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