Visual apparatus Oculus et structurae pertinentes
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Transcript of Visual apparatus Oculus et structurae pertinentes
Visual apparatusOculus et structurae pertinentes
Morfology and embryology
Odilo Redon
Orbita
Shape of 4-sided pyramid falled backsideBony marginsaditus x apex10 openingsm. orbitalis Mülleri – smooth muscle in
fissura orbitalis inferiorcontent: eye ball, muscles, adipose tissue
and accessory organs
Orbita – bony walls
Orbita – bony walls
Surrounding structures:medially: cellulae ethmoidales (behind thin
lamina orbitalis o.e.)caudally: sinus maxillariscranially: fossa cerebri anteriordorsally: sinus cavernosus + fossa
pterygopalatina
Visual apparatus
Eye ball = Bulbus oculiAccessory apparatus = Structurae
accessoriae/pertinentes oculi Topography - regio orbitalisDevelopment of eye apparatus
Eye ball
tunica fibrosa (externa)
tunica vasculosa (media)
tunica interna (nervosa)
Vitreous body + lens cristallina
Eye ball
polus anterior, posterior
equator x meriadiani axis bulbi externus,
internus axis opticus (= „linea
visus“)
Tunica fibrosa (externa)
scleracornea
Tunica fibrosa (externa)Sclera
Thick tissue (= reticulum trabeculare), colagenous fibers, fibroblasts, basic substance
lamina episcleralis, substantia propria, lamina fusca lamina cribrosa (entrance of n. II.) 5/6 of surface, ø 2,2 cm sinus venosus sclerae (canalis Schlemmi s. Lauthi) sulcus sclerae – sclerocorneal junction = limbus corneae
(angulus sclerocornealis)
Tunica fibrosa (externa)Cornea
Totally translucent, w/o vessels limbus, vertex 5 layers
– epithelium anterius cornae (multi l. cuboid)– lamina limitans anterior (Bowmann membrane)– substantia propria corneae– lamina limitans posterior (Descement membrane)– epithelium posterius corneae („endotelium“)
11 x 12 mm – fyziological astigmatismus
Tunica vasculosa (media) = Uvea
choroid (choroidea)Ciliary body (corpus ciliare)iris (iris)
Tunica vasculosa (media) Choroidea
lamina suprachoroidea (= lamina fusca sclerae) spatium perichoroideum lamina vasculosa (choroideal stroma)
– Big vessels, tissue, smooth muscle cells, nerves lamina choroidocapillaris
– capillaries lamina basalis = Bruch membrane
– BM pigment epitelium and capillaries + tissue
Tunica vasculosa (media) ciliary body = Corpus ciliare
Shape of annulus, section of triangle
processus + plicae ciliares
orbiculus (outer part), corona (inner part)
smooth musculus ciliaris– fibrae meridionales,
radiales, circulares, longitudinales
Tunica vasculosa (media) ciliary body = Corpus ciliare stroma
– m. ciliaris: parasympaticus akomodation look close
(look remote maintains plasticity of uvea)– Capillaries and nerves supplying muscle
Epitelial cover – production of humor aquosus– BL – continuation of Bruchs membrane– pigment epitelium – (from pigment epitelium of retina)– Cilliary canal– Non pigmented epithelium (from sensory epithelium of
retina)– BL– fibrae zonulares – fixate lens
Tunica vasculosa (media)Iris
Shape of annulus, flat Function of shutter margo ciliaris (outer), m. pupillaris (inner) pupilla (= pupil) anulus iridis major + minor (contain circulus arteriosus
iridis major + minor) m. sphincter pupillae (parasymp.) – miosis (circular) m. dilatator pupillae (symp.) – mydriasis (fanwise)
Tunica vasculosa (media) Iris
plicae iridis, stroma iridis Anterior pole
– Does not have epithelial lining (stratum limitans anterius)– fibroblasts and melanocytes (color)– plica radians = serrated line – remnant of membrana
pupillaris Wachendorfi Posterior pole
– Two layers of pigment epithelium– Inner pigment– Outer myoepitelial
• m. sphincter pupillae• m. dilatator pupillae
Lens crystallina = Lens
polus anterior, posterior axis, equator, radii (sutures in Y shape and reversed
Y) capsula lentis substantia lentis – cortex, nucleus zonula ciliaris Zinni
– fibrae zonulares
– spatia zonularia
Gray cataracta - prosthesis
Lens crystallina (lens)
transparent biconvex w/o vessels capsula – similar to basal lamina Lens epithelium – single layer cuboid
– Only on anterior side of lens Lens matter
– cortical – contains elongated cells (fibers) with organels and nucleus
– nuclear – cellular fibers w/o organles and nucleus– Cells contain specific proteins (filensin, crystallins)
Acommodation
Focusing on close distance– Contraction of m. ciliaris
– fibrae zonulares relaxing
