structure of eye introduction sclera cornea choroid ciliary body iris retina compartment of eye lens clinical anatomy

2. •Eye is the organ of sight.it functions like a
camera and has lens system for focusing images.
•Location : in the orbital cavity.
•Shape & size: almost spherical, 24mm diameter.
•Fascial sheath: it is covered by a membranous
Tenon’s capsule

3. •Tunics or coats of eye: it has 3 coats-
•1. outer fibrous coat consisting of sclera
and cornea.
•2. middle vascular coat consisting of
choroid and ciliary body
•3. inner nervous coat consisting of retina
and iris.

5. Sclera
•It is opaque and a small part of it is visible as white
of the eye.
•It forms posterior 5/6th of the outer coat.
•It is continuous anteriorly with cornea.
•Functions :
1. It maintains shape of eye.
2. Protects internal structures.
3. Provides attachment to extraocular muscles.

6. Cornea
•It forms anterior 1/6th of the outer coat.
•It is transparent, avascular and highly sensitive to
touch.
•Functions:
•1. It permits the light to enter the eye.
•2. It refracts the entering light

7. Middle coat – Choroid
•It is larger posterior part of the vascular coat.
•It is brown, thin and highly vascular.
•It is connected to iris by ciliary body.
•Function: it nourishes the rods and cones of
retina.

8. Ciliary body
•It is a circular thickening made up of smooth muscle
and iris is attached to it.
•Ciliary body suspends the lens via suspensory
ligaments or zonules.
•Function:
1. it helps in suspension of lens.
2. it is responsible for accomodation of eye. This
allows a person to adjust for near vision.
3. it secretes aqueous humor of the eye.

9. Inner coat -Iris
•It is a pigmented contractile diaphragm
present between the cornea and lens. In the
centre it presents an opening called pupil
which regulates the entry of light into the
eye.
•layer of smooth muscle arranged in
constrictor pupillae, dilator pupillae.

10. Retina
•It is the innermost coat of eyeball.
•Retina is divided into 10 layers. These are:
•1. pigment layer: 2. layer of rods & cones: these are
photoreceptors.
•3. outer limiting membrane
•4. outer nuclear layer
•5. outer plexiform layer
•6. inner nuclear layer
•7. inner plexiform layer
•8. ganglion cell layer
•9. nerve fibre layer
•10. internal limiting membrane.

11. Compartments of eye
•It is divided into two chambers by iris: anterior
and posterior.
•These chambers are filled with aqueous humor
which helps in maintaining the intraocular
pressure.
•Posterior compartment is also filled with vitreous
humor.

12. Lens
•It is transparent & biconvex shaped body.
•It is present between anterior and posterior chambers.
•It has anterior and posterior surfaces.

13. Clinical anatomy
•Transparency of cornea is essential for
adequate vision. It can be affected in :
injuries, semisoft contact lenses, vitamin A
deficiency.
• Fatty degeneration of periphery of cornea is
visible as white ring due to aging. It is known
as arcus senilus.
• Papilloedema: in this condition, normal cup
shaped area of optic disc is obscured &
margins of cup become blurred due to
increased intracranial pressure.

14. •Night blindness : deficiency of vitamin A initially affects
rods leading to night blindness or nyctalopia. Later on
cones are also affected.
•Myopia : light rays are focused in front of retina and
image is blurred. It is cured by using concave lenses.
•Hypermetropia : when light rays are focused behind the
retina & image is blurred. It is cured by convex lenses.
•Presbyopia : inability to clearly see the near objects.
Primary complaint is difficulty in reading. It can be
cured by convex lenses.

15. •Glaucoma : increased intraocular pressure.
•Opacification of lens is known as cataract . Its
most common cause is age factor. Lens become
yellow & hard and ultimately opaque so that light
can not pass through it. It is easily cured by
surgery.
•Astigmatism : it is defective focusing of image
on retina due to alterations in horizontal & vertical
curvatures of cornea. It is cured by cylindrical
lenses.