Keratoconus and New Stem Cell Research

The Hargrave Eye Center’s latest post:

Did you know the cornea is the only living tissue that has no direct or indirect connection to blood vessels to obtain the oxygen and nutrients it needs to remain healthy? Instead, it absorbs oxygen from the outside air (diffused through the tears) and it gains nutrients from the inside using the aqueous humor (fluid that fills the chamber behind it).

According to WebMD, we see through the cornea, which can be described as the clear outer lens or “windshield” of the eye. Normally, the cornea has a dome shape, like a ball. Sometimes, however, the structure of the cornea is just not strong enough to hold this round shape and the cornea bulges outward like a cone. This condition is called keratoconus.

Keratoconus is a progressive non-inflammatory disorder that causes a characteristic thinning and cone-like steepening of the cornea. According to WebMD, it is caused by a decrease in protective antioxidants in the cornea. The cornea cells produce damaging by-products, like exhaust from a car. Normally, antioxidants get rid of them and protect the collagen fibers. If antioxidants levels are low, the collagen weakens and the cornea bulges out.

How is Keratoconus treated?

Treatment usually starts with new eyeglasses. If eyeglasses don’t provide adequate vision, then contact lenses, usually rigid gas permeable contact lenses, may be recommended. With mild cases, new eyeglasses can usually make vision clear again. Eventually, though, it will probably be necessary to use contact lenses or seek other treatments to strengthen the cornea and improve vision.

However, most recently, researchers in Japan and Wales found that human cells reprogrammed to become stem cells were able to form cornea tissue in lab dishes. This was reported on March 9th in the Science and Medicine publication, Nature. The stem cell tissue was used to repair the damaged outer layer of the cornea in rabbits. In a separate study also published March 9 in Nature, researchers in China and the United States coaxed stem cells in the eyes of a dozen babies born with cataracts to regrow clear lenses.

The researchers also studied 37 babies who were born with cataracts. Regular cataract surgery, which involves removing the cloudy lens and replacing it with a plastic one, was done for 25 of the babies. In the remaining 12 babies, doctors made a small incision in the side of the sack containing the lens and extracted the cataract, but didn’t replace the lens. Stem cells in the sack generated a new lens within about three months of surgery.

While both studies are technically proficient and provide new approaches to treating cataracts or corneal injuries, neither will soon be ready for widespread use in the clinic, says Henry Klassen, an ophthalmologist at the University of California, Irvine School of Medicine.

Sources:

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from Hargrave Eye Center | Corneal Transplantation http://ift.tt/1nSr04c

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