– Lens forms ball
– Together with contraction of m. sphincter pupillae (= miosis)
Focusing on remote distance– Tonus of vessels maintains fibrae zonulares extended
– Lens is flattened
– Contraction of m. dilatator pupillae (= mydriasis)
Vitreous body = Corpus vitreum
membrana, stroma, humor vitreus Composed of 99% water Hyaluronic acid, kolagen fibers cells – hyalocytes – only during development ! Does not regenerate ! – in case of injury it flows
out – exchanged by chamber fluid canalis hyaloideus Cloqueti – remnant of fetal
arteria hylaloidea fossa hyaloidea Maintains inner eyeball pressure, pushes retina
Chamber fluid= Humor aquosus
Produced by ciliary body Reabsorbed in angulus iridocornealis 0,2-0,3 ml translucent, watery fluid Daily produced cca 3 ml composition: 0,7-1,2 % NaCl, traces of urea and
glucose (0,1%), no proteins Serves as lymph Intraocular pressure 14-17 mmHg
Intraocular pressure pressure on retina glaucoma (= glaukom)
Eyeball chambers = Camerae bulbi
Vitreal chamber (camera postrema s. vitrea)– Between ciliary body, lens and retina– Contains vitreous body– spatium retrozonulare
posterior chamber (camera posterior)– Between iris, lens and ciliary body– Contains and produces humor aquosus
Anterior chamber (camera anterior)– Between cornea and iris– angulus iridocornealis– Contains and reabsorps humor aquosus
Iridocorneal angle= angulus iridocornealis
At the sclerocorneal junction
Trabecular frame of the back side = spatia anguli i.c. = Fontana spaces
Not connected with Schlemm canal
Resorption of humor aquosus
Maintenance of intraocular pressure
!!! No parasympaticolytics in glaucoma !!!
OCT
Optical coherent tomograp
h
measurement of light
reflection
Tunica interna (nervosa)= Retina
pars caeca – pars iridica– pars ciliaris
ora serratapars optica – 11 layers
– pigment part– Sensory part
Tunica interna (nervosa)Retina – pigment part
stratum pigmentosum Single layer cuboid epithelium cells (pigmentocytus) connected by tight junction Apical part contains melanin granules Surrounds external segments of sensory cells interfotoreceptor matrix
Cell nutrition, fotopigment rejuvenation, degradation of membranous discs
Tunica interna (nervosa) Retina – sensory part
Light recepting neurons– Rods and cones
Conduction neurons– Bipolar and ganglionic cells
Association neurons– Horizontal and amacrine cells
Supportive cells (glia)– Müllers cells
Tunica interna (nervosa) Retina – sensory part
discus n. optici (= blind spot) – No light perceiving elements
excavatio disci
macula lutea (= yellow spot) – higher layers to the side– Sharpest vision
– fovea centralis (100.000 cones) foveola (2500 cones)
Tunica sensoria (interna)Rods = Neuron bacilliferum rod = bacillum retinae synaptic disc (discus membranaceus) axon nucleus Inner segment
– GA, ER, MIT; synthesis of ATP and rhodopsin
Outer segment (segmentum externum)– Membranous discs with fotopigment
– migrate externally till separation
black-white vision
Tunica sensoria (interna)Cones = Neuron coniferum
rod = conus retinae synaptic pod (pes terminalis) fotopigment is iodopsin External segment
– Membranous discs with fotopigment• Communicate with around
Color vision – three types of rods – according to wave length– „blue“ – 420 nm – type S– „green“ – 535 nm – type M– „red“ – 565 nm – type L
Tunica sensoria (interna)conduction neurons
Bipolar cells (Neuron bipolare)– Staminate bipolare cells (n.b. bacillotopicum)
– Cony bipolar cells (n.b. conotopicum) • Dwarfy cells (n.b.c. nanum) x diffuse cells (n.b.c. diffusum)
– contact with ganglionic cells
Ganglionic cells (N. ganglionare multipolare)– Diffuse type (n.g.m. umbelliforme) – connects more bipolar cells
– Dwarfy type (n.g.m. nanum) – connects to dwarfy bipolar cell
– Their axons form nervus opticus
Tunica sensoria (interna)Association neurons
Have only axonal extensions – both directionHorizontal cells (N. horizontale)
– Connection with rods and cones
Amacrine cells (N. amacrinum)– Connection with bipolar and ganglionic cells
Modification and synchro of signal
Tunica sensoria (interna)supporting cells
Müllers cells (Gliocytus radialis)– macroglia– processus radiales– Have their own BL = membrana limitans
interna– zonulae adherentes with rods and cones
• = membrana limitans externa
Tunica sensoria (interna)Vrstvy zrakové části sítnice
celkem 11 vrstev
!!! neděste se !!!
