2. Introduction
Peripheral organs of vision
Lens produces images-fall on retina-cells of
retina convert light image to nervous
impulses- that pass through optic nerve-
visual pathway- cerebral cortex- visual areas
6. Eyeball – tunics or layers
3 layers
Outer- fibrous coat consisting of sclera
&cornea
Middle – vascular coat consisting of
choroid,ciliary body,iris
Inner- nervous coat containing retina
7.
8. Outer Fibrous layer
It consists of the sclera and cornea,
which are continuous with each other.
Their main functions are to provide shape to
the eye and support the deeper structures.
9. sclera
posterior 5/6 forms thick white opaque
membrane of the outer fibrous coat
It is visible as the white part of the eye
Formed of dense fibrous tissue
10. sclera
.
Continuous with the cornea anteriorly
Sclero corneal junction s called as limbus
scleral spur-Behind the limbus a triangular mass projects into cornea
Sinus venosus sclerae – circular channel located in sclera just behind
the limbus
External surface s covered with ocular conjunctiva
14. cornea
Forms the anterior 1/6 th of outer fibrous layer
transparent and positioned centrally at the front of the eye.
Avascular and nourished by capillaries of limbus
Highly sensitive
Supplied by ophthalmic division of trigeminal nerve
It permits the entry of Light & refracts the entering light.
Junction of cornea to sclera s marked on exterior of eyeball- sulcus sclerae
15.
16. Vascular middle coat/ uveal tract
The vascular layer of the eye lies underneath the fibrous
layer.
It contains most of blood vessels of eye ball
It consists of from behind forwards
choroid,
ciliary body
Iris
17.
18. Choroid
Highly vascular with blood vessels
Larger posterior part of vascular coat
Lines inner surface of sclera
Anteriorly connected to iris by ciliary body
pierced by optic nerve posteriorly
Containing pigment cells – gives dark brown colour
It prevents reflection of light with in the eyeball
19. Layers
Outer to inner
Supra choroid lamina
Separates the sclera by supra choroid lamina
outer vascular layer with arteries and veins
Arteries –short ciliary arteries
Veins-Presence of veins - 4/5 venae verticosae
Inner capillary lamina-consist of fine net work of capillaries
basal laminae membrane of Bruch-Separates from retina
Diffusion occurs though this membrane
It provides nourishment to the outer layers of the retina.
20. Ciliary body
Anterior thickened continuation of choroid
Continuous with iris in front
They suspends the lens via suspensory ligaments
– comprised of3 parts –ciliary ring, the ciliary muscle and ciliary
processes.
Ciliary ring- outer fibrous ring, continuous with choroid
Ciliary processes -60-90 folds at inner aspect of ciliary body, formed of
complex capillaries, secretes aqueous humour
The ciliary muscle- consists of a collection of smooth muscles fibres.
Radially arranged fibres and inner circular fibres
Main function to focuss the lens for near vision
24. Inner nervous coat/retina
its light detecting component.
From retina nerve fibres arises from ganglion
layer to form optic nerve
That attach to posterior pole of eye bole
optic disc- Region through which area fibres
moves out
No photoreceptors present in optic disc –
known as blind spot
Optic disc pierced by central artery and vein
25.
26. The optic part of the retina can be viewed
during ophthalmoscopy.
The centre of the retina -macula.
yellowish in colour, and highly pigmented.
The macula contains a depression called- fovea
centralis,
which has a high concentration of light detecting
cells.
It is the area responsible for high acuity vision.
The area that the optic nerve enters the retina is
known as the optic disc
– it contains no light detecting cells.
27.
28. Pigmented (outer) layer –
formed by a single layer of cells.
It is attached to the choroid and supports the
choroid in absorbing light (preventing
scattering of light within the eyeball).
It continues around the whole inner surface of
the eye.
Neural /sensory(inner) layer –
consists of photoreceptors, the light detecting
cells of the retina.
It is located posteriorly and laterally in the
eye.
31. Structures of the Eyeball
Vitreous Body
a transparent gel which fills the posterior segment of
the eyeball (the area posterior to the lens).
is marked by a narrow canal which runs from the
optic disc to the lens – the hyaloid canal.
The vitreous body has three main functions:
Contributes to the magnifying power of the eye
Supports the lens
Holds the layers of the retina in place
32.
33. Lens
Biconvex.
Attached to ciliary body by suspensory
ligament
Behind the iris
Posterior surface lies in a depression if vitrous
body –hyaloid fossa
34.
35. Anterior and Posterior Chambers
two fluid filled areas in the eye – anterior and posterior
chambers.
The anterior chamber is located between the cornea and the iris,
and the posterior chamber between the iris and ciliary
processes.
chambers are filled with aqueous homour –
a clear plasma-like fluid that nourishes and protects the eye.
The aqueous humour is produced constantly, and drains via the
trabecular meshwork, an area of tissue at the base of the
cornea, near the anterior chamber.
If the drainage of aqueous humour is obstructed, a condition
known as glaucoma can result.