1b Visual System Flashcards
(137 cards)
What is the palpebral fissue?
The line of the eye where the eyelashes sit
What is the limbus?
The border between the cornea and the sclera
What is the caruncle?
The inner most fleshy corner part of the eye
What is the medial canthus?
Where the caruncle meets the sclera
What is the conjunctiva?
Thin, transparent tissue which covers the outer surface of the eye
What are the three layers of the eye?
Sclera - hard and opaque
Choroid - pigmented and vascular
Retina - Neurosensory tissue
What is the sclera?
The white of the eye - tough and opaque tissue which serves as the eyes protective outer coat
What is the water content of the sclera?
High
What is the cornea?
The transparent, dome-shaped window covering the front of the eye.
What is the water content of the cornea like?
Low water content
What is the function of the cornea?
Powerful refracting surface, providing 2/3 of the eye’s focusing power. Like the crystal on a watch, it gives us a clear window to look through
What happens if the cornea becomes hydrated?
becomes cloudy
What is the uvea?
Vascular coat of eyeball and lies between the sclera and retina.
What are the three parts of the uvea called?
Composed of three parts – iris, ciliary body and choroid.
What is the choroid?
Choroid - lies between the retina and sclera. It is composed of layers of blood vessels that nourish the back of the eye.
What is the function of the iris?
Controls the amount of light which is entering into the eye - has tiny muscles which dilate and constrict the eye
What is the structure of the lens?
It is composed of an outer acellular thin capsule,
encasing a core of regular elongated cell fibres.
What percentage of the eyes refractory power comes from the lens?
1/3 of the eye focusing power - higher refractive index than aqueous fluid and vitreous
What is a cataract?
The lens may loose its transparency with age,
resulting in an opaque lens, known as Cataract.
What is the retina?
Thin layer of tissue which lines the inner part of the eye
Responsible for capturing the light rays which enter into the eye - light impulses are then sent to the brain for processing via the optic nerve
What is the function of the optic nerve?
Transmits electrical impulses from the retina to the brain
What is the visible portion of the optic nerve called?
The optic disc
Where does the optic nerve connect to the back of the eye?
Near the macula
What is the blind spot?
Where the optic nerve meets the retina, there are no light sensitive cells