The eye and vision Flashcards
What are the 3 layer of the eye?
Outer (Sclera and Cornea)
Middle (Uvea)
Inner (Retina)
What is the sclera?
Tough fibrous outer coat, made up of collagen
What is the cornea made up of?
Collagen
What feature of the outer layer of the eye allows light transmission?
Transparent
What is the outer layer responsible for?
2/3 refractive power of the eye
What are the 5 layered structure of the outer layer of the eye?
Epithelium
Bowman’s Layer
Stroma
Descemet’s Layer
Endothelium
What is the middle layer of the eye made up of?
Iris
Ciliary body
Choroid
What is the iris?
Coloured part at the front of the eye
What does the iris contain?
Dilator and sphincter pupillae muscles
What type of reflexes does the iris have?
Pupillary reflexes
What is the ciliary body?
Glandular epithelium produces aqueous humour
What does the ciliary muscle do?
Controls accommodation
What type of muscle is the ciliary muscle?
Smooth muscle
What is the choroid?
A thin layer of tissue that is part of the middle layer of the wall of the eye, between the sclera and the retina
What is the function of the choroid?
Filled with blood vessels that bring oxygen and nutrients to the eye, supplies blood to the outer third of the retina
What does the inner layer of the eye contain?
Retina
What process takes part in the inner layer of the eye?
Phototransduction
What structures are found in the retina?
Macula lutea
Fovea centralis
Cones
Rods
What is the macula lutea?
The part of the retina that is responsible for sharp, detailed central vision
What is found in abundance in the macula lutea?
Cones
What is the fovea centralis?
A small depression within the neurosensory retina where visual acuity is the highest
What are cones?
Photoreceptor cells that give us our colour vision
What are rods?
Photoreceptor cells in the retina that are sensitive to light levels and help give us good vision in low light
What types of cells make up the retina?
Retinal photorecptors
Bipolar cells
Amacrine & horizontal cells
Mullers glial cells
Retinal ganglion cells
What are retinal photoreceptors?
Rods and cones
Primary neurosensory cells that convert light into an electrochemical message that can be interpreted by the CNS
What are bipolar cells?
One of the main retinal interneurons and provide the main pathways from photoreceptors to ganglion cells
What are amacrine cells?
Intrinsic interneurons of the inner retina representing the most diverse class of neurons in the retina
What are horizontal cells?
Modulate the output of photoreceptors and play many roles in early visual processing contributing to:
Contrast enhancement
Colour opponency
Generation of centre–surround receptive fields in cones and bipolar cells
What are the mullers glial cells?
The principal glial cell of the retina.
They form architectural support structures stretching radially across the thickness of the retina and are the limits of the retina at the outer and inner limiting membrane, respectively
What are the retinal ganglion cells?
Bridging neurones that connect the retinal input to the visual processing centres within the central nervous system