Tunica sensoria (interna)layers of visual part of retina
stratum pigmentosum (1.) stratum nervosum (2.-10.)
– stratum segmentorum externorum et internorum(2.)– stratum limitans externum (3.)– stratum nucleare externum (4.)– stratum plexiforme externum (5.)– stratum nucleare internum (6.)– stratum plexiforme internum (7.)– stratum ganglionicum (8.)– stratum neurofibrarum (9.)– stratum limitans internum (10.)
Tunica sensoria (interna)Specific places of retina
ora serrata – termination of sensory epithelium pars optica – 10 layers
– discus n. optici /formerly papilla/ (= blind spot) – place of nerve separation
• No light detecting elements
• excavatio disci
– macula lutea (= yellow spot) – higher layers bent to the side, sharpest vision
• fovea centralis (100.000 cones) – only cones
– Higher layers bent side
– Sharpest vision
foveola (2500 cones)
OCT
Optical coherent
tomograph
measurement of light
reflextion
OCT
OCT
Retinal dystopia
Arterial supply of eye
a. carotis interna a. ophthalmica aa. ciliares posteriores breves choroidaa. ciliares posteriores longae (24) corpus
ciliare + irisaa. musculares aa. ciliares ant., aa.
episclerales, aa. conjuctivales lat.a. centralis retinae retinaa. lacrimalis aa. palpebrales lat.aa. palpebrales med. aa. conjuctivales med.
Vasa sanguinea retinae– eye backside (fundus oculi)
a. centralis retinae arterioles
a. temporalis sup.+ inf. a. nasalis sup.+ inf. a. macularis sup.+ inf.
(+ media)
Veins corresponding to arteries, often crossing
Arteria cilioretinalis
appearance: 10-33 % Branch from a. ciliaris posterior brevis Enters via discus n.II independently on a. centralis
retinae Acessory arterial supply of macula lutea from
choroid circuit Only source of blood for retina during closure of
a. centralis retinae 90 % temporally - 10 % nasally closure of a. cilioretinalis → central scotoma Closure of a. centralis retinae → spared central
vision of macula lutea
A. cilioretinalis
Venous supply of eye – 3 directions
vv. episcleralesvv. ciliares ant. vv. sclerales sinus venosus
sclerae Schlemmi s. Lauthivv. vorticosae (4 in quadrants of eye ball)v. centralis retinaev. ophthalmica sup. sinus cavernosusv. ophthalmica inf. plexus pterygoideusv. angularis v. facialis v. jugularis int.
! Danger of inflammation spreading !
