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DEPARTMENT OF OPHTHALMOLOGY TVMC. EMBRYOLOGY AND CONGENITAL ANOMALIES OF LENS. EMBRYOLOGY. The eye lens develops from the SURFACE ECTODERM From neural tube arises the primary brain vesicles representing the prosencephalon , mesencephalon & rhombencephalon.

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embryology
EMBRYOLOGY
  • The eye lens develops from the SURFACE ECTODERM
  • From neural tube arises the primary brain vesicles representing the prosencephalon ,mesencephalon & rhombencephalon
slide4

3 rd week of IUL – Optic groove appears

  • 4th week of IUL – Optic vesicle develops & lens plate appears
slide5

Optic vesicle grows laterally & comes in contact with the surface ectoderm

  • Surface ectoderm overlying the optic vesicle thickens to form LENS PLACODE
slide6

Surface ectoderm sinks below & is converted into lens vesicle

  • The lens vesicle seperates from surface ectoderm at 33rd day of IUL
slide7

LENS PLACODE

  • LENS PIT
  • LENS VESICLE
formation of lens fibres
FORMATION OF LENS FIBRES
  • Primary lens fibres: Cells of the posterior wall

of lens vesicle elongate

  • Cavity of the lens vesicle is obliterated
  • This elongated posterior wall cells form the

primary lens fibres

  • Formation completes in 3rd month of IUL and this compact core of lens is called as EMBRYONIC NUCLEUS
secondary lens fibres
Secondary lens fibres
  • Now the cells of the anterior epithelium which are active throught life divide continuously .
  • This forms the SECONDARY LENS FIBRES which give a lamellated appearance on cross section as the cells are laic concentrically
  • Depending on the age of fibres , the secondary lens fibres are called as:
  • FETAL NUCLEUS – 3rd to 8th month
  • INFANTILE NUCLEUS- till puberty
  • ADULT NUCLEUS- after puberty
congenital anomalies of the lens
CONGENITAL ANOMALIES OF THE LENS
  • Coloboma of the lens
  • Congenital ectopialentis
  • Congenital cataract
  • Lenticonus
  • Microspherophakia
coloboma of lens
COLOBOMA OF LENS
  • Defective development of part of suspensory ligament
  • Notch shaped defect in the lens, usually the inferior margin
congenital cataract
CONGENITAL CATARACT
  • Opacity of lens since birth
  • Occurs due to disturbance of lens fibre formation
  • It is limited to the embryonic or foetal nucleus
  • Persistance of hyaloid arterial system also leads to cataract
causes of congenital cataract
CAUSES OF CONGENITAL CATARACT
  • Hereditary 1/3 , dominant inheritance
  • Infections- rubella , toxoplasma, CMV
  • Malnutrition
  • Drugs- corticosteroids ,thalidomide
  • Radiation exposure
  • Foetal anoxia, galactosemia, myotoniadystrophica, lowe’s syndrome, congenital icthyosis
ectopia lentis
ECTOPIA LENTIS
  • Congenital dislocation or subluxation of the lens
  • SUBLUXATION- partial dislocation of lens
  • DISLOCATION – complete displacement of lens.
  • Causes: marfan’s syndrome, ehler’sdanlos syndrome, homocysteinuria, weilmarchesani syndrome
lenticonus
LENTICONUS
  • Abnormal curvature of the lens leading to a conical surface
  • More common posteriorly than anterior surface of the lens
  • Posterior lenticonus is seen in alport’s syndrome
microspherophakia
MICROSPHEROPHAKIA
  • Frequently associated with weilmarchesani syndrome
  • In this condition the lens is spherical in shape & small in size
  • Spherophakia- spherical lens
  • Microphakia- small lens.
slide22

THANK YOU

Presented by VaniNarayani.K , 3rd yr MBBS