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Anatomy, bood supply of UVEA- iris, ciliary body and choroid .pptx
- 1. ANATOMY OF UVEA DR.DETTY JOSE
- 2. UVEA It constitutes themiddle vascular coat of eyeball Divided into three parts: 1)iris 2)ciliary body 3)choroid
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- 4. • Thin circulardisc with a central 4mm aperture – PUPIL , which regulates the amount of light reaching retina. •Average diameter is 12mm and thickness is about 0.5mm. • Iris is attached to the middle of anterior surface of ciliary body. • It divides the space between cornea and lens into ant. and posterior chamber
- 5. MACROSCOPIC APPEARENCE ANTERIOR SURFACE Itis divided into : ciliary and pupillary zone by a zigzag line called COLLARETTE • CILIARY ZONE: It is characterized by: a. Radial streaks- due to underlying blood vessels. b. Crypts – These are depressions where superficial layer is absent; arranged in two rows- peripheral and central • PUPILLARY ZONE: between collarette and pigmented pupillary frill.
- 7. B)POSTERIOR SURFACE- darkbrown/black • SCHWALBE’S CONTRACTION FOLDS-1 mm from pupillary border, little radial furrows • SCHWALBE’S STRUCURAL FURROWS-1.5 mm frompupillary border • CIRCULAR FURROWS- finer and cross the structural furrows at regular intervals.
- 8. MICROSCOPIC APPEARENCE Iris consistsof 4 layers. •Anterior limiting membrane - anterior condensed part of stroma. Contains melanocytes and fibroblasts. Its deficient in areas of crypts. Colour of irs depends on this. •Stroma- It forms the bulk of iris tissue. Contains sphincter pupillae, dilator pupilae, nerves, vessels and cells
- 9. I. SPHINCTER PUPILLAEMUSCLE- It consists of plain muscle fibres that forms a circular band in the pupillary zone. supplied by parasympathetic fibres through third nerve- it constricts the pupil. II. DILATOR PUPILLAE MUSCLE – Lies in posterior part of stroma of ciliary zone. Supplied by cervical sympathetics – it dilates the pupil. III. VESSELS- It forms the bulk of iris, arranged radially and responsible for the radial streaks. These are straight when pupil constricts and wavy when kit dilates
- 11. • Anterior epitheliallayer: anterior continuation of pigment epithelium of retina and ciliary body. It lacks melanocytes. It continues anteriorly upto the pupillary margin as cuboidal epithelial cells. It gives rise to dilator pupilae muscle. Posterior pigmented epithelial layer: continuation of non-pigmented epithelium of ciliary body, it forms pigmented frill. It has a thin basement layer which lines the posterior chamber.
- 13. IRIS AND PUPILPHYSIOLOGY In bright light there is activation of parasympathetic nervous system In dim light sympathetic system is activated
- 14. EMBRYOLOGY OF IRIS •Both layers of epithelium derived from marginal region of optic cup (neuroectoderm) • Sphincter and dilator pupillae- anterior epithelium (neuroectoderm) • Stroma and vessels- vascular mesoderm
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- 16. CILIARY BODY • Forwardcontinuation of choroid at ora serrata • Triangular in cut section, anteror side of its form part of angle , in middle , it gives attachment to iris and outer part lies against sclera with suprachoroidal space in between. • Inner side of Triangle – two parts a) Anterior part- ciliary processes (pars plicata or corona ciliaris) 2- 2.5mm wide b)Posterior part- smooth (pars plana or orbicularis ciliaris) 5mm wide temporally & 3mm nasally
- 18. MICROSCOPIC STRUCTURE 1.SUPRACILIARY LAMINA- Outermost condensed part of stroma Consist of pigmented collagen fibres Posteriorly continuation of suprachoroidal lamina, ant continous with anterior limiting membrane of iris. 2. STROMA It consists of connective tissue of collagen and fibroblasts- ciliary muscles, vessels, nerves and cells are embedded in it.
- 19. CILIARY MUSCLE – Nonstriated, triangular in cut section, 3parts • Longitudnal/meridional fibres- origin by tendinous fibres from scleral spur and trabeculae, inserts into suprachoroidal lamina • Circular fibres- occupies anterior and inner portion, run parallel to the limbus, lie nearest to lens. • Radial fibres- obliquely placed and becomes continuous with circular fibres Actions - slacken the suspensory ligament thus helps in accomodation circular fibres- act as sphincter Nerve supply- parasym. fibres from ciliary ganglion
- 22. VASCULAR STROMA OFCILIARY BODY The major arterial circle lies in the stroma Formed by the anastomosis of long posterior and anterior ciliary arteries. 3. LAYER OF PIGMENTED EPITHELIUM Forward continuation of retinal pigment epithelium and continues as anterior pigment epithelium of iris. 4.LAYER OF NON PIGMENTED EPITHELIUM Forward continuation of sensory retina and anteriorly continues as posterior pigmented epithelium of iris.
