sciencee

what is the eye diagram

define sclera

tough, opaque outer coating layer of the eye

function- the 6 tiny muscles are connected which controls the eye’s movements

define choroid

a highly tough, pigmented vascular layer between the sclera and retina

function- contains blood vessels that provide oxygen and nutrients, mostly photoreceptors

define retina

the light sensitive part of the eye, covered in light receptors called rod and cones

function- specialised cells catch light photons and convert into electrical impulses.

define optic disc (blind spot)

where the optic nerves leave the retina theres no rods and cones

function- serves as gateway where over 1 million retinal cell axons converge and exit the eye.

define optic nerves

carries impulses from the light receptors to the brain

function- transmits sensory data to trigger autonomic reflexes

define cornea

clear, dome-shaped outer surface covering the front of the eye

function- provides two-third of the eye's focusing power and refracts light to the ear

define iris

a coloured, ring-shaped muscular membrane

function- changes the size of pupil to control how much light enters the eye

define aqueous humour

jelly-like substance thats found between the cornea and lens

function- supplies oxygen, glucose and acids to avascular structures like cornea and lens

define suspensory ligaments

controls the shape of lens with the ciliary muscles

define ciliary muscles

controls the shape of lens with the suspensory ligaments

define pupil

black, circular opening located in the centre of the iris

function- changes size to manage light entering the eye, protecting the inner structures in bright environments

define lens

flexible, biconvex structure located directly behind the iris and pupil

function- provides one-third of the eye's total focusing power of the cornea

define vitreous humour

jelly-like substance thats found between the retina and lens

function- exerts outward pressure to keep the eyeball spherical and prevents it from collapsing

explain the path of light through the eye

Cornea → Aqueous Humour → Pupil/Iris → Lens → Vitreous Humour → Retina, which transmits signals to Optic Nerve and the brain

why is the eye called a sense organ

contains specialised sensory receptors that detect physical stimuli from the environment

what gives people different eye colours

amount and type of melanin pigment in front layers of iris

what happens to lens when viewing a nearby object

the lens of the eye undergoes a process called accommodation becomes thicker, more curved and the ciliary muscles contract

what happens to lens when viewing a distant object

the lens of the eye undergoes a process called accommodation becomes thinner, more flatter and the ciliary muscles relax

why does the lens change thickness

to shift focus between objects that are close by and objects that are far by

define photoreceptors

specialised neurons in the retina at the back of the eye that convert light energy to electrical signals

difference between rod cells and cone cells

rod cells- enables vision in low-light conditions but cant detect colours, low resolution, back and white

cone cells- requires bright light to function and responsible for high resolution with colour vision

what do rod cells detect

colour wavelength, fine details and rapid changes on light

what do cone cells detect

low-intensity light, shapes and motions in dark environments

where are rods and cones mainly found in the retina

Rods: spread throughout the peripheral retina outside the central zone

Cones: highly concentrated in the fovea centralis in the central retina

define fovea

a tiny, specialised depression in the centre of the retina that provides our sharpest, most detailed vision

define myopia and how its treated

condition in which close objects appear clearly, but far away objects are blurry.

how its treated- eyeglasses, contact lenses with negative lens, laser surgery to change the cornea or lens

define hyperopia and how its treated

condition in which far away objects appear clearly but nearby objects are blurry.

how its treated- eyeglasses, contact lenses with positive lens, laser surgery to change the cornea or lens

define astigmatism and how its treated

common imperfection in the curvature of the eye’s curvature

how its treated- special astigmatism eyeglasses, contact lenses, laser surgery to change the cornea or lens

define cataracts and how its treated

clouding in normal clear lens of the eye, resulting in blurry vision

how its treated- replacing the cloudy lens with a clear, artificial lens.

why do cataracts cause blurry vision

the clumped proteins inside the eye’s natural lens scatter and block light rays

define glaucoma and how its treated

clouding in normal clear lens of the eye, resulting in blurry vision

how its treated- eye drops, medications to reduce eye and blood pressure, laser surgery to remove tissue

define colourblindness and how its treated

A reduced ability to distinguish between certain colors.

how its treated- no treatments

define macular degeneration and how its treated

Deterioration of the center of the retina causing central vision loss.

how its treated- special combination of vitamins and minerals and surgery

difference between concave and convex lens

(myopia) concave- diverges light rays so that they are further apart

(hyperopia) convex- converges light rays so that they are further apart