Nervous supply of eye
n. opticus – sensory– pars intraocularis, canalis, intracranialis
– vagina interna, externa
n. ophthalmicus nn. ciliares longi – sensory n. lacrimalis, n. frontalis, n. nasociliaris – for surrounding nn. ciliares breves ganglion ciliare - autonomous
(sympaticus does not connect, parasympaticus yes)
n.III., n. IV., n.VI – motoric
Nervus opticus
Exvagination of diencephalon (thalamus opticus)
Axons separated by endoneuriumOn the surface are analogs of cerebral
coverings Inside nervus running a. et v. centralis
retinea
OPTICAL PATHProjection → Ascending → Sensory path
4 - neuronal, partially crossed
• neuron: rods and cones of retina• neuron: bipolar cells of retina• neuron: ganglionic cells of retina n. II chiasma
opticum corpus geniculatum laterale• neuron: cells of corpus geniculatum laterale
tractus geniculocorticalis (= radiatio optica Gratioleti) lobus occipitalis, area 17 (around fissura calcarina)
Visual pathsides from 3rd neuron
into hypothalamus (nucleus suprachiasmaticus) – transfers optical signals to highest vegetative centers (sight of food = salivation)
Tracts of pupillary reflex – via area pretectalis to nucleus accessorius dorsalis n. III /Edinger-Westphal/ - parasympatic
path vith n. III ganglion ciliare nn. ciliares breves m. ciliaris et m. sphincter pupillae /miosis + acommodation/
into retikular formation tractus reticulospinalis centrum ciliospinale /Budge/ C8-Th1 sympathetic path in truncus symphaticus ganglion cervicale superius plexus caroticus internus et ophtalmicus nn. ciliares breves m. dilatator pupillae /mydriasis/
Path for convergence nucleus interstitialis /Cajal/ fasciculus longitudinalis medialis nuclei of all eyeball moving nerves
Tectal visual circuit - tractus tectospinalis (direction of eyeball synchro, head and neck towards visual inputs and for coordination of whole body movements)
Acessory apparatus= Structurae oculi pertinentes
Fibrous apparatus = Apparatus ligamentosus
Lids = PalpebraeConjunctiva = ConjunctivaLacrimal apparatus = Apparatus lacrimalisMuscular apparatus = Apparatus musculariseyebrow = Supercilium
Fibrous apparatus
periorbitavagina bulbi (= capsula Tenoni)
– lig. suspensorium bulbi
spatium episcleralecorpus adiposum orbitae fasciae musculares
Conjunctiva = Tunica conjunctiva
t.c.bulbi et palpebrarum fornix superior, inferior Continuation of corneal epithelium, continues from
behind to eyelid, covers ventral side of eyeball Multi layer cylindrical epithelium Contains cup cells Lacrimal film (irroratio lacrimarum) glanduale conjuctivales Wolfringi caruncula lacrimalis
Lids = Palpebrae
palpebra superior, inferior tarsus superior (10 mm), inferior (5 mm) lig. palpebrale med. (2 lines) + lat. facies ant.+post., rima palpebrarum, commissura palp.
med.+lat., limbus ant.+ post. angulus oculi med.+ lat. m. tarsalis sup.(Mülleri) + inf. – smooth muscles pars palpebralis m. orbicularis oculi - n. VII m. levator palpebrae superioris - n. III eyelashes = cilia
Lids = Palpebrae External skin part
– Multi layered flat cuboid epithelium w exfoliation
– gll. sebaceae Zeissi • Ceruminous glands - hordeolum
– eyelashes + gl. ciliares Molli• Apocrine glands
m. orbicularis oculi Tarsal plate
– fibroelastic– gll. tarsales Meibomi
• Ceruminous glands - chalazion
Inner conjunctive part– Epithelial transition - sulcus
Lacrimal apparatus= Apparatus lacrimalis
glandula lacrimalis – pars orbitalis + palpebralis
– 12 – 15 individual ductuli excretorii
glandulae lacrimales accessoriae Krausei rivus lacrimalis lacus, papilla, caruncula lacrimalis puctum, canaliculus lacrimalis saccus lacrimalis ductus nasolacrimalis (plica
lacrimalis Hasneri) meatus nasi inf. In drainage lacrimal pathways more small villi
Glandula lacrimalis tubuloacinous serous glands with myoepitelial
cells
Svalové ústrojí
mm. recti bulbi: sup., inf., med., lat. (VI.)mm. obliqui bulbi: inf., sup.(IV.)
– /fovea trochlearis, spina trochlearis, trochlea, vagina m.o.b.s./
m. levator palpebrae sup. (pars spf.+prof.)n. III – ostatních 5 svalů
hladké svaly: m. orbitalis Mülleri, m. tarsalis sup. Mülleri + inf.
Movements of eyeball I.Movements of eyeball I.
