British ophthalmologists have discovered a new layer in the cornea, the clear, dome-shaped surface that covers the front of the eye.

The layer has been named the Dua’s Layer after the academic Prof Harminder Dua who discovered it.

“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 Dr Harminder Dua, Professor of Ophthalmology and Visual Sciences at the University of Nottingham and lead author of a paper published in the journal Ophthalmology.

“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 human cornea is the clear protective lens on the front of the eye through which light enters the eye. Scientists previously believed the cornea to be comprised of five layers, from front to back, the corneal epithelium, Bowman’s layer, the corneal stroma, Descemet’s membrane and the corneal endothelium.

The Dua’s Layer is located at the back of the cornea between the corneal stroma and Descemet’s membrane.

Although the layer is just 15 microns thick — the entire cornea is around 550 microns thick or 0.5mm — it is incredibly tough and is strong enough to be able to withstand one and a half to two bars of pressure.

The scientists now believe 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’s layer, through which water from inside the eye rushes in and causes waterlogging.

The discovery will have an impact on advancing understanding of a number of diseases of the cornea, including acute hydrops, Descematocele and pre-Descemet’s dystrophies.

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Bibliographic information: Harminder S. Dua et al. 2013. Human Corneal Anatomy Redefined: A Novel Pre-Descemet’s Layer (Dua’s Layer). Ophthalmology, in press; doi: 10.1016/j.ophtha.2013.01.018