Download eye

Stefan Sivkov, MD, PhD
Development
А. Onset 22 day of gestation; from neuroectoderm,
ectoderm & mesoderm.
B. Diencephalic vesicle gives origin to optic vesicle; after
invagination develops double-layered optic cup.
i) Inner layer develops into в pars nervosa of retina
ii) Outer layer gives pars pigmentosa of retina, pigmentous
epithelium of iris and ciliary body.
C. Ectoderm gives origin of :
i) Lens.
ii) Corneal epithelium and conjunctiva.
D. Mesoderm gives origin of:
i) Stroma of sclera and cornea.
ii) Stroma of choroid.
Development
Three parts

Optic apparatus – controls the light entering the eye

Detector system – for black / white and color vision

Nerve pathways – conveys signals to brain
Eye ball
3 coats
Tunica Fibrosa:
cornea, sclera
Tunica Vasculosa:
choroidea, corpus ciliare, iris
Tunica Nervosa:
retina
3 chambers
Anterior eye chamber
Posterior eye chamber
Corpus vitreum
Tunicae bulbi
Outer, tunica fibrosa bulbi
- cornea (transparent)
- sclera (non-transparent, bluish in children, yellowish in adults)
Middle, tunica vasculosa bulbi
- iris and central opening, рupilla
- corpus ciliare composed of: musculus ciliaris, processus ciliaris,
zonula ciliaris with fibrae zonulares & spatia zonularia
- choroidеа
Inner, tunica interna bulbi (retina)
- blind part, рars caeca retinae (from мargo pupillaris iridis to оra
serrata):
Pars iridica retinae (double-layered, pigmented cells)
Pars ciliaris retinae (double-layered, pigmented inner layer)
- рars optica retinae (stratified)
Eye chambers
Three chambers filled with fluid:

Camera anterior bulbi (between cornea & iris),

Camera рosterior bulbi (between iris, fibrae zonulare & lens)

Corpus vitreum (between lens & retina).
The nfirst two filled with humor aquosus,
Corpus vitreum filled with humor vitreus.
Tunica fibrosa
Sclera
Posterior 4/5 of tunica fibrosa;
Collagen & elastic fibers, fibroblasts (substantia
propria sclerae),
3 layers:
 episclera: outer
 substantia propria sclerae: middle
 lamina fusca: inner, collagen & elastic fibers
pigment cells; borders choroid
Cornea
А. Anterior 1/5 of the coat
Б. 5 – layered:
- Epithelium anterius: squamous stratified
nonceratizing, 5 - 6 layers:
- Lamina limitans anterior (Bowman): 7 -12 mcm,
collagen fibers, lacks cells, barrier agains infection,
does not regenerates.
- Substantia prоpria: 200 laminae of parallel collagen fibers.
- Lamina limitans posterior (Descemet): 5 - 10 mcm, basal lamina
of endothelium.
- Endothelium posterius: simple squamous epithelium
i) Avascular
ii) Transparent
iii) Limbus - connection with sclera:
Highly vascular
Contains sinus venosus sclerae
(Schlemm canal)
Tunica vasculosa
Three parts:
1. Posterior - сhoroidea
2. Middle - сorpus ciliare
3. Anterior - iris
Choroidea


2/3 of the coat
Attached posteriorly to the sclera
– Spatium perichoroidale
– Lamina suprachoroidea

Composed of:
– Connective tissue
– Pigment cells
– Blood vessels

3 layers:
– Lamina vasculosa
– Lamina choriocapillaris
– Lamina basalis (Bruch)
Choroidea
Corpus ciliare


Orbiculus ciliaris – posterior
Corona ciliaris - anteromedial
– Processus ciliares (70-80)

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Dense capillary network
Produce humor aquosus
Fibrae zonulares
Musculus ciliaris - lateral


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Fibrae meridionales (Brucke)
Fibrae radiales
Fibrae circulares (Muller)
– Takes part in (n. oculomotorius)
Coprpus ciliare
Orbiculus ciliaris, corona ciliaris
Accomodation

Focusing for near vision

Contraction of the pupil

Convergence
Accomodation

M. ciliaris contracts and moves
forward

That relaxes zonule ciliares and
lens becomes more convex

The eye adapts to near vision
Iris

Color is genetically determined.

Pigment:
а. melanin & b. lipochrome.

Melanin - gene of 15 chromosome.

Lypochrome - gene of 19 chromosome.
Iris



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Anterior part
Opening in the middle, pupilla.
Margo pupillaris & margo ciliaris
Annulus iridis minor & anulus iridis major
Structure
– Epithelium anterius
– Stroma iridis
– M. sphincter & dilatator pupillae
– Epithelium pigmentosum
Attached to the sclera by lig. pectinatum
Iris. Ligamentum pectinatum
Retina




Eye fundus discus nervi optici (2 x
1.5 mm), central - excavation.
4 mm lateral is an oval spot, fovea,
in the center of macula lutea.
Centarl part of retina – d=21 mm
from the center of discus n. optici .
Diameter of retina - 42 mm.
Structure

Retina (0.5 mm) inner layer.

N. opticus – axons of the ganlion cells.

Ganglion cells, efferent, the innermost.

Photoreceptive cells, rod and cones, outer.
RETINA
1. Pars pigmentosa
- detachment of retina
2. Pars nervosa
(1) Stratum neuroepitheliale
Bacillus, Conus
(2) Stratum nucleare externum
Bipolar cell
Horizontal cell
Amacrine cell
(3) Stratum nucleare internum
Ganglion cell
Nervus Opticus (II)
Structure of retina

Three cellular layers
Outer nuclear – bodies of rods & cones
Inner nuclear – bodies of bipolar,
horizontal & amacrine cells
Ganglion – bodiesa of ganglion cells.

Two synaptic layers
Outer plexiform
Inner plexiform
Synaptic layers
Stratum plexiforme externum
Stratum plexiforme internum
Ora serrata.
Pars optica & pars ceca retinae
Fovea centralis
Rods and cones
Optic nerve
Visual
Pathway
Visual Pathway
Modality: Vision
Receptor: Photoreceptor Cell of Retina
Cranial Nerve: II (Optic nerve)
1st Neuron: Bipolar Cell
2nd Neuron: Ganglion Cell
optic nerve
optic chiasm
optic tract
3rd Neuron: Lateral Geniculate Nucleus
optic radiation
Termination: Primary Visual Area (V I)
Brodmann area 17
Visual Pathway
1. Optic nerve
2. optic chiasm
3. optic tract
4. lateral geniculate body
5. optic radiation
6. visual cortex
(striate cortex)
7. Meyer’s loop
8. lateral ventricle
Visual
Pathway
1. Optic nerve
2. Optic chiasm
3. Optic tract
4. Lateral geniculate
body
5. Optic radiation
6. Visual cortex
(Striate cortex)
Clinical Features of Visual Pathway Lesion
1. optic nerve
2. optic chiasm
3. optic tract
4. 5. optic radiation
A. unilateral blindness
B. bitemporal hemianopsia
C. left homonymous
hemianopsia
D. left inferior homonymous quadranopsia
E. left superior homonymous quadranopsia