anatomy of uvea

1. ANATOMY OF UVEA
MODERATOR- DR. H.N. HAZARIKA
PRESENTER- DR BARUN GARG

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 apposition

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
• Few anastomosis with CRA

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

36. 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

38. UVEITIS
• Inflammation of uveal tract
• Usually U/L
• CLASSIFICATION-
A)ANATOMICAL
1. ANTERIOR- iritis, iridocyclitis
2. INTERMEDIATE- cyclitis, pars planitis
3. POSTERIOR- retinitis, chorioretinits
4. PANUVEITIS
B)PATHOLOGICAL
1. GRANULOMATOUS
2. NON GARNULOMATOUS

40. CONGENITAL ANOMALIES
1.HETEROCHROMIA-
• Iridum
• Iridis
2.POLYCORIA- more then one pupil
3.CORECTOPIA- abnormally eccentric pupil

41. 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

42. 5.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 and fibrovascular
sheath persistence

44. CYST OF IRIS- congenital cyst may arise from
a)stroma- derived from ectopic cells of
surface ectoderm of developing lens
b)pigment epithelium- due to failure of fusion
of two layers of optic vesicle

45. Axenfeld anomaly Rieger anomaly
Peter's anomaly Sclerocornea
Abnormal neural crest cell migration

46. Abnormal neural crest cell
proliferation
Iridocorneal Endothelial Syndrome
Progressive iris atrophy
Iris naevus (Cogan-Reese) syndrome
Chandler syndrome

47. BRUSHFIELD SPOTS IN DOWNS SYNDROME
LISCH NODULES IN NF1