Parts/Functions of the Eye
What is the SCLERA ?
the tough, white, outer layer of the eye that provide structure and protects the inside of the eye
MYOPIA is also known as ______
Nearsightedness
Describe the function of the PUPIL
Controls how much light enters the eye (through contraction and dilation)
Light enters the eye through a clear portion of the ______ (tough, white, outer portion of the eye), called the ______.
Sclera, Cornea
What path does light take as it enters through your eye?
Light enters the eye through the cornea, which bends it toward the pupil, where the iris adjusts its size to control the amount of light allowed in. The light then passes through the lens, which further focuses it onto the retina at the back of the eye. The retina’s photoreceptors (rods + cones) help convert the light into electrical signals, which travel via the optic nerve to the brain for processing.
Describe the appearance AND function of the IRIS
the coloured part of the eye, muscle around pupil that expands or contracts to adjust the size of the pupil
HYPEROPIA can be corrected with a ______ lens
Convex, because light doesn't refract enough when passing through the focusing mechanism, or the eyeball is too short from front to back, meaning the image is formed before the retina instead of ON the retina.
On what part of the eye is an image formed?
What is a CATARACT, and how does it affect the eye?
A cataract is clouding of the lens. It usually occurs after age 40, and it prevents light from getting through properly, which can cause blurry to hazy vision, diminished colour perception, poor night vision, etc.
Why are two eyes better than one?
Two eyes improve depth perception because each eye sees a slightly different image, and the brain combines them to judge distance accurately. They also enhance peripheral vision, allowing a wider field of view and better awareness of movement. This binocular vision (seeing through two eyes) helps with tasks like catching a ball, driving, and navigating complex environments.
What is the VITREOUS HUMOUR ?
jelly-like substance inside the eye that gives the eye shape
PRESBYOPIA is ____ and is caused because of _____
The inability to focus on nearby or faraway objects, and is caused because the lens and cornea lose some of their elasticity overtime, and cannot change shape as easily. It is typically an age-related vision defect.
How do CILIARY MUSCLES control the focus of objects?
They control the focus of objects by adjusting the shape of the lens through a process called accommodation. The ciliary muscles contract to focus on nearby objects (the lens becomes thicker and more curved), and they relax to focus on far away objects (the lens becomes thinner, flatter, and less convex)
What is HUD? Describe it in a sentence or two.
HUD (Heads Up Display) is technology that projects information on a transparent screen, allowing users to view key data without diverting their attention.
What is the name of Mr. L's field advisor, who he introduced at the beginning of class?
Ms. Jost
What are the 2 types of light sensitive cells that are present in the retina, and what do each of them detect?
Rods (low light, black and white) + Cones (colour)
Describe one PRO and one CON for LASIK surgery
PROS - light sensitive for only 4 hours, vision is excellent after just 24 hours, it is the fastest recovery
CONS - more invasive, risk of dry eye for up to a year
What do the CORNEA and LENS have in common?
They both are responsible for refracting/bending light to focus it onto the retina
Why are NEW artificial lenses better than OLD ones?
Older artificial lenses were made from more rigid materials and therefore were more complicated to implant in the eye. Also, they did not accommodate focusing at different distances.
Newer lenses are easier to be inserted during surgery due to them being made from more flexible materials, and most importantly, they offered accommodation options, allowing for better vision at different distances.
What does Mr. L's girlfriend do for her job?
She is a teacher as well!
What is the BLIND SPOT? Explain where it is located and why it is called the blind spot.
The blind spot is located at the optic disk, which is where the optic nerve exits at the back of the eye. It is a blind spot because it LACKS light sensitive cells (rods and cones), therefore it does not have the ability to detect visual information. This absence of rods and cones creates a small gap in the visual field. Our brain fills in any missing information cause by the blind spot.
What is the MAIN difference between PRK and LASIK surgery?
With PRK, no flap is cut, and they remove tissue directly from the surface of the cornea.
What is the function of the OPTIC NERVE? You may use an example to describe what it does.
Transports the electrical signals created by the retina, to the brain for interpretation. It is like a data cable that transfers information.
What does it mean to have NORMAL VISION?
Normal vision, aka 20/20 vision, means a person can clearly see at 20 feet what the average person should be able to see at that distance, as measured by the Snellen chart. If a person has 20/40 vision, for example, it means they must be 20 feet away to see what someone with normal vision can see from 40 feet.
NOT including this one, how many weeks has Mr. L already spent here at Lansdowne during his practicum?
7