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
8. MACROSCOPIC
APPEARANCE
TWO SURFACES
1)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
9.
10.
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
13. 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
14. 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
Pigment cells- melanocytes
Lymphocytes, fibroblast and macrophages
15. 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
16.
17.
18.
19. FUNCTIONS OF IRIS
Controls amount of light entering the eye through
pupil
Defines eye colour
Control depth of field
Source of blood ocular tissues
20. 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
21.
22. MICROSCOPIC STRUCTURE
1)
• Supraciliary lamina-
2)
• Stroma
3)
• Layer of pigmented epithelium-
4)
• Layer of non pigmented epithelium-
5)
• Internal limiting membrane
23. MICROSCOPIC STRUCTURE
1.SUPRACILIARY LAMINA- outermost part
Consist of pigmented collagen fibres
Posteriorly continuation of suprachoroidal lamina,
ant continous with anterior limiting membrane
24. 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
25. 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
26. 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
27. FUNCTIONS OF CILIARY BODY
Site of aqueous humour production
Maintenance of IOP
Constitutes blood aqueous barrier
Accommodation
Eicosanoids are synthesised in ciliary
body
28.
29. 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
32. 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
33. 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
34.
35. 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
36. 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
37.
38.
39.
40.
41.
42. 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