3. Eye lid
In addition to tear spreading, the eyelid is primarily
responsible for corneal nutrition
Also provides protection to cornea
Lashes offer additional protection
4. Lacrimal System/Tear Film
Lacrimal system is responsible for tear production
and drainage
Made up of 3 layers
Created primarily by lacrimal apparatus and
meibomian glands
Lubricate the eyeball, provides oxygen/nutrition
for cornea, has antibacterial properties and helps
wash away debris
Also have unique composition which keeps
surface of cornea slick.
6. Cornea
Made up of 5 layers
Specialized Transparent Tissue
No blood vessels
Primarily responsible for refracting light
Does more of the job than the lens
More nerve endings than anywhere else in the
body
Protection to the eye
The only part of the eye that is transplanted from
one person to another
7.
8.
9. Aqueous humor
Fills space between cornea and iris
Continuously produced by ciliary body
Flows into ant chamber through the pupil
Drains from eye through trabecular meshwork to canal of
schlemm
Nourishes the cornea and lens
Gives front of eyeball form and shape
Anterior chamber is area between the cornea and the iris: filled
with aqueous
Posterior chamber is the area behind the iris and in front of the
lens: filled with aqueous
10.
11.
12. Limbus
Junction between the cornea and the sclera
Nourishes peripheral cornea…assists in corneal
wound healing
Pathway for aqueous outflow (contains trabecular
meshwork and canal of schlemm)
13.
14.
15. Conjunctiva
Thin translucent mucous membrane starts at the
limbus and covers the sclera and inner surface of
the eyelid
Has some responsibility of tear production
Subject to infection…problems from contact lens
use
Can be degraded by environmental conditions
heat, wind, dust, etc.
16.
17. Sclera
White of the eye
Made up of 3 layers
Tough, fibrous tissue: site of extra-ocular muscle
attachment
Opaque...allows no light to enter
Subject to inflammation
18.
19. Iris
The colored part of the eye…unique to every individual
like a fingerprint
Color is dependent on the amount of pigment
A diaphragm, the iris has tiny muscles that control the
light levels in the eye
Has 2 layers
Pupil is located in the center of the iris
pupil = hole: it is not an eye structure
20.
21.
22. Lens
Transparent, biconvex structure, held in place by ciliary
zonules
Composed of 6 layers
Refracts light
Nutrition comes from aqueous humor…insoluble deposits
of proteins build up over time = cataracts
A clouding of the lens and capsule
Live long enough and you WILL have some degree of
cataract
cataracts also caused by other agents
23.
24. Ciliary body
Connects the choroid with the iris
Has three parts including:
The ciliary muscle is ring shaped muscle that controls
the shape of the lens (accommodation)
The ciliary process is the attachment site for the
zonules and produces the aqueous in the pars plicata
The ciliary ring is attached to the choroid and is
composed of the pars plana. The pars plana has no
known function in the post-fetal eye thus this is a safe
area through which surgical instruments may be
inserted
25.
26. Zonules
Attach the lens to the ciliary body
May become broken or stretched causing the lens to
move out-of-place
27.
28.
29. Vitreous
A thick, transparent gel like substance that fills the
center of the eyeball, giving it form and shape
A canal runs through the vitreous from optic disc to
the lens. It is a developmental leftover from the
hyaloid artery. Usually regresses but may persist and
result in floaters
May see reference to hyaloid membrane. This
transparent tissue surrounds the vitreous and
separates it from the retina
Central retinal veins and arteries extend in bundles,
exit and enter respectively through the optic nerve
30.
31. Choroid
A brown vascular sheet lying between the sclera and
the retina
One of the route of blood supply for the retina
32.
33. Retina
Most internal layer of eye, facing the vitreous
Converts light energy into electrical energy which is then
sent to the brain via the optic nerve
Composed of 10 layers…contains photoreceptors: cones,
near center (responsible for seeing detail and color) and
rods, in periphery (responsible for seeing in low light and
seeing movement)
Point of sharpest vision is in the fovea; located in the
center of the macula
34.
35. Ora Serrata
A serrated juncture between the retina and ciliary
body marking the transition between non-sensitive
tissue and the retinal portion with many layers and
specialized photoreceptor cells
36.
37. Intra-ocular muscles
Purpose is to move eyes
Maintain binocularity
6 muscles
medial rectus (MR)—moves the eye toward the nose
lateral rectus (LR)—moves the eye away from the nose
superior rectus (SR)—primarily moves the eye upward and
secondarily rotates the top of the eye toward the nose
inferior rectus (IR)—primarily moves the eye downward and
secondarily rotates the top of the eye away from the nose
superior oblique (SO)—primarily rotates the top of the eye
toward the nose and secondarily moves the eye downward
inferior oblique (IO)—primarily rotates the top of the eye away
from the nose and secondarily moves the eye upward
38.
39. Optic Nerve
Purpose is for energy transmission to brain
Subject to underdevelopment, damage, inflammation
Contains over 1 million nerve fibers…once severed cannot
be reconnected=no “eye transplant”
Upon examination only the head can be seen by doctor.
Should appear as yellowish pink, flat and with distinct
margins
The cup to disc ratio is evaluation as a measure of health…
increase in size of cup may indicate elevated pressure
40.
41. Optic Nerve Pathways/Visual Cortex
Message is carried down the optic nerve through pathways
to occipital cortex; here vision becomes sight
At the optic chiasma, the nasal nerve fibers cross;
temporal nerve fibers go straight back to cortex; this
arrangement impacts on visual fields
Results in visual field losses can be predicted based on
where damage is located on the optic nerve