1. DEPARTMENT OF OPHTHALMOLOGY TVMC

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  4 th 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 33 rd day of IUL

7.  LENS PLACODE  LENS PIT  LENS VESICLE

9. 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 3 rd month of IUL and this compact core of lens is called as EMBRYONIC NUCLEUS

11. 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: o FETAL NUCLEUS – 3 rd to 8 th month o INFANTILE NUCLEUS- till puberty o ADULT NUCLEUS- after puberty

14. CONGENITAL ANOMALIES OF THE LENS  Coloboma of the lens  Congenital ectopia lentis  Congenital cataract  Lenticonus  Microspherophakia

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

16. 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

17. CAUSES OF CONGENITAL CATARACT  Hereditary 1/3, dominant inheritance  Infections- rubella, toxoplasma, CMV  Malnutrition  Drugs- corticosteroids,thalidomide  Radiation exposure  Foetal anoxia, galactosemia, myotonia dystrophica, lowe’s syndrome, congenital icthyosis

18. CONGENITAL CATARACT

19. ECTOPIA LENTIS  Congenital dislocation or subluxation of the lens  SUBLUXATION- partial dislocation of lens  DISLOCATION – complete displacement of lens.  Causes: marfan’s syndrome, ehler’s danlos syndrome, homocysteinuria, weil marchesani syndrome

20. 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

21. MICROSPHEROPHAKIA  Frequently associated with weil marchesani syndrome  In this condition the lens is spherical in shape & small in size  Spherophakia- spherical lens  Microphakia- small lens.

22. THANK YOU Presented by Vani Narayani.K, 3 rd yr MBBS