medical students and residents

1. RETINA EMBRYOLOGY
PRESENTER; Dr. Joshua Youze - Mmed 1
MUHAS - Ophthalmology Resident

2. INTRO…
• The retina innermost and light sensitive
of the three tunics of the eye,
surrounding the vitreous body and
continuous posteriorly with the optic
nerve.
– It consists of 10 layers.

4. Embryology
• The embryology of the human eye is 1st seen
in the 22nd day of the intra uteral life, as
bilateral evagination of the neuroectoderm of
the forehead.
– To be precise the diencephalon.

6. • The bilateral envagination of the diencephalon
give rise to the optic groove or optic sulci.
• The groove keeps on growing to form the
optic vesicles, which grows towards the
ectoderm.

8. • At 29th day the optic vesicles, moves laterally
towards the ectoderm. As they grow towards
the ectoderm from the forebrain, they
become attenuated to form optic stalk which
will later become optic nerve.
• When they reach the ectoderm the induction
of the formation of the lens primodia is
induced

10. • At 33 day the optic disc start to invaginate,
forming optic cup. The ends of the optic disc
remains not fused to create choroidal fissure.
• The choroidal fissure transmit the Hyaloid
artery and vein which later will become the
central retina artery and Vein after the closure
of the fissure.

13. • The choroidal fissure will later on fuse
completely and enclose the hyaloid artery and
vein in the canal within the optic stalk.
• When the lens is fully formed in intrauterine
the distal hyaloid artery will disintegrate and
the proximal part will remain to form the
central retina artery.

15. • The ectoderm which is anterior to the
invagination enlarge and detach into the
interior part of the optic cup to form the
primary lens which will be floating on one end
of the optic cup.
• The space between the lens and the cup is
filled by the mesenchyme tissue which is the
primary vitreous body.
LENS.

18. • The hollow ball become indented and the 2
layers of the cup formed(external and internal
retinal layers) separated by the intraretinal
space which is continuous with the optic stalk
and 3rd ventricle.
• The two layers are of different size as the
outer being thinner than the inner.

20. • The outer layer become pigmented layer and
the inner layer become neural layer
• The two layers are separated by the
intraretinal space.
• The optic cup is the divided into the anterior
1/5 and 4/5 posterior.

22. The anterior and posterior retina

23. • The anterior 1/5 will later differentiate to the
ciliary body and the iris.
• The cells immediately to the intraretinal layer
will begin differentiate to the photoreceptors.
• The next cells to muller supporting cells and
the bipolar neurons, and the innermost
superficial to become the axons of the
ganglion which will become optic nerve.

25. • At 8 months all layers of the retina are seen
histologically, but maturation of the
photoreceptors continues after birth.
– It explains why visual acuity of the baby improves
as the child grows.

26. Summary
• Evagination
• Formation of the optic vesicles
• Vesicles moves towards the ectoderm
• Formation of the lens primodia
• Invagination and formation of the optic cup.
• Differentiation of the optic cup layers to form
the retina