- 23. 5. INTERNAL LIMITINGMEMBRANE It lines the non pigmented epithelium and forward continuation of internal limiting membrane of retina
- 25. CILIARY PROCESSES • Fingerlike projections from pars plicata • 70-80 in number, each about 2mm long 0.5mm diameter • Site of aqueous production. • Ciliary processes increases the surface area for production • The grooves in between gives attachment to suspensory ligaments • Provides stability to lens and helps in accomodation
- 26. ULTRASTRUCTURE 1)Network of capillaries-it occupies the centre Has fenestrated endothelium 2)Stroma of ciliary processes - thin, separates capillaries from epithelium. 3)Epithelium -two layered ; outer pigmented and inner non pigmented epithelium. Tight junction between the cells form blood- aqueous barrier.
- 27. Structural anatomy- epithelium •Two layer of epithelial cells of ciliary body forms a unique combination • Basolateral surface of NPE cells faces aqueuos humor and basolateral surface of PE cell faces towards the stroma • Apical surfaces of PE and NPE cells are justaposed with gap junction • Two Epithelial cell is considered functional unit. • This unique combination of two epithelial cells is important for secretion aqueous humour
- 29. EMBRYOLOGY OF CILIARYBODY • Both Epithelium from neuroectoderm • Ciliary processes from ciliary epithelium • Stroma and blood vessels – mesoderm
- 30. FUNCTIONS OF CILIARYBODY • Site of aqueous humour production • Maintenance of IOP • Constitutes blood aqueous barrier • Accommodation • Eicosanoids are synthesised in ciliary body
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- 32. CHOROID • Posterior mostpart • Extension- optic disc to ora serrata • Inner surface- smooth, brown and in contactwith RPE • Outer surface-rough and in contact with sclera • Thickness- posteriorly 0.22mm anteriorly 0.10mm
- 33. MICROSCOPIC STRUCTURE 1) Suprachoroidallamina or lamina fusca • Thin layer, continues anteriorly with supraciliary lamina of ciliary body • Suprachoroidal space- contains long and short posterior ciliary arteries and nerves. 2) 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).
- 34. 4)Basal lamina- bruch’smembrane/lamina vitrae • Innermost layer • Between choriocapillaris and RPE • Electron microscopy- basement membrane of RPE, inner collagen, middle elastic and outercollagen and basement membrane choriocapillaris • With increasing age- produces hyaline excresences known as druscens. 3) choriocapillaris- rich capillary network • Supplies pigment epithelium and outer layers of sensory retina • fenestrated capillaries and endothelial cella are joined by zona occludens.
- 37. FUNCTIONS OF CHOROID •BLOOD SUPPLY TO OUTER FOUR LAYERS OF RETINA • MODULATION OF VASCULARISATION • REGULATE RETINAL HEAT • ASSIST IN THE CONTROL OF INTRAOCULAR PRESSURE • PIGMENT ABSORBS EXCESS LIGHT SO AVOIDING REFLECTION
- 38. BLOOD SUPPLY UVEALTRACT 1.SHORT POSTERIOR CILIARY ARTERIES • Branches of ophthalmic artery • Divides into 10-20 branches, pierce sclera around optic nerve • Supply choroid in segmental manner 2) LONG POSTERIOR CILIARY ARTERIES • Two in number- nasal and temporal • Pierce sclera • Anastomose with anterior ciliary arteries- form major arterial circle supply ciliary body
- 39. 3)ANTERIOR CILIARY ARTERIES •From muscular arteries • 7 in number • 2 each SR,IR,MR and 1 from LR • Anastomse with LPCA to form circulus arterious major near root of iris and branches from it forms the circulus arterious minor near the pupillary margin
- 42. VENOUS DRAINAGE 1)Anterior ciliaryveins- tributaries of muscular veins 2)Smaller veins from sclera- carry blood only from sclera and not from choroid 3)Vena verticosae (vortex veins or posterior ciliary veins)- 4 in no and pierces the sclera obliquely about 6 mm behind the equator. Drain whole of choroid
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