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Anatomi dan Embriologi Mata
Julie D Barliana
Divisi Pediatri OftalmologiDepartemen IK Mata FKUI/RSCM
Anatomi Bola MataKornea
Iris
Badan siliar
Lensa
Retina
Koroid
N Optikus (NII)
Badan kaca (vitreus body)
Anatomi Bola Mata
Badan Kaca (vitreus body)
Anterior chamber (Camera Oculi Anterior)
Posterior Chamber (Camera Oculi Posterior)
Central Vessel Retina
Hyaloid Canal)
Development of the Eye
I. First noticeable ~ 22days optic grooves—developing neural tube
Development of the Eye
II. As neural folds fuse (= forebrain formation) optic vesicles—evaginations of forebrain
Development of the EyeIIIa. Induction of lens placode (surface ectoderm)IIIb. Formation of optic stalk and optic cup from optic vesicle
Continued development ofoptic cup and lens
Optic cup —invagination of distaloptic vesicle to form doublewalled“cup”
Optic (choroid) fissure —sulcus onventral aspect optic cup/stalk(allows passage of vasculatureto lens & layers of cup)
Lens placode —ectodermalThickening
Lens pit—invaginates to formlens vesicle
Development of the retinaouter & inner portions of the optic cupClosure of choroid fissure ~ 6-7 weeks
Optic Cup
Inner layer —neuroepithelium“neural retina”
Outer layer—retinal pigmentepithelium
Intraretinal space
Cavity of optic stalk “filled”with axons of optic nerve
“Fusion” of inner and outerportions of the optic cup
Lens Development
lens placode in surface ectoderminvaginates as lens vesiclesupplied by hyaloid artery
Aphakia —absence of the lens (extremely rare) Moore and Persaud, 1998
Congenital cataracts—(e.g., rubella virus)Congenital galactosemia—cataract formation within 2-3 weeksof birth (galactose accumulation)
• Development of Ciliary Body and Irisboth develop from anterior portions of the optic cup and surrounding mesenchyme
• Ciliary muscle —smooth muscle derived from mesenchyme near the margin of the optic cup —”effects” accommodation reflex
• Iridial muscles —dilator and sphincter pupillae mm. Smooth muscles derived from neuroectoderm of the optic cup —control size of pupillary aperture
Iris dan Badan Siliar
Some Ocular Anomalies
Retinal detachment—between inner and outer portions of the optic cup derivatives
•congenital—failure of fusion •acquired—trauma
Defects in closure of optic (choroid) fissure •retinal coloboma•iridial coloboma
Aniridia — (rare) 1 in 75,000
Extraocular Muscles
Develop from somitomeres I-IV (paraxial mesoderm cranial to the occipital somites)
Innervated via CN III, IV, & VI
Coordinate movements between the two eyes(usually conjugate, although some instancesof physiological vergence exist)
Extraocular mm.Inferior oblique
Medial rectus
Superior oblique
Superior rectus
Levator palpebrae sup.
Lateral rectus
Inferior rectus(not shown)
Oculomotor Nerve (CN III)Somatic motor(oculomotor nucleus):Sup. rectus, Inf. rectus,Med. rectus, Inferior oblique& Levator palpebrae superiormm.
Parasympathetic(Edinger-Westphal nucleus):Ciliary m. &Constrictor pupillae m.
Trochlear Nerve (CN IV)Somatic motor only(trochlear nucleus):•Superior oblique m.
Abducens Nerve (CN VI)Somatic motor only(abducens nucleus):•Lateral rectus m.
Extraocular Muscle Anomalies (congenital)
• Agenesis (single muscle usually)• Anomalous Attachments
– misplaced– additional attachments
• Adherence & Fibrosis Syndromes
**Failure to align visual axes (strabismus), thus potentially resulting in diplopia (double-vision)
Amblyopia—reduced/absent visual ability in one eye “lazy” eye
VISUAL REFLEXES
Pupillary Light Reflexes: 30wks gestation– Constriction (parasympathetic)– Dilation (sympathetic)
Accommodation (4 months = well developed)(The Near Reflex)
Visual Developmental “Milestones”
• Pupillary Light Reaction—30 wks gestation(CN II/symp/parasymp integration)
• Lid closure in response to bright light—30 wks gest.(CN II—CN VII reflex)
• Blink response to visual threat—2-5months(CN II—CN VII reflex)
• Visual Fixation—birth (well dev=6-9wks)• Visual Following—3 months• Accommodation—4 months
Resources
• The Developing Human—6th Edition K. L. Moore & T. V. N. Persaud – 1998
• The Essentials—Walsh & Hoyt’s ClinicalNeuro-Ophthalmology—5th EditionEditors—N.R. Miller and N.J. Newman—1999
• Neuro-ophthalmology—3rd EditionEditor—J.S. Glaser—1999
Growth and Developmental of the Eye
Dimensions of the Eye
• Most of growth of the eye takes place in the first year of life
• The axial length occurs in 3 phases– Phase I: rapid period of growth (6 mos)-AL
increases 4 mm– Phase II and III: (age 2-5 years) and (age 5-13
years) growth slows-about 1 mm
Keratometry
• Cornea grows rapidly over the first several months of life (6 mos)
• Keratometry values change ,markedly in the first year of life:– 52 D at birth– Flattening to 46 D by 6 months– Reaching adult power of 42-44D by age 12
Corneal horizontal diameter
– 9.5-10.5 mm at newborns– 12 mm in adulthood
Most of changes occurs in the first year of life
Lens Power
• The power of the infant lens decreases dramatically over the first several years of life, an important fact to consider when implanting intraocular lenses (IOLs) in children undergoing cataract extraction in infancy and early childhood
Refractive Errors
The refractive state of the eye changes as – The AL increases– The cornea and lens flatten
• In general:– Infants are hyperopic at birth, – become slightly more hyperopic until age 7, and – a myopic shift until the eye reaches its adult size,
usually by about age 16
Visual acuity and Stereoacuity• Two major methods are used to determine VA in
preverbal infants and toddlers:– Visual evoked potentials (VEP) – Preferential looking (PL)
• VEP shows improvement of vision from about – 20/400 in infancy – 20/20 by age 6-7 mos
• PL studies estimate the vision of – a newborn infant 20/600, – 20/120 by 3 mos and – 20/60 by 6 mos.– 20/20 at 3-5 years