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

3 rd week of IUL – Optic groove appears

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

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

Surface ectoderm overlying the optic vesicle thickens to form LENS PLACODE

Surface ectoderm sinks below & is converted into lens vesicle

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

LENS PLACODE

LENS PIT

LENS VESICLE

FORMATION OF LENS FIBRES

Primary lens fibres: Cells of the posterior wall of lens vesicle elongateCavity of the lens vesicle is obliteratedThis elongated posterior wall cells form the primary lens fibresFormation completes in 3rd month of IUL and

this compact core of lens is called as EMBRYONIC NUCLEUS

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 – 3rd to 8th montho INFANTILE NUCLEUS- till pubertyo ADULT NUCLEUS- after puberty

CONGENITAL ANOMALIES OF THE LENS

Coloboma of the lensCongenital ectopia lentisCongenital cataractLenticonusMicrospherophakia

COLOBOMA OF LENS

Defective development of part of suspensory ligament

Notch shaped defect in the lens, usually the inferior margin

CONGENITAL CATARACT

Opacity of lens since birthOccurs 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

Hereditary 1/3 , dominant inheritanceInfections- rubella , toxoplasma, CMVMalnutrition Drugs- corticosteroids ,thalidomideRadiation exposureFoetal anoxia, galactosemia, myotonia

dystrophica, lowe’s syndrome, congenital icthyosis

CONGENITAL CATARACT

ECTOPIA LENTISCongenital dislocation or

subluxation of the lensSUBLUXATION- partial

dislocation of lensDISLOCATION – complete

displacement of lens.Causes: marfan’s

syndrome, ehler’s danlos syndrome, homocysteinuria, weil marchesani syndrome

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

Frequently associated with weil marchesani syndrome

In this condition the lens is spherical in shape & small in size

Spherophakia- spherical lensMicrophakia- small lens.

THANK YOU

Presented by

Vani Narayani.K , 3rd yr MBBS