anatomyofuvea , iris , ciliary body , choroid

The iris consists of two layers: the front pigmented fibrovascular layer known as a stroma and, beneath the stroma, pigmented epithelial cells.

The stroma is connected to a sphincter muscle (sphincter pupillae), which contracts the pupil in a circular motion, and a set of dilator muscles (dilator pupillae), which pull the iris radially to enlarge the pupil, pulling it in folds.


The iris (brown coloured portion of the eye) controls the size of the pupil by contracting the sphincter pupillae and dilator pupillae muscles
The sphincter pupillae is the opposing muscle of the dilator pupillae. The pupil's diameter, and thus the inner border of the iris, changes size when constricting or dilating. The outer border of the iris does not change size. The constricting muscle is located on the inner border.

The back surface is covered by a heavily pigmented epithelial layer that is two cells thick (the iris pigment epithelium), but the front surface has no epithelium. This anterior surface projects as the dilator muscles. The high pigment content blocks light from passing through the iris to the retina, restricting it to the pupil.[3] The outer edge of the iris, known as the root, is attached to the sclera and the anterior ciliary body. The iris and ciliary body together are known as the anterior uvea. Just in front of the root of the iris is the region referred to as the trabecular meshwork, through which the aqueous humour constantly drains out of the eye, with the result that diseases of the iris often have important effects on intraocular pressure and indirectly on vision. The iris along with the anterior ciliary body provide a secondary pathway for aqueous humour to drain from the eye.


The iris is divided into two major regions:

The pupillary zone is the inner region whose edge forms the boundary of the pupil.
The ciliary zone is the rest of the iris that extends to its origin at the ciliary body.

1. Anatomy of Uvea PRESENTED BY : Dr MOHIT KUMAR JHA OPHTHALMOLOGY RESIDENT CIVIL HOSPITAL , PANCHKULA

2. Introduction UVEA – Middle Vascular Part of Eyeball 3 parts : IRIS CILIARY BODY CHOROID Entire Uveal tract is developmentally , structurally and functionally one indivisible structure

3. Embryology 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 CILIARY BODY Both Epithelium from neuroectoderm Ciliary processes from ciliary epithelium Stroma and blood vessels – mesoderm

4. TIMELINE

5. IRIS Anterior most part Avg diameter- 12mm, thickness- 0.5mm In centre an aperture of 3-4mm- PUPIL Thinnest at its root- tears away easily on blunt trauma- IRIDODIALYSIS Divides space into anterior and posterior chamber

6. Macroscopic structure ANTERIOR SURFACE Collarette - zigzag line, 2mm from pupil margin, thickest region of iris, represents attachment of pupillary membrane. Divides surface into- A) CILIARY ZONE- c/b Radial streaks- Due to underlying radial vessels Crypts- Depressions where superficial layers of iris is missing peripheral-near the iris root central- near collarette Contraction furrows- faint lines outside collarette , becomes prominent when the pupil dilates

7. B) PUPILLARY ZONE- Between collarette and pigmented pupillary frill. Relatively smooth and flat Pigmented frill- fringe of black pigment at pupillary margin represents ant end of optic cup

8. POSTERIOR SURFACE- dark brown/black in colour . Contains- Schwalbe’s contraction folds - 1 mm from pupillary border, little radial furrows Schwalbe’s structural furrows- 1.5 mm from pupillary border. Narrow and deep to start with and become wide and shallow as they approach ciliary margin Circular furrows- finer then radial furrows. Crosses structural furrows at regular intervals. More marked near the pupil and formed due to difference in thickness of pigmented epithelium.

9. Microscopic structure FOUR LAYERS- a)Anterior limiting layer- consists melanocytes and fibroblasts , Previously called endothelial layer. Colour of iris depends on this layer Blue iris- thin layer and few pigment cells Brown iris- thick and doubly pigmented b) Iris stroma- Forms main bulk Consists of loosely arranged collagenous network with mucopolysaccharide ground substance Structures embedded-muscles , vessels , nerves , pigment cells and other cells which include fibroblast , lymphocytes and macrophages

10. Sphincter pupillae- 1 mm broad circular band in pupillary area flat bars of plain muscle fibres derived by ectoderm supplied by parasympathetic fibres by 3 rd nerve constricts pupil Dilator pupillae- lies in posterior part of ciliary zone supplied by cervical sympathetics dilates pupil

