Eye Flashcards
What liquid fills the anterior chamber?
Aqueous humor
What is the function of aqueous humor?
Maintain the shape of cornea - by pressure
A source of nutrients for non - vascular lens and cornea
What is conjunctiva?
Thin mucous membrane lining the posterior surface of each eyelid and covers the sclera - contains goblet cells
What is the function of conjunctiva?
Lubrication of the eye by producing mucus and tears
Prevents entry of microbes to the eye
What is the function of sclera?
providing attachment for the extraoccular muscles that move the eyeball
What is the sclera?
A fibrous protective outer layer of eye containing collagen and elastic fibres
What is the function of the iris?
Control diameter and size of pupil - fibres are under autonomic control
What type of iris fibres constrict the pupil and reduce the amount of light falling on the retina?
Circular fibres
What is the function of radial fibres?
Dilate the pupil - increasing the amount of light falling on the retina
What innervates the circular fibres of iris?
The oculomotor nerve
What innervates the radial fibres?
Superior cervical ganglion
What are the results of contraction of ciliary body?
The lens become rounder focusing on nearer objects
What are the results of relaxation of ciliary body?
Causes the lens to flatten focusing on distant objects
Where does reabsorption of aqueous humor occur?
Ciliary body
What can problems of drainage of aqueous humor lead to?
Glaucoma - can damage the optic nerve which can lead to progressive loss of vision
What are three function of the choroid layer?
- Contain a dark pigment that absorbs light and reduces reflection
- Highly vascular so nourishes outer layer of retina
- Regulates retinal heat - assists in controlling intraocular pressure
What is the name given to cloudy patches in the lens that make vision blurred or misty?
Cataracts
What is the most posterior compartment of the eye?
The retina
What is contained in the retina?
Photoreceptors
First and second order neurons of the visual pathway
What are the 2 layers in the retina?
- outer cell pigment layer - single layer of cuboidal epithelial cells with melanin filled microvilli extending from their inner surface
- A multilayered neural retina
Are there more rod cells in the retina or cones?
Rods
What type of vision are Rods involved in?
Black and white
What type of vision are cones involved in?
Colour
Which has higher activity cones or rods?
Cones
Which is more abundant at macula cones or rods?
Cones
what does optic disk swelling cause?
Papilloedema
What is papilloedema a sign of?
Raised intracranial pressure
What is the fovea?
Point on the retina at which the image of the object at centre of visual axis falls
How is the fovea specialised for visual activity?
Only cones are present
light sensed without dispersion
Hexagonal mosaic of cone cells
Where are blood vessels that supply the retinal cells found?
In the choroid
What is detached retina?
Retina begins to pull away from blood vessels that supply it with oxygen and nutrients - can lead to blindness
