The uvea consists of the iris, ciliary body, and choroid. The iris develops from the neuroectoderm and vascular mesoderm and controls the amount of light entering the eye. The ciliary body develops from the neuroectoderm and mesoderm and is involved in aqueous humor production, accommodation, and maintaining intraocular pressure. The choroid develops from mesoderm and supplies the outer retina with blood and absorbs excess light. All three parts are supplied by short and long posterior ciliary arteries and drained by the vena vorticosa veins.

1. ANATOMY OF UVEA

2. INTRODUCTION
• UVEA constitutes- middle vascular coat
• 3 parts- a)iris
b)ciliary
body
c)choroid
• Developmentally,structurally and
functionally- indivisible
• color varies from light blue to dark brown

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

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

5. MILESTONES
• 9TH WEEK GESTATION- ciliary body
appears
• 12TH WEEK GESTATION- sphincter
pupillae appears
• 5TH MONTH- all layers of choroid seen
- iris fully developed
• 6TH MONTH- dilator muscle begins to
form, sphincter muscle is fully formed
• POSTNATAL PERIOD- dilator
muscle fully formed by 5 years, iris
stromal pigment develops after birth

6. 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

8. MACROSCOPIC APPEARANCE
TWO SURFACES
A)ANTERIOR SURFACE
• Collarette- zigzag line, 2mm from pupil, thickest,
represents attachment of pupillary membrane
• Divides surface into-
a) CILIARY ZONE- c/b
 Radial streaks
 Crypts- peripheral-near the iris
central- near collarette
 Contraction furrows- faints lines outside collarette
b) PUPILLARY ZONE-
 Between collarette and pigmented frill
 Pigmented frill- black pigment at pupillary margin
-represents ant end of optic cup

11. B)POSTERIOR SURFACE- dark
brown/black
Contains-
A)Schwalbe’s contraction folds- 1 mm
from pupillary border, little radial
furrows
B)Schwalbe’s structural furrows- 1.5 mm
from pupillary border
C)Circular furrows- finer then radial
furrows

12. 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 collagenous tissue with mucopolysaccharide
• Structures embedded-
 Sphincter pupillae- 1 mm broad circular band in pupillary
area
derived by ectoderm
supplied by parasympathetic fibres by 3rd
nerve constricts pupil

13.  Dilator pupillae- lies in posterior part of ciliary zone
supplied by cervical
sympathetics dilates pupil
 vessels- form bulk of stroma
radial vessels- branches of circulous arteriosis major
peculiarities- absence of IEL & non fenestrated capillary
endothelium
 Pigment cells- melanocytes
 Lymphocytes, fibroblast and macrophages
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

17. FUNCTIONS OF IRIS
• CONTROLS AMOUNT OF LIGHT
ENTERING THE EYE THROUGH PUPIL
• DEFINES EYE COLOUR
• CONTROL DEPTH OF FIELD
• SOURCE OF BLOOD OCULAR TISSUES

18. 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
a)Anterior part- ciliary processes (pars plicata) 2-
2.5mm
b)Posterior part- smooth (pars plana) 5mm wide
temporally & 3mm nasally
MICROSCOPIC STRUCTURE
1.SUPRACILIARY LAMINA- outermost part
 Consist of pigmented collagen fibres
 Posteriorly continuation of suprachoroidal lamina,
ant continous with anterior limiting membrane

20. 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- in inner portion, nearest to lens
 Radial fibres- obliquely placed
Actions - slacken suspensory ligament thus
helps in accomodation
circular fibres- directly as sphincter
nerve supply- parasym. fibres from ciliary
ganglion

21. Vascular stroma- major arterial circle lies
Formed by anastomosis of long and short
PCA
Supplies iris and ciliary body
3)Layer of pigmented epithelium-
forward continuation of RPE
Anteriorly continues to pigmented epithelium
of iris
4)Layer of non pigmented epithelium-
forward continuation of sensory retina
Continues anteriorly with pigmented
epithelium of iris
5)Internal limiting membrane-lines NPE
Frwd continuation of internal limiting
membrane of retina

22. 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

24. FUNCTIONS OF CILIARY
BODY
• Site of aqueous humour production
• Maintenance of IOP
• Constitutes blood aqueous barrier
• Accommodation
• Eicosanoids are synthesised in ciliary
body

25. 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

27. 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)
3) choriocapillaris- rich capillary network
• Supplies pigment epithelium and outer layers of sensory
retina

28. 4)Basal lamina- bruch’s
membrane/lamina vitrae
• Innermost layer
• Between choriocapillaris and RPE
• Electron microscopy- basement
membrane of RPE, inner collagen,
middle elastic and outer collagen and
basement membrane choriocapillaris
• With increasing age- produces
hyaline excresences known as
druscens

30. 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

31. BLOOD SUPPLY UVEAL TRACT
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
3)ANTERIOR CILIARY ARTERIES
• From muscular arteries
• 7 in number
• 2 each SR,IR,MR and 1 from LR
• Anastomse with LPCA
• Circulous arterious major and minor

35. VENOUS DRAINAGE
1)Anterior ciliary veins- tributaries of
muscular veins
2)Smaller veins from sclera- carry
blood only from sclera and not from
choroid
3)Vena verticosae- 4 in
no. Drain whole of
choroid