The Eyes Have It

As a biomedical engineering student, we covered a lot of anatomy and physiology back in school, including a class on dental implants and a pig dissection. None of those things ever grossed me out or made me uncomfortable. The only chapter that ever made me cringe (and fortunately we didn't go into too much detail about it) was eyes. Something about the eyeball just creeps me out, and as someone who wears contacts and has extra-sensitive eyes, I am frequently at the eye doctors and considering Lasik (even though the idea of it makes me nauseous).

The eye is a pretty amazing and complex organ. They heal quickly and with proper care most corneal scratches repair in 48 hours or less. Humans blink about 12 times a minute, with the average blink lasting 1/20 of a second. And seeing is such an important part of everyday life that it requires about half the brain to get involved.

The reason I bring this all up is because scientists at the University of Nottingham have recently discovered an undetected layer in the cornea which could help surgeons dramatically improve the outcomes for patients undergoing corneal grafts and transplants. The cornea is the clean 'window' at the front of the eye that allows light to enter the eye. It is about 500 microns thick, incredibly tough, and strong enough to withstand one and a half to two bars of pressure. The cornea was originally thought to only have five layers. This new layer, named Dua's Layer (after the scientist who discovered it), is 15 microns thick and sits at the back of the cornea.

The discovery was made by Professor Harminder Dua and his colleagues by injecting air into the corneas of eyes that had been donated for research and using an electron microscope to scan each separate layer.

Dua notes, "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."

Did you know that Newborns don't produce tears. They make crying sounds, but the tears don't start flowing until they are about 4-13 weeks old." ^{Image Credit: myrna.info.}

Not only will the discovery mean that anatomy text books will have to be rewritten, but it means that now doctors can provide better outcomes for patients undergoing eye surgery and those with a disease of the cornea. One disease in particular, acute Hydrops, is a bulging of the cornea caused by fluid buildup and occurs in patients in a conical deformity of the cornea, which is caused by a tear in the Dua layer. This causes water from the inside of the eye to rush in and results in water logging.