This is the second lecture
dealing with lens development
and lens development disorders.
My name is Professor Chris Lloyd.
I'm a consultant
ophthalmologist at Great
Ormond Street Hospital in London.
I'm also an honorary consultant
at Manchester Royal Eye hospital
and honorary professor of
at Manchester Academic
Health Sciences Center
in the University of Manchester.
Congenital aphakia is an extremely
rare malformation of the eye.
It's usually associated with
other ocular malformations.
It can be caused by
rubella syndrome or
other early teratogenic
influences during the first four
weeks of gestation.
It can be caused by homozygous
mutations in the FOXE3 gene,
as illustrated by the
graphic to the right.
This is a case that was published
in Molecular Vision six years ago.
It can also occur as a
secondary phenomenon due
to persistent fetal vasculature.
a clinical description
of a spherical lens, a lens that is
reduced in its natural dimensions.
This can be caused by
These include mutations in the LTB2
gene, Weill-Marchesani syndrome,
homocystinuria, and other
like Aniridia or
which cause damage to the zonule.
Lens duplication is
also extremely rare.
It's associated with
uveal coloboma, and cornea plana,
or flattening of the cornea.
It's presumed to be due to
abnormal lens placode formation.
The case illustrating this
is published in the Indian
Journal of Ophthalmology.
Lens coloboma is due to a
failure of zonular development.
And the absence of zonules
in a sector of the lens
leads to a scalloped defect,
as illustrated in the graphics
to the right-hand side.
It can be isolated or part of the
uveo-retinal coloboma phenotype.
Very rarely, it can occur as
a secondary phenomenon due
to ciliary body medulloepithelioma.
Lenticonus and lentiglobus
of a developmental malformation
of either the anterior
or posterior lens surface.
Lenticonus means a
conical shape to the lens.
Lentiglobus means a spherical shape.
These two conditions
overlap and are clinically
difficult to differentiate.
is much more common.
It usually occurs axially, i.e.
Involving the central
part of the lens.
And it induces a myopic or
astigmatic refractive error.
is mostly unilateral.
It's not usually associated with
systemic or other ocular anomalies.
The unilateral type is
typically not genetic.
But bilateral lentiglobus
is usually genetic,
and it can be inherited in
either an X-linked or autosomal
Associations have been described
with microcornea, Duanes
syndrome, and anterior lenticonus.
Cataract occurs as a
due to lens fibre damage.
Posterior lenticonus is similar to
lentiglobus in that most cases are
usually unilateral and non-genetic.
It can occur in the presence of a
persistent hyaloid artery remnant.
And again, cataract occurs because
of damage to the lens fibres,
which lie adjacent to
the abnormal capsule.
This is presumed to be due to
osmotic changes in those lens
commonly genetic, again,
are the X-linked or
And associations have been
described with Trisomy 21,
Pai syndrome, and Pierson syndrome.
Anterior lenticonus is a description
of a thin central anterior capsule.
And the graphic on the right, which
is kindly given to me by Professor
David Taylor, illustrates that.
occurs in Alport syndrome.
And 25% of individuals
with Alport syndrome
have this lens abnormality.
Alport syndrome is mostly
X-linked, around 85%.
But it can be autosomal
recessive or autosomal dominant.
And it's caused by mutations
in the COL4A1 to COL4A6 genes.
These code for type IV collagen.
This leads to a basement
And as a result, individuals
with this condition
have renal problems leading to renal
failure, sensory neural deafness,
and other ocular anomalies,
in the retinal pigment epithelium.
Males with X-linked COL4A5
are severely affected.
Female carriers with this
are only mildly affected.