This is about the most important organ of the visual system. Here, the structures of the eye and how it works are explained.

1. THE EYE
RAHAF ALMATROOK

2. What Is It?
• Eyes are organs that are used in the visual system.
• They can identify light and convert them into electro-chemical signals.
• There are some organisms that have eyes that can detect light from far away, such
as eagles. Other organisms can only detect whether there is light present or not,
without imaging.

3. Location
The eyes are located in the orbital fracture of the skull. (the eyes sockets)

4. Parts of the eye
• The Sclera: the white part of the eye.
• The Cornea: it is a clear surface on top of the Iris, Pupil and Sclera.
• The Anterior Chambers: the space in between the Cornea and the Iris.
• The Posterior Chamber: the space in between the Iris and the Lens.
• The Pupil: A hole where light enters the eye.
• The Iris: The pigmented ring around the pupil which controls the size and shape of
the pupil.
• The Lens: is a transparent body that has layers (like an onion) which changes its
shape to focus images.
• The Vitreous Humor: a Gelatin-like substance that fills the space between the lens
and the retina.
• The Retina: is a thin membrane that is located next to the optic nerve so that when it
receives light, it can convert it into electro-chemical signals to be sent to the optical
nerve of the brain.
• The Conjunctiva: are thin membranes that
connect the eyes to the eyelids

5. Then what’s wrong with
blind people’s eyes?
Blind people have two main causes of being
blind which are:
• Diseases that ruin the eyesight gradually
• Genetics passed down
• A problem with the optic nerve
• A absence of the Retina.
That is why the retina is very important. It
is the main cause for blindness is people.
If it is absent, then there will be no
conversion of light into electro-chemical
signals that can be converted into images;
therefore, they are blind.

6. How does the eye
function?1. Think of a camera when you think of the eye. The lens of the camera
is also the lens of the eye, they both work the same way. This is where
light is focused.
2. The iris acts as the diaphragm of the camera, which adjusts the size
of the pupil, and the focus.
3. The lens focuses the light further when the eye is looking at
something in particular, kind of like when you focus on a camera. This
is the process of accommodation. This helps the eye focus
automatically, like auto-focus in a camera.
4. The light reaches the retina, which acts as the film of the camera, and
it is then converted into electro-chemical signals, which are then sent
to the optic nerve in the brain to be processed into the images we see.Imagine how fast this happens!

7. Then why do people wear
glasses?
• Nearsightedness, or myopia is when a person cannot see distant objects and
see them blurred.
• This develops when light or images are focused in front of the retina instead of
on the retina itself.
• This can also develop because of abnormal cornea or lens shape.
• Symptoms:
1. Squinting of the eyes
2. Headaches
3. Difficulty seeing

8. Diseases and
Disorders• Visual Impairment
• Macular Degeneration
• Cataract
• Retinopathy
• Conjunctivitis

9. Macular
Degeneration
This specific disease effects the retina of the eyes. But, it specifically effects the macula
of the retina, which is why the disease is named Macular Degeneration.
The macula is what further focuses the light when recognizing texts and faces. This is
the leading cause of vision loss in older adults.

10. Cause
This disease is caused because there are waste products building up under the macula.
This causes the blurring of the vision. This is called Dry Macular Degeneration.
Later on, it progresses into Wet Macular Degeneration because there is an abnormal
growth of blood vessels into the retina. This causes bleeding and changes in the
vision.
Very few people get Wet MD, but it is the only the “upgrade” of dry MD.

11. Symptoms
Symptoms may include:
• Dark Spots in the center of the eye
• Lines and grids seem like waves
• Sudden loss of centered vision
• In rare cases, colors may change

12. Stages of MD
There are 3 stages of MD:
1. Early MD: This is diagnosed by the presence of a bit of drusen,
which is the waste product building up under the macula.
2. Intermediate MD: Here, vision loss is noticeable and some pigment
may fade.
3. Late MD: Vision loss is extremely noticeable and it soon turns from
Dry MD to Wet MD.

13. Diagnosis
• A doctor will first try the eye test and may ask if you can or cannot see
in the center of your vision.
• The doctor may then proceed to inject a yellow dye in the vessels, most
commonly in the arm, where the dye will travel through the blood.
Since there is an abnormal growth of vessels in Macular Degeneration,
the dye will travel all the way to the abnormal vessels in the eye. A
special camera is used to take a shot of the vessels, if the yellow dye is
found in the eye, the Wet MD is diagnosed. However, if there is no
yellow dye, then there is no Wet MD, but rather, there might be a
possibility of having dry MD.

14. Treatments/Cures/Preve
ntionThere is no cure found yet; but, there are treatments such as:
• Laser therapy
• Anti-angiogenic drugs
You can prevent it by:
• Maintaining a healthy diet
• Avoid smoking
• Protect your eyes from UV lights.

15. • http://www.allaboutvision.com/resources/anatomy.htm
• https://www.webmd.com/eye-health/picture-of-the-eyes#1
• https://en.wikipedia.org/wiki/Eye
• https://www.nkcf.org/about-keratoconus/how-the-human-eye-works/
• https://www.everydayhealth.com/hs/managing-wet-
amd/understanding/?xid=cs_001_023_106&gclid=Cj0KCQiAl8rQBRDrARIsAEW_To8ZQcIos
1nMrsiZ0ULqPj0Wkb7stCTUrEo1n-wRe9XXpJkK2ih8-5QaAm4DEALw_wcB
• https://www.macular.org/what-macular-degeneration
• https://www.aao.org/eye-health/diseases/amd-diagnosis
• https://nei.nih.gov/healthyeyes/myopia
• https://www.cis.rit.edu/people/faculty/montag/vandplite/pages/chap_8/ch8p3.html
• https://www.healthline.com/human-body-maps/retina
• https://www.quora.com/How-is-the-anatomy-of-a-blind-persons-eyes-different
• http://www.allaboutvision.com/resources/conjunctiva.htm
• https://www.webmd.com/eye-health/macular-degeneration/age-related-macular-
degeneration-symptoms
• https://www.webmd.com/eye-health/macular-degeneration/age-related-macular-
degeneration-treatment#1
Bibliography