June 12, 2013
New Layer To Human Cornea Discovered By Researchers
April Flowers for redOrbit.com - Your Universe Online
A previously undetected layer in the cornea, the clear window at the front of the human eye, has been discovered by scientists at The University of Nottingham. This new layer, called the Dua´s Layer after Professor Harminder Dua who discovered it, could help surgeons to dramatically improve outcomes for patients undergoing corneal grafts and transplants.
"This is a major discovery that will mean that ophthalmology textbooks will literally need to be re-written. Having identified this new and distinct layer deep in the tissue of the cornea, we can now exploit its presence to make operations much safer and simpler for patients,” said Dua, Professor of Ophthalmology and Visual Sciences.
"From a clinical perspective, there are many diseases that affect the back of the cornea which clinicians across the world are already beginning to relate to the presence, absence or tear in this layer."
The cornea is a clear protective lens on the front of the eye through which light enters the eye. Before this study, scientists believed the cornea to be comprised of five layers. These layers, from front to back are the corneal epithelium, Bowman's layer, the corneal stroma, Descemet's membrane and the corneal endothelium. The new layer, described in the journal Ophthalmology, is located at the back of the cornea between the corneal stroma and Descemet´s membrane. The whole cornea is approximately 550 microns, or 0.5 mm, thick, with the newly discovered layer making up about 15 microns. Despite its relative thinness, the Dua´s layer is incredibly tough and strong enough to be able to withstand one and a half to two bars of pressure.
To prove the existence of the layer, the researchers simulated human corneal transplants and grafts using eyes donated to eye banks for research purposes. They injected tiny bubbles into the cornea, gently separating the different layers. The separated layers were then subjected to electron microscopy, which allowed the scientists to study them at many thousand times their actual size.
By understanding the location and properties of the Dua´s layer, surgeons will be better able to identify where in the cornea these bubbles are occurring. The scientists being able to inject a bubble next to the Dua´s layer means that the layer´s strength will make it less prone to tearing. This means a better outcome for the patient.
This discovery will advance understanding for scientists and doctors about the number of diseases of the cornea, including acute hydrops, Descematocele and pre-Descemet's dystrophies.
The research team suggests that corneal hydrops, a bulging of the cornea caused by fluid build-up that occurs in patients with keratoconus (conical deformity of the cornea), is caused by a tear in the Dua layer, through which water from inside the eye rushes in and causes waterlogging.