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DEPARTMENT OF OPHTHALMOLOGY TVMC

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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DEPARTMENT OF OPHTHALMOLOGY TVMC

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  1. DEPARTMENT OF OPHTHALMOLOGYTVMC

  2. EMBRYOLOGY AND CONGENITAL ANOMALIES OF LENS

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

  4. 3 rd week of IUL – Optic groove appears • 4th week of IUL – Optic vesicle develops & lens plate appears

  5. Optic vesicle grows laterally & comes in contact with the surface ectoderm • Surface ectoderm overlying the optic vesicle thickens to form LENS PLACODE

  6. Surface ectoderm sinks below & is converted into lens vesicle • The lens vesicle seperates from surface ectoderm at 33rd day of IUL

  7. LENS PLACODE • LENS PIT • LENS VESICLE

  8. 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

  9. 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

  10. CONGENITAL ANOMALIES OF THE LENS • Coloboma of the lens • Congenital ectopialentis • Congenital cataract • Lenticonus • Microspherophakia

  11. COLOBOMA OF LENS • Defective development of part of suspensory ligament • Notch shaped defect in the lens, usually the inferior margin

  12. 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

  13. 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

  14. CONGENITAL CATARACT

  15. 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

  16. 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

  17. MICROSPHEROPHAKIA • Frequently associated with weilmarchesani syndrome • In this condition the lens is spherical in shape & small in size • Spherophakia- spherical lens • Microphakia- small lens.

  18. THANK YOU Presented by VaniNarayani.K , 3rd yr MBBS

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