Experiment By Chennai Scientists Raises Hope Of Curing Blindness Considered Irreversible

There is new hope for millions of people suffering from "irreversible" blindness due to retinal degeneration or damage. Scientists at Chennai–based Sankara Nethralaya say retinal cells grown from the remains of eyes donated for corneal transplant can be used to correct blindness and retina degeneration.

The scientists said they drew pigment cells from the iris (circular structure in the eye) and ciliary (circumferential tissue) from the donated eyes after the cornea was removed. When these cells were cultured in a petri dish and mixed with growth factors, it produced more cells. Genetic tests showed that these cells resembled and had characters of retinal cells. The study, accepted for publication in the journal Stem Cell Review and Reