Topic 8.4 Flashcards
Fibrous layer of the eye
Sclera + cornea
What is macula lutea?
Zone with high density of photoreceptors and fovea centralis in the middle
What is the zonula of the eye?
Connection between ciliaris and lens
Type of vision of rods
Scotopic vision
Type of vision of cones
Photopic vision
What is the combination of the 2 vision?
mesotopic vision
What is the refractive index?
Measure of the speed of light within a substance
Innervation of lateral rectus
CN VI
Innervation of superior oblique
CN IV
Innervation of most of the extraocular muscles
CN III
Refractive power of the cornea
48D
refractive power of the lens
20-30D
Mechanism of distant vision (4 steps)
- Ciliary muscle relaxes
- Zonula tenses
- Lens flattens
- Increase focal length, increase D
Accomodation triad for near vision
- Lens accommodation
- Convergence of the eyes
- Miosis (pupils constrict)
Efferentation of accommodation through EW (4)
EW - ciliary ggl - PARAS - ciliaris, papillary sphincter
Efferentation of accommodation through oculomotor nucleus
directly to extraocular muscles (except LR and SO)
What is normal vision called?
Emmetropia
What is farsightedness called?
Hyperopia / hypermetropia
What is presbyopia?
farsightedness due to loss of elasticity
What produces aqueous humor?
ciliary processes
Resorbtion of aqueous humor?
Canal of schlemm
Resorption of vitreous humor?
filtration at retinal vessels
Roles of aqueous humor? (2)
- keeps anterior chambre pressurized
- maintenance of the eye’s shape
Roles of vitreous humor? (2)
- Physical support for the retina
- Maintenance of the eye’s shape
Which chart do we use to measure VisAc
Snellen chart
5 types of neurons in the retina
- photoreceptors
- ganglion cells
- bipolar cells
- horizontal cells
- amacrine cells
Which cells of the retina generate an AP for CN II?
ganglion cells (ONLY ONES!)
Role of bipolar cells
connect photoreceptors and ganglion cells radially
Role of horizontal cells
Interconnect photoreceptors and bipolar cells
Role of amacrine cells
Interconnect bipolar cells and ganglion cells
10 layers of the retina
- Pigmented epithelium
- Photoreceptor layer
- Outer limiting membrane
- Outer nuclear layer
- Outer plexiform layer
- Inner nuclear layer
- Inner plexiform layer
- Ganglion cells layer
- Nerve fibre layer
- inner limiting membrane
What forms the limiting membrane?
The Müller cell
Where are rods mostly located?
Densely at the periphery of the retina, except in fovea and optic disc
Where is the density of cones highest?
At the fovea
3 subtypes of cones
- blue (short, 419nm)
- green (medium, 533nm)
- red (long, 564nm)
3 layers of the eye
- fibrous
- vascular
- retina
