A new layer in the human cornea — discovered by researchers at The University of Nottingham last year — plays a vital role in the structure of the tissue that controls the flow of fluid from the eye, research has shown.
The findings, published in a paper in the British Journal of Ophthalmology, could shed new light on glaucoma, a devastating disease caused by defective drainage of fluid from the eye and the world’s second leading cause of blindness.
The latest research shows that the new layer, dubbed Dua’s Layer after the academic Professor Harminder Dua who discovered it, makes an important contribution to the sieve-like meshwork, the trabecular meshwork (TM), in the periphery of the cornea.
The
TM is a wedge-shaped band of tissue that extends along the circumference of the
angle of the anterior chamber of the eye. It is made of beams of collagen
wrapped in a basement membrane to which trabecular cells and endothelial cells
attach. The beams branch out randomly to form a ‘meshwork’.
Optic nerve damage
Pressure
within the eye is maintained by the balance of aqueous fluid production by eye
tissue called the ciliary body and drainage principally through the TM to the
canal of Schlemm, a circular channel in the angle of the eye.
Defective
drainage through the TM is an important cause of glaucoma, a condition that
leads to raised pressure in the eye that can permanently affect sight. Around 1
to 2% of the world’s population yearly have chronic glaucoma and globally
around 45 million people have open angle glaucoma which can permanently damage
the optic nerve — 10% of whom are blind.
The
latest research by Professor Dua and colleagues in Academic Ophthalmology at
The University of Nottingham sheds new light on the basic anatomy of Dua’s
Layer, which is just 15 microns thick but incredibly tough. Comprised of thin
plates of collagen, it sits at the back of the cornea between the corneal
stroma and Descemet’s membrane.
By
examining human donor eyes using electron microscopy, the researchers were able
to look at Dua’s Layer beyond the central part of the cornea to shed more light
on its features at the extreme periphery of the cornea. They discovered that
the collagen fibres of Dua’s Layer also branch out to form a meshwork and that
the core of TM is in fact an extension of Dua’s Layer.
Significant findings
It
is hoped the discovery will offer new clues on why the drainage system malfunctions
in the eyes of some people, leading to high pressure.
Professor
Dua said: “Many surgeons who perform lamellar corneal transplant recognise this
layer as an important part of the surgical anatomy of the cornea. This new
finding resulting from a study of the microanatomy of the periphery of the
layer could have significance beyond corneal surgery.”
The
breakthrough discovery of Dua’s Layer was first revealed in a paper in the
academic journal Ophthalmology in
June last year and was widely covered by the world’s scientific and lay media.
The
paper became the number one downloaded ophthalmology paper from the website
ScienceDirect between July and September 2013 and was ranked the 11th
most downloaded from the website for the whole of medicine and dentistry.
The
latest research paper, The Collagen
Matrix of the Human Trabecular Meshwork is an Extension of the Novel
Pre-Descemet’s layer (Dua’s layer), can be viewed online (after the embargo
lifts) at http://dx.doi.org/10.1136/bjophthalmol-2013-304593
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