New layer in human eye discovered

Scientists have discovered a previously unknown layer lurking in the human eye.

The newfound body part, dubbed Dua's layer, is a skinny but tough structure measuring just 15 microns thick, where one micron is one-millionth of a meter and more than 25,000 microns equal an inch. It sits at the back of the cornea, the sensitive, transparent tissue at the very front of the human eye that helps to focus incoming light, researchers say.

The feature is named for its discoverer, Harminder Dua, a professor of ophthalmology and visual sciences at the University of Nottingham. Dua said in a statement that the finding will not only change what ophthalmologists know about human eye anatomy, but it will also make operations safer and simpler for patients with an injury in this layer.

"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," Dua said in a statement.

Dua and colleagues, for example, believe that a tear in the Dua layer is what causes corneal hydrops, which occurs when water from inside the eye rushes in and leads to a fluid buildup in the cornea. This phenomenon is seen in patients with keratoconus, a degenerative eye disorder that causes the cornea to take on a cone shape.

Dua's layer adds to the five previously known layers of the cornea: the corneal epithelium at the very front, followed by Bowman's layer, the corneal stroma, Descemet's membrane and the corneal endothelium at the very back.

Dua and colleagues found the new layer between the corneal stroma and Descemet's membrane through corneal transplants and grafts on eyes donated for research. They injected tiny air bubbles to separate the different layers of the cornea and scanned each using an electron microscope.

The research was detailed in the journal Ophthalmology.