The research has shed light on a characteristic of a thin membrane called the Descemet’s membrane
Professor Dua said, “This work has demonstrated a clear structural uniqueness of the pre-Descemet’s layer (Dua’s layer) and has also answered a puzzling surgical question on the reason why the Descemet’s membrane rolls in one direction when peeled off the donor’s eye. This understanding will pave the way to develop strategies to unroll it during transplantation, with minimal damage to the cells it supports.”
The Descemet membrane, named after the French doctor who discovered it in the late 18th century, is found between the pre-Descemet’s layer (Dua’s layer) and the endothelial layer in the back of the cornea, which is responsible for pumping out excess fluid and keeping the cornea dehydrated enough to maintain clear vision.
In some diseases such as Fuchs Dystrophy or following cataract surgery, the endothelial cells and Descemet membrane are damaged, causing the cornea to become waterlogged and the vision to become clouded. Over time, the vision deteriorates and, if left untreated, can lead to loss of sight.
To cure this problem, patients may be offered one of several types of corneal transplant in which all or different parts of the damaged cornea are removed and replaced with healthy tissue from a donor.
Ophthalmologists have long observed that the Descemet membrane will only roll in one direction, leaving the endothelial cells on the outside of the curl, but have been puzzled about why this occurs.
The Nottingham research has revealed for the first time that the direction of the roll is governed by the content and distribution of elastin – elastic-like fibres within the membrane.
Researchers found that the pre-Descemet layer had the highest elastin content of all the tissues studied but that the elastin was evenly distributed across the tissue.
However, when they came to study the Descemet membrane they found that the elastin was concentrated in a band across its front which was causing the membrane to roll up.
The study also found that the removal of the endothelial cells from the membrane made no difference to the direction of rolling proving that it was the elastin and not the cells that were responsible for the characteristic unidirectional rolling.
The results are significant as it shows that enzymes could potentially be used to weaken the rolling of the tissue, making it much easier for surgeons to successfully implant it into the cornea while reducing the potential damage to the endothelial cells which are so important in helping to regulate the fluid content of the cornea.
The full findings are present in the- American Journal of Ophthalmology.