Movements around axes = duction Around vertical axis
– adduction (inside)– abduction (outside)
Around horizontal axis– elevation (sursumduction; supraduction): up– depression (deorsumduction; infraduction): down
Around sagittal axis (ventrodorsal) :– intorsion (incykloduction): flapping inside– extorsion (excykloduction): flapping outside
Movements of eyeball II.Movements of eyeball II.Movements paired (together with both eyeballs)
Same directed conjugated paired movements = version (conjugated movements)– dextroversion (right) + sinistroversion (left)– supraversion (sursumverza) + infra/deorsumverza (up + down)– dextro/sinistroelevation + dextro/sinistrodepression (up/down and to sides)– dextro/sinistrocycloversion (rotation right/left)
Counter directed non conjugated paired movements = vergence (non conjugated movements)– convergence = inside direction of axes from both eyeballs– divergence = outside direction of axes from both eyeballs
strabismus = heterotropie = cross eye:– one eye is persistently rotated inward or outward
Eyeball movements
Strabismus concomitans
esotropie (s. convergens)
exotropie (s. divergens)
hypertropie (s. sursumvergens)
hypotropie (s. deosumvergens)
Development of visual apparatus
neuroectoderm of ventral forebrainSurface ectoderm of head In between mesenchymeCells of neural crest
Development of visual apparatus
Development since 4th weekOrigin of eye rims in ventral forebrainDeepens into eye sacsFormation of eye stalk Induction of ectoderm = thickeningOrigin of eye placode
Development of vision apparatus
Invagination of eye placodeOrigin of hollow lentiform sac w/o
connection with surfaceEye sacs invaginate = eye cup Invagination of stalk and cup with entering
of vascular mesenchyme = origin of vitreal vessels
Development of retina
Origin from eye cupExternal layer – pigment epithelium Inner layer – proliferates in pars nervosa Intraretinal space – gradually disappears
Inversion of retina
Development of nervus opticus
Fibers from ganglionic cells growth through stalk
lumen of stalk ceasesFissure (invagination) ceases
BRAIN
3 brain ‘vesicles’ are subdividing
Cephalic flexure/bend
35 days pcDEVELOPMENT of the EYE I from CNS
Telencephalon
Diencephalon
Mesencephalon
now four, then Rhombencephalon divides into Met- & Mel-encephalons
Cervical flexure
Rhombencephalon
start the folding
Already before 35d pc, on each side of the ‘head’, interactions have started between surface ECTODERM, a bulge of the FOREBRAIN & the MESENCHYME
Surface ECTODERM
MESENCHYME RETINA Neural ECTODERM
CORNEAL EPITHELIUM
EYE PARTS’ EMBRYONIC SOURCES
UVEA
LENS
Connective tissue & muscle (& vessels) come from cranial mesenchyme
Surface ECTODERM
MESENCHYME RETINA Neural ECTODERM
SCLERALENS
CORNEAL STROMA VITREOUS
RETINA
OPTIC NERVE
Two ectoderms drive events and shaping
CORNEAL EPITHELIUM
ANTERIOR EYE PARTS’ EMBRYONIC SOURCES
Surface ECTODERM
LENS
How does a surface layer produce two separate structures?
In much the same way as an endocrine gland is produced: by a downgrowth of cells that then break off the surface connection
Here the downgrowth makes the lens vesicle, conferring a roundish shape from early on
To have enough cells for the future cornea and for the lens vesicle, the surface ectoderm first thickens to form a lens placode
over the brain-derived optic vesicle
Mesenchyme
LENS & OPTIC CUP DEVELOPMENT I
While still growing, both placode and end of the optic vesicle invaginate
lens placode
optic vesicle
Double wall of optic cup is starting to form
Intraretinal space
Mesenchyme
Optic vesicle precedes the lens vesicle and is a distinct structure
OPTIC CUP DEVELOPMENT II: Choroid fissure
Together with the invagination centrally at the end of the optic cup,
MesenchymeBlood vessels have to be introduced early into the soon to be enclosed round eye
an invagination along the cup & stalk’s inferior surface occurs, to create the choroid fissure
in which runs the hyaloid artery
OPTIC CUP DEVELOPMENT II: Coloboma
Together with the invagination centrally at the end of the optic cup,
Blood vessels have to be introduced early into the soon to be enclosed round eye
an invagination along the cup & stalk’s inferior surface occurs, to create the choroid fissure
in which runs the hyaloid arteryAlso, an annular vessel
runs around the outside of the optic cup
