It's nice to see the world my eye eye eye. some animal they can see in the night very well

1. 23-12-2019

2. Human Eyeball (bulbus oculi):
• Optic axis: is the line that joins both the anterior and posterior
pole.
• Visual axis: is the line joining a point in cornea, little medial to
anterior pole and fovea centralis, situated lateral to posterior
pole.
• Orbital cavity or eye socket: is the bony cavity that the eyeball
is situated.
• Ocular muscles: are muscles that attach the eyeball and the
orbital cavity.
• Eyelids: are skin over the eyeball to protect from foreign
substances and excess light.
• Conjunctiva: is a thin mucus membrane, which covers the
exposed part of eye.
• Lacrimal gland: are gland that produce tear for moisten and
protection of the anterior eye.

5. WALL OF THE EYEBALL:
1. Outer layer (Tunica Externa/ Tunica
Fibrosa), which includes cornea and sclera.
2. Middle layer (Tunica Media/ Tunica
Vasculosa), which includes choroid, ciliary
body and iris
3. Inner layer (Tunica Interna/ Tunica
Nervosa), the retina.

7. • Optic disk – blind spot (optic papilla): is a pale
disk, situated near the center of the posterior
wall of eyeball.
• Macula lutea – yellow spot: a small yellowish
area, situated a little lateral to the optic disk in
retina. Due to the presence of a yellow pigment.
• Degeneration of macula lutea leads to blindness.
• Fovea Centralis: is a minute depression in the
center of macula lutea. Fovea is the region of
most acute vision because it contains only cones.
• Foveal Vision and Extrafoveal vision

9. • Intraocular fluid (fluid in eyeball): is responsible for the
maintenance of shape of the eyeball.
• Intraocular fluid is of two types:
A. Vitreous humor - vitreous body: a viscous fluid present
behind lens, in the space between lens and retina.
B. Aqueous humor: is a thin fluid present in front of retina.
It fills the space between lens and cornea.
• This space is divided into: anterior and posterior
chambers by iris.
• Intraocular pressure: is the measure of fluid pressure in
eye, exerted by aqueous humor. Normal intraocular
pressure varies between 12 and 20 mm Hg.
• Lens: of the eyeball is crystalline in nature, biconvex,
transparent and elastic structure. It is avascular and
receives its nutrition mainly from the aqueous humor.

11. Formation of Aqueous Humor by =
Ciliary process (body).
Formation of Vitrous Humor by =
Retinal vessels.

13. Ocular muscles:
• Muscles of the eyeball are of two types:
a) Intrinsic muscles: (Smooth Muscle Fiber, Autonomic Nerves)
1. Constrictor papillae
2. Dilator papillae
3. Ciliary muscle.
b) Extrinsic muscles: (Skeletal Muscle Fiber, Somatic Nerves)
1. Superior rectus
2. Inferior rectus
3. Medial or internal rectus
4. Lateral or external rectus
5. Superior oblique
6. Inferior oblique.

14. INNERVATION OF OCULAR MUSCLES:
A) Innervation of Intrinsic Muscles:
1- Parasympathetic nerve fibers
• Contraction of ciliary muscle.
• Constrictor pupillae.
2- Sympathetic nerve fibers
• Relaxation of ciliary muscle
• Contraction of dilator pupillae.
B) Innervation of Extrinsic Muscles:
1- Oculomotor (Third) nerve supplies:
• Superior rectus
• Inferior rectus.
• Medial rectus (internal rectus)
• Inferior oblique.
2- Trochlear nerve (Fourth) supplies the superior oblique
3- Abducent nerve (Sixth) supplies the lateral rectus (external rectus).

15. Innervation of Extrinsic Muscles
Innervation of Intrinsic Muscles

16. Visual process:
• Visual process is the series of actions that take place
during visual perception.
• These events take place during process of vision:
1. Image formation (inverted object).
2. Neuronal process (photoreceptors).
3. Chemical process (Development of action potential).
4. Transmission of Action potential through optic nerve
then to the visual area in the occipital lobe.

18. Retina contains the visual receptors
• Visual receptors are rods and cones.
• Each rod and cone composed of four structures:
1. Outer segment
2. Inner segment
3. Cell body
4. Synaptic terminal.
• Rhodopsin or visual purple is the photosensitive pigment of rod
cells.
• Porphyropsin or iodopsin or cyanopsin is the photosensitive
pigment of Cone cells.
• Visual or phototransduction is the process by which light energy
is converted into receptor potential in visual receptors.
• visual acuity: the ability of eye to determine the precise shape
and details of the object.

21. Melanin “Fuscin”.
Absorbs light.
Store vitamin A.
phagocytic action
Visual receptor
cells.
Light sensitive.
Chief supporting
elements “Müller
fibers”.
Granules & nuclei
Reticular
meshwork
small oval-shaped
flattened bipolar cells

23. ON and OFF bipolar cell responses to lightON and OFF bipolar cell activity in the dark

25. • Visual field: is the ability of one eye to see a part of the
external world when it is fixed in one direction.
• Visual filed is divided into four parts:
1. Temporal field 2. Nasal field
3. Upper field 4. Lower field.
• Corresponding retinal points: the two images developed on
retina of both eyes are fused into a single sensation.
• Visual pathway or optic pathway: is the nervous pathway
that transmits impulses from retina visual center in
cerebral cortex.
• First order neurons (primary neurons): from bipolar cell to
ganglionic cell.
• Second order neurons (secondary neurons): from
ganglionic cell to lateral geniculate body.
• Third order neurons: from lateral geniculate body to the
visual cortex

26. Visual pathway or optic pathway

28. • Pupillary reflexes: are the visceral reflexes, which alter the
size of pupil.
1. Light reflex:
• Light reflex is the reflex in which pupil constricts when
light is flashed into the eyes.
A. Direct light reflex
B. Indirect light reflex.
2. Ciliospinal reflex:
• Ciliospinal reflex is the dilatation of pupil in eyes caused by
painful stimulation of skin over the neck.
3. Accommodation reflex:
• Accommodation is the adjustment of eye to see either
near or distant objects clearly.

29. Lens accommodation

30. The corneal blink reflex

31. Color blindness
Ishihara charts