|
Gestational Age
|
Crown Rump
(mm)
|
Lens Events
|
Associated Ocular
Events
|
|
Early 4th wk
|
4
|
Development of lens placode
|
Invagination of optic vesicle
to form optic cup
|
| |
5
|
Lens pit forms
|
Fetal fissure invaginating inferiorly
|
|
Late 4th wk
|
6
|
Lens vesicle completed
|
Hyaloid artery into fetal fissure
Annular vessel appears anterior
to optic cup
|
Late 4th and early 5th wk
Fetal fissure closure begins
|
7-9
|
Separation of lens vesicle
|
Optic cup invagination complete
Hyaloid system and tunica vasculosa
lentis forming
|
|
End of 5th wk
|
13
|
Lens capsule seen
|
Nerve fibers reach optic stalk
|
|
End of 6th wk
|
18
|
Primary lens fibers complete
|
Fetal fissure closed
Lid folds arising
|
|
8th week
|
26
|
Secondary lens fibers begin
|
Slit-like anterior chamber present
|
|
End of 8th wk
|
30
|
Y sutures forming
|
Cornea, anterior chamber well formed
|
|
3rd month
|
31-70
|
Fetal period begins
|
Optic cup grows forward
Major iris circle and pupillary
membrane form
Secondary vitreous secretion begins
|
|
End of 3rd month
|
65-70
|
Zonular fibers visible
|
Ciliary processes developing
|
|
4th to 5th month
|
71-150
|
Full zonular system
|
Tunica vasculosa lentis atrophies
|
|
8th month
|
|
Hyaloid artery tail in Cloquet's canal
|
Hyaloid artery detaches from disc
Pupillary membrane atrophied
|
|
Birth
|
|
Fetal nucleus close to
anterior capsule
|
|