5. Protect the eye from injury
Reflex closure of eyelids occurs
when some object comes close to
the eye or bright light shines into
eye (corneal reflex)
Regular blinking assists in
distribution of tears and prevents
drying of the tear film
6. A transparent mucous membrane that lines the inner surfaces of
the eyelids and the front surface of the eyeball.
7. The Palpebral conjunctiva
Starts at the lid margins and
is firmly attached to the
posterior tarsal plate
The Fornical conjunctiva
Is loose and redundant and
maybe thrown into folds
The Bulbar conjunctiva
Covers the anterior sclera and
is continuous with the corneal
epithelium at the limbus
8. Epithelium
is non-keratinizing and about five cell
layers thick
Basal cuboidal cells evolve from the
surface
Goblet cells are located within the
epithelium
Stroma
Consists of richly vascularized loose
connective tissue
Accessory lacrimal glands of Krause
and Wolfring are located deep within
the stroma
9. The transparent dome
which serves as the
window of the eye.
The primary (most
powerful) structure
focusing light entering
the eye.
10. Cornea is composed of 5
layers
Epithelium.
Bowman’s membrane.
Stroma
Descemet’s membrane.
Endothelium).
11. No blood vessels.
Transparent stroma with low level of fluids.
Endothelium cells serves as a pump that supply oxygen and
remove fluids.
Tear film also supplies oxygen and keep corneal
surface smooth and clean.
12. The white, opaque cover of the
eye.
Covers 80% of the eye’s outer
layer.
Contains thick elastic collagen.
It provides protection.
Serves as an attachment for the
extra-ocular muscles which
move the eye.
14. The iris is composed of
Endothelium
Stroma
Epithelium
Stroma muscles
Dilator - sympathetic innervation
Constrictor – parasympathetic
innervation
15. Determined by the amount of pigment
present in iris.
No pigment - pink iris (albino), some
pigment – blue iris, increasing amounts of
pigment- green>hazel> brown irides.
The pigments: melanin (chromosome 15)
and lipochrome (chromosome 19).
Heterochromia irides: when one iris has a
different color than the other iris.
16. The pupil is the clear area that is located in
the center of the iris of the eye.
It appears black because most of the light
entering the pupil is absorbed by the
tissues inside the eye
In darkness the iris dilator muscle causes
the pupil to “dilate” and allowing more
light to reach the retina.
In brightness, the iris sphincter muscle
(which encircles the pupil) constricts,
causing the pupil to “constrict” and
allowing less light to reach the retina.
Constriction also occurs during accommodation
- the “near reflex.”
17. Pars plana – flat area
continuous with the retina
Pars plicata – contains the
ciliary processes that secretes
the aqueous humor
Ciliary muscle runs circularly
around the eye and controlles
accommodation
18. The posterior segment of the uvea, between the sclera and the
retina.
Reach in blood supply, supplies oxygen and nutrition to the
outer two thirds of the retina.
19. Produced by the ciliary
body.
Entering from the posterior
chamber, it passes through
the pupil into the anterior
chamber and filtrates
through the angle into the
blood stream.
Serves to nourish ocular
structures.
20. Iris-corneal junction
Contains the trabecular meshwork
(TM )which acts like a filter for the
aqueous humor.
From the TM the humor drains to
schlem’s canal and then to blood stream.
21. Biconvex, avascular,
transparent structure.
Suspends behind the iris by
the zonules which are
connected to the ciliary body.
Serves to converge light onto
the retina.
22. Ciliary muscle constrict >
zonular tension decreases > lens
becomes more spherical >
more dioptric power that
converge light from a near
target onto the retina.
23. This loss of transparency, or opacity formation is called
Cataract
24. The innermost layer of the eye.
The retina is a multi-layered
sensory tissue that lines the
back of the eye.
It contains millions of
photoreceptors that capture
light rays and convert them
into electrical impulses.
These impulses travel along
the optic nerve to the brain
where they are turned into
images.
25. Fovea: area with the highest concentration of photoreceptors.
Central retina: A circular field of approximately 6 mm around the
fovea.
Peripheral retina: stretching to the ora serrata.
26. Phptoreceptors
Cones
Concentrated in the fovea
Most active in daylight
Central vision
Rods
Mostly in the peripheral
retina
Most active in night vision
Peripheral vision
27. Consists of 1.2 million axons that arise from the retina.
Leaves the eye through the optic disc also known as the blind
spot.