Mesenchyme
Imagine a penis in which the urethra near & into the glans is still open on its underside - the condition of hypospadias - (but now contains an artery)
Defects in the eye from failure of the choroid fissure to close are colobomas
MesenchymeMesenchyme
OPTIC DEVELOPMENT III: Lens vesicle
Deeper part of Placode sinks into mesenchyme & makes a vesicle
Attachment to surface ectoderm will be broken
LENS VESICLE
Optic cup becomes deeper
Inner wall thickenslens placode
so that surface ectoderm can become corneal epithelium & intervening mesenchyme can form the corneal stroma
OPTIC DEVELOPMENT IV: Lens differentiation
Posterior vesicle cells become elongated lens cells
Attachment to surface ectoderm lostMesenchyme
Anterior vesicle cells become subcapsular epithelium
Mesenchyme
Basal lamina becomes lens capsule
Posterior vesicle cells form the nucleus of the lens. Subsequent lens cells derive from the subcapsular epithelium
OPTIC DEVELOPMENT IV: Lens differentiation
Posterior-vesicle cells elongate to lens cells
Anterior-vesicle cells become subcapsular epithelium
Mesenchyme
Basal lamina becomes lens capsule
Lumen obliterated
LENS
OPTIC DEVELOPMENT V: Retina differentiation I
Outer layer of cup stays thin and beomes pigment cell layer
Intra-retinal space occluded
Mesenchyme
Inner layer of cup thickens and becomes Neural layer
Hyaloid artery reaches inside cup
After a while, the lens and vitreous no longer need it, and it atrophies. Only the neural retina continues to depend on it, but under another name - central artery of the retina
OPTIC DEVELOPMENT VI: Retina differentiation II
MesenchymeInner layer of cup thickens and becomes Neural layer
Where cells multiply, form layers and differentiate to the several cell types of the neural retina
Outer layer of cup stays thin and beomes pigment cell layer
Development of ciliary body
Protrusion of both layers of eye cuppigment epithelium – from external layerNon pigmented epithelium – from inner
layerCilliary canal – from cavity of cupm. ciliaris and tissue – from mesenchyme
Iris development
Margin of eye cupExternal layer changes into smooth muscles Inner layer creates pigment epithelium
Lens development Originates from lentiform sac
– Anterior wall is not changing = anterior epithelium
– Posterior wall – cells elongating till lumen extinction
• Origin of primary fibers• Secondary fibers – from cells of
anterior epithelium
– capsula lentis – thickened basal lamina of anterior epithelium
Supplied by a. hyaloidea – ceases Pupillary membrane – covers lens
– ceases
Development of eye chambers
Anterior chamber – Rift between origin of lens and cornea
Posterior chamber– Rift inside eye cup alongside lens
Development of cornea, uvea and sclera
cornea– Surface mesoderm– mesenchyme– Cells of neural crest
Choroidea and sclera – Surrounding mesenchyme
Development of eye palpebras
6th week: skin folds over cornea 10th week: folds connectiong 28th week: again opening During that time from inside attaches conjunctiva
Muscle from IInd branchial arch Tarsal plate and glands from mesenchyme
Development of lacrimal glands
Invagination of surface ectoderm
Non functional till approx. 6th week after delivery– Newborn is not lacrimating
Developmental defects Inborn retinal dystopia coloboma retinae (usually bilateral – defect of fissura optica
closure) cyclopia (1 eye), synophthalmia (fused eyes) microphthalmia – infection anophthalmia coloboma iridis (6th week – defect of fissura optica closure aniridia, aphakia membrana pupillaris persistens a. hyloidea persistens Inborn green cataracta; inborn cataracta (in galactosemia) Inborn ptosis, coloboma palpebrale cryptophthalmia (eyelids missing – eye covered by skin)
Examination
Slit-lampExamination of the eye ground – oedema of
discus/papilla n. optici = increased intracranial pressure
perimetria = examination of the width of the eye field
optometria = examination of the quality of vision
OCT (optical coherence tomography)
Goldmann applanation tonometry
OCT
Slit lampOCT
Symptomes and malfunctions epiphora (excesive lacrimation) myopia – hypermetropie (short – long vision) hypermetria (overshooting – lesion of cerebellum!) presbyopia (elder eye) hemeralopia (anopsia in twilight) amblyopia (blunt-sighted) – functional lesion (ce when
strabismus) daltonismus (colorless vision)