Vision & the eye Flashcards
Describe the 3 coats of the eye.
Outer
- cornea
- sclera
Middle (uvea)
- iris
- ciliary body
- choroid
Inner
-retina
Describe the outer coat and its contents.
SCLERA
- White capsule
- Insertion for muscles
- Protection, tough outer collagen layer
CORNEA:
- Clear part
- Transmission of light
- Refraction
- Transparent, smooth & spherical
Describe the middle coat and its contents. What is the name of the middle coat?
Uvea
IRIS
- iris colour
- pupil & reflexes
- sphincter & dilator muscle
CILIARY BODY:
- glandular = production of aqueous humour, nutrients for cornea & lens, maintains intraocular pressure
- smooth muscle = controls accommodation (eyes moving at same time)
CHOROID:
- nutrition of outer retina
- absorbs stray photons
What are the layers of the retina? External to internal.
10 layers
Retinal pigment epithelium Photoreceptor External limiting membrane Outer nuclear Outer plexiform Inner nuclear Inner plexiform Ganglion cell Nerve fibre Internal limiting membrane
What features can you see on an ophthalmoscope?
Macular lutea - blood vessel free region at centre
Fovea centralis - central shallow pit with many cones
Optic disc - centre of all nerves
Name the two types of photoreceptor cells?
Rods
Cones
Where are photoreceptor cells found?
Retina
What vision do rods do?
Night vision
What vision do cones do?
Day and colour
Describe the layers from rods/cones to nerve fibre layer.
Rods/cones Horizontal cells Bipolar cells Amacrine cells Ganglion cells Nerve fibre layer
What are the muscles of the eye?
Top: superior rectus
Sides: Lateral rectus &
Medial rectus
Bottom: Inferior rectus
Sideways top: Superior oblique
Sideways bottom: Inferior oblique
Controls eyelid: Levator palpebrae superioris
What nerve supplies the superior rectus?
Oculomotor
What nerve supplies the Inferior rectus?
Oculomotor
What nerve supplies the lateral rectus?
Abducens
What nerve supplies the medial rectus?
Oculomotor