11. c) Anterior epithelial layer anterior continuation of pigment epithelium of retina and ciliary body Lacks melanocytes Basal processes- give rise to dilator pupillae D)Posterior pigmented epithelial layer Anterior continuation of non pigmented epithelium of ciliary body Derived from internal layer of optic cup Forms pigmented frill

12. Ciliary Body Forward continuation of choroid at ora serrata Triangular in cut section, ant side of its form part of angle , in middle attached to iris and outer part lies against sclera Triangle – two parts Anterior part- ciliary processes ( pars plicata ) 2-2.5mm Posterior part- smooth ( pars plana ) 5mm wide temporally & 3mm nasally

13. Microscopic Structure 1.SUPRACILIARY LAMINA- outermost part Consist of pigmented collagen fibres Posteriorly continuation of suprachoroidal lamina, ant continous with anterior limiting membrane

14. 2.STROMA- Consists Ciliary muscle - non striated, triangular in cut section, 3 parts Longitudnal /meridional fibres - origin from scleral spur, inserts into suprachoroidal lamina Circular fibres - occupies ant and inner portion, nearest to lens Radial fibres - obliquely placed Actions - slacken suspensory ligament thus helps in accomodation circular fibres - directly act as sphincter nerve supply- parasym . fibres from ciliary ganglion

15. 3)Layer of pigmented epithelium- forward continuation of RPE Anteriorly continues to anterior epithelium of iris 4)Layer of non pigmented epithelium- forward continuation of sensory retina Continues anteriorly with posterior pigmented epithelium of iris 5)Internal limiting membrane-lines NPE Forward continuation of internal limiting membrane of retina

16. Ciliary Processes Finger like projections from pars plicata 70-80 in number, 2mm long 0.5mm diameter Site of aqueous production ULTRASTRUCTURE 1)Network of capillaries- in the centre Has endothelium with fenestrae 2)Stroma of ciliary processes- thin, separates capillaries from epithelium 3)Epithelium-two layered with apical apposition

17. Choroid Posterior most part Extension- optic disc to ora serrata Inner surface- smooth, brown and in contact with RPE Outer surface-rough and in contact with sclera Thickness- posteriorly 0.22mm anteriorly 0.10mm

18. Microscopic structure 1) Suprachoroidal lamina- 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 )

19. 3) choriocapillaris - rich capillary network Supplies pigment epithelium and outer layers of sensory retina 4) Basal lamina- bruch’s membrane Innermost layer Between choriocapillaris and RPE Electron microscopy- basement membrane of RPE, inner collagen, middle elastic and outer collagen and basement membrane choriocapillaris

20. BLOOD SUPPLY UVEAL TRACT

21. VENOUS DRAINAGE Vena verticosae - 4 in no. Drain whole of choroid Receive small veins from optic nerve head Superior veins open into sup.ophthalmic vein and inf. Into inf.ophthalmic vein.

22. Functions of uvea Source of Blood Flow to ocular tissues Site of Aqueous Humour productionand maintenance of IOP Constitues the blood-aqueous barrier Accomodation Eicosanoids are synthesized in iris and CB Uveal tissue plays role in detoxification and antioxidation in the anterior segment.

23. UVEITIS ( APPLIED ASPECTS) Inflammation of uveal tract Usually U/L CLASSIFICATION- ANTERIOR- iritis, iridocyclitis INTERMEDIATE- cyclitis, pars planitis POSTERIOR- retinitis, chorioretinits PANUVEITIS

24. CONGENITAL ANOMALIES HETEROCHROMIA IRIDUM POLYCORIA - more then one pupil CORECTOPIA - abnormally eccentric pupil

25. 4. ANIRIDIA- abscence of iris o/e- a narrow rim of iris tissue behind sclera seen oftenly zonules of lens and ciliary processes often visible 5. PERSISTENT PUPILLARY MEMBRANE- Persistent part of ant vascular sheath of lens Attached to collarate

26. COLOBOMA UVEA- defect in tissue incomplete closure of the embryonic fissure during development Associations- micropthalmia , cataract, glaucoma, refractive error, CHARGE syndrome, colobomas of lids/lens/retina Mutation PAX2 gene Types – a) typical – inferonasal quadrant, pupil is pear shaped Choroidal coloboma- oval, rounded apex towards disc, vessels traversing disc, disc may be involved b)atypical- elsewhere, iris involved etiology- intrauterine inflammations

27. CYST OF IRIS- congenital cyst may arise from a)stroma b)pigment epithelium

28. BRUSHFIELD SPOTS IN DOWNS SYNDROME LISCH NODULES IN NF1

29. Thank you