M8IQ4-5- Technologies and Disorders Eye - Coggle Diagram
M8IQ4-5- Technologies and Disorders
visible light is a kind of electromagnetic radiation
light waves can have different amounts of energy.
high energy = purple, low energy = red, other colours = in between
when light comes into contact with an object, it's either absorbed or reflected. eyes detected reflected light rays.
reflected rays enter eye through pupil > pass through the lens > detected by photoreceptors in the retina > nerve impulse is generated and sent via optic nerve to brain.
transparent, biconvex protein disc, has a bulging shape
adjusts its thickness to bend light so that it focuses directly onto the retina
; the process in which the lens changes shape to maintain a clear focus on objects varying distances.- light rays from
objects are nearly parallel, so require little bending to be focused
light rays from
objects require more bending to be focused
thin layer of photoreceptor cells, which lines the inner back surface of the eye
photoreceptors are specialised neurons that contain photopigments (light-sensitive pigments)
don't detect colour, and work best at low light levels
detect colour and work best during the day
light passes through pupil, lens, and jelly-like fluid > hits photoreceptor cells on retina > when photoreceptor cells are exposed to light, their photopigments change shape > photoreceptor cells generate an electrochemical signal that is sent to the brain to be interpreted
ring of pigmented muscle tissue
works to control pupil size and the amount of light entering the eye
helps us deal with light at different intensities.
can damage photoreceptors in the eye (pupil constricts), and
means photoreceptors aren't being stimulated and an image can't be formed (pupils dilate).
: contains ciliary muscle. makes the clear fluid that fills the space between the cornea and iris.
: muscle that changes the shape of the lens when the eye focuses.
: provides metabolic nutrient requirements of the lens, coordinates eye growth and provides support to the retina
: where the optic nerve and blood vessels leave the eyeball. carried images to the brain.
: transmits electrical impulses from eyes to brain. brain processes this sensory information so that you can see.
: supply oxygen and nutrients to outer retina, light absorption, thermoregulation, modulation of intraocular pressure.
: maintains eyeball shape and protects it from injury. covered by conjunctiva.
: provides protection and lubrication of the eye by the production of mucus and tears.
: provides nutrition to the eye, as well as maintains the eye in a pressurised state
: protects structures inside the eyes, contributes to the refractive power of the eye, focuses light rays with minimum scatter and optical degradation.
: holds the lens in position.
caused by distortion or absence of the fovea (central, most sensitive part of the retina)
: gradual loss of central vision
: abnormal growth of blood vessels under the retina > leads to fluid leakage and sudden loss of vision
occurs when one of the three types of colour-detecting cone cells is absent or doesn't function properly
affects both eyes
damage to the retina, often caused by changes to the blood vessels in the region
light is not being properly bent onto the retina, so that vision is blurred
: distant objects clearly, close objects out of focus
lens is too thin,
not bending light enough
eyeball is too short or poor accommodation ability of the lens, causing light rays from
distant objects to be focused behind rather than on the retina.
: close objects clearly, distant objects are out of focus.
lens is too thick,
bending light too much
eyeball is too long, causing light rays from
distant objects to be focused in front of the retina
rather than on the retina.
a thin flap of the cornea is cut and lifted up > a laser (high-energy light beam) is used to reshape the cornea to a more suitable shape > the fold of the cornea is then folded back into place, and it rebonds itself.
in myopia, the curvature of the cornea is decreased, in hyperopia, the curvature of the cornea is increased.
have lenses which are shaped in order to correct individual needs, compensating for misshapen eye lenses or eyeballs, hard to use when active
cause light rays to bend before entering the eye so the image focuses on the retina
contact lenses work the same, they're just put directly on the eye, but fiddly to put in and take out
can be corrected with
(curved inwards) lenses worn for distance viewing.
these lenses cause parallel rays to
slightly before they enter the eye so that the lens can focus an image on the retina.
(bulging outwards) lenses worn for viewing close objects. these cause parallel light rays to
slightly before entering the eye so that the image can be focused on the retina.