optic nerve Includes retina, choroid, ciliary body, iris Incomplete coloboma : Involve the iris alone, or iris and ciliary body, or iris, ciliary body and part of choroid Atypical coloboma - Occasionally found in other positions i.e. not related to fissure closure - It is usually incomplete

9. ANATOMY IRIS anterior portion of the uveal tract forms a diaphragm in front of the crystalline lens 12 mm in diameter and about 37 to 38 mm in circumference thickest at its central portion (the collarette) thinnest near the ciliary body's insertion point (the root): the site most prone to tears from trauma( Iridodialysis )

10. In the center (slightly nasally, inferiorly), apperature of about 2-3mm in present The pupillary margin rests slightly on the anterior surface of the lens- lies in a plane anterior to the iris root- Anteriorly, the iris is bathed by aqueous humor. Posteriorly, the central portion of the iris leans on the lens- displaces the iris anteriorly -results in its characteristic conical configuration

11. The color of the iris is determined by three main variables the density and structure of the iris stroma the pigment epithelium the pigment content (granules) within the melanocytes of the iris stroma

12. MACROSCOPIC APPERANCE ANTERIOR SURFACE collarette of the iris is located about 1.5 mm from the pupillary margin Overlies incomplete vascular circle (circulus vasculosus iridis minor ) divides the iris into two zones pupillary zone the ciliary zone

13. POSTERIOR SURFACE Dark brown and smooth and displays the following radial and circular furrows contraction folds of Schwalbe structural folds of Schwalbe Circular contraction furrows are also present

14. MICROSCOPIC STRUCTURE The layers of the iris from anterior to posterior are: Anterior border layer/ anterior limiting layer Stroma and sphincter muscle Anterior epithelium and dilator muscle Posterior pigmented epithelium

15. Anterior limiting layer Anterior most condensed part of stroma Contains the melanocytes and fibroblasts Deficient in areas of crypts and thin at region of contraction furrows Definitive colour of iris depends on this layer

16. Stroma The stroma consists of a loose collagenous network with mucopolysaccharide ground substances Consist of : The sphincter pupillae muscle Dilator pupillae muscles The vessels and nerves of the iris Cellular elements: fibroblasts, melanocytes, clump cells and mast cells

17. Sphincter pupillae muscle Oriented parallel to the pupillary margin Measure 0.75mm in diameter and has thickness of 0.1-1.7mm Contractions causes constriction (Miosis) Supplied by parasympathetic nerve(through 3 rd nerve)

18. Dilator pupillae muscle 4ųm in thickness Located in ciliary zone Oriented radially from iris root toward the pupil Contraction cause- dilatation of pupil Supplied by sympathetic nerve

19. Vessels form bulk of stroma branches of circulous arteriosis major major peculiarities- absence of Internal elastic lamina and non fenestrated capillary endothelium Pigment cells- melanocytes Lymphocytes, fibroblast and macrophages

20. Anterior epithelium anterior continuation of pigment epithelium of retina and ciliary body Lacks melanocytes Continues anteriorly : pupillary margin as cuboidal epithelial cells Posteriorly : pigmented epithelial cells of ciliary body Basal processes- give rise to dilator pupilla

21. Posterior pigmented epithelial layer Single layer of heavily pigmented simple columnar cells At posterior, continuous with inner non-pigmented epithelial layer of ciliary body Curled to anterior surface at pupil margin – pupillary ruff

22. FUNCTIONS OF IRIS Controls amount of light entering the eye through pupil Defines eye colour Source of blood ocular tissue

23. CLINICAL SIGNIFICANCE Ectropion uveae presence of iris pigment epithelium on anterior surface of iris Congenital or a/w rubeosis irides , neurofibromatosis,etc Iris Nodules Accumulated deposits of epithelioid cells and lymphocytes deposited onto the iris without tissue destruction . Irish atrophy

24. CILIARY BODY It extends from the posterior limit of limbus ( scleral spur and iris root) to Ora serrata Its is triangular shape in cross section- base facing anterior chamber and apex at ora serrata Dimension- 7mm wide temporally -6mm nasally (from limbus)

25. It consists two parts Pars plicata-2mm- Anterior vascular part Pars plana- 4mm- Posterior flat avascular part Avascular pars plana is located 3-4mm from the corneal limbus which is the safest posterior surgical approach to the vitreous cavity Function Aqueous humor production Lens accomodation Facilitates aqueuos drainage

26. MICROSCOPIC STRUCTURE

27. SUPRACILIARY LAMINA outermost part Consist of pigmented collagen fibres Posteriorly continuation of suprachoroidal lamina Anteriorly continous with anterior limiting membrane

28. CILIARY MUSCLES 1.Longitudinal muscle(Outer) Attached anteriorly to scleral spur, outer trabecular meshwork 2.Radial muscle/oblique Attached to the inner uveal mesh work 3.Circular muscle(inner muscle) Primarily attached to the ciliary and iris stroma Posteriorly muscle are attached to elastic structure of par planna vessels and Bruch’ s elastic

29. Function : Role in accommodation Ciliary muscle contraction also causes opening of intertrabecular spaces/pore -facilitates aqueous filtration

30. Vascular stroma major arterial circle lies Formed by anastomosis of long and short PCA Supplies iris and ciliary body

31. EPITHELIUM Epithelium two layers Pigmented epithelium(PE) (outer – next to stroma) Anterior part continuous with anterior iris epithelium Posteriorly it is continuous with retinal pigment epithelium

32. Non-pigmented epithelium(NPE)( inner – faces post chamber) Columnar cells in pars plana, cuboidal cells in pars plicata Anterior part continuous with posterior iris epithelium Produces aqeuous humor and glycoprotein of vitreous cells are interlinked by tight junction called zonulae occludentes Diffusion barrier between blood and aquous ( blood aqueous barrier)

33. STRUCTURAL ANATOMY - EPITHELIUM

34. Internal limiting membrane lines NPE Forward continuation of internal limiting membrane of retina

35. CILIARY PROCESS 70-80 finger-like projections with vascular core radiating from pars plicata Occupy peripheral part of posterior chamber Each process is about 2mm long and 0.5mm in diameter Ciliary processes increases surface area for secretion

36. Grooves in between serve as attachment for lens zonules Zonules are the suspensory ligament of lens produced by ciliary epithelium Provide stability of lens and accommodation

37. MICROSCOPIC STRUCTURE Network of capillaries- in the centre Has endothelium with fenestrae Stroma of ciliary processes thin, separates capillaries from epithelium Epithelium two layered with apical apposition

38. CHOROID Highly pigmented, vascular loose connective tissue Rich in melanocytes gives characteristic dark color Situated between sclera and retina Extends from optic nerve to ciliary body (at ora serrata) Thickness decreases from post (0.22mm) to ant (0.1mm)

39. MICROSCOPIC STRUCTURE

40. Suprachoroidal lamina- lamina fusca Thin layer(10-32nm) with condensed collagen fibers , melanocytes and fibroblast continues anteriorly with supraciliary lamina of ciliary body Suprachoroidal space Interface/transition zone between choroid and sclera Composed of interconnected lamellar fibers that connected choroid and sclera contains long and short posterior ciliary arteries and nerves Potential space- may get filled up with blood/fluid in diseased eye

41. Stroma plenty of pigmented cells, macrophages,mast and plasma cells Vessels- form the bulk Arranged in two layers- outer consisting of large vessels ( hallers layer) inner of medium vessels ( sattlers layer)

42. Choriocapillaris Mono layers of broad wide capillaries between the plane of artery and Bruch’s membrane Choriocapillaries measure 20-50 um in diameter Capillaries are flattened providing large surface are for metabolic exchanges. Function It supplies oxygen and nutrients to Bruch’s membrane and outer third of retina except in macula . Choriocapillaries

43. Bruch’s membrane Also called lamina vitrea Extend from optic nerve head to ora serrata Thin refractile connective tissue (membrane) between choriocapillaris (choroid) and RPE (retina) Prevents choroid vessels from penetrating the retina but allows nutrients, proteins Constitutes element of both retina and choroid

44. Microscopically is composed of Basement membrane of RPE Inner collagenous layer Elastic tissue layer Outer collagenous layer Basement membrane of choriocapillaris

45. With increasing age although there is atrophy of choriocapillaris, there is increase in Bruch’s membrane Drusen- visible deposits between RPE basement membrane and inner layer of collagenous layer of Bruch’s membrane

46. BLOOD SUPPLY It has two arterial system Anterior arterial system Posterior arterial system

47. 1.Anterior arterial system

48. Posterior arterial Posterior ciliary artery branches several time in orbit giving rise into Short posterior ciliary artery(SPCA) 10-20 cluster of short posterior ciliary artery(SPCA) perforate sclera (2-2.5)mm from the optic disc. Nasal ciliary artery supplies nasal quadrant of choroid vise versa Long posterior ciliar artery(LPCA) pierce the sclera (3-4) mm from the optic disc outside the ring of PSCAs Supply choroid, give branches to choriocapillaries and terminate in main arterial circle of iris

49. VENOUS DRAINAGE Anterior ciliary veins- tributaries of muscular veins Smaller veins from sclera- carry blood only from sclera and not from choroid Vena vorticosae - 4 in no. Drain whole of choroid

50. Vortex veins 2 superior and 2 inferior vortex vein Vortex vein lie (2.5-3.5)mm posterior to the equator Vortex vein are closely related to IO and SO muscle Superior and two inferior vortex vein drains into superior and inferior ophthalmic vein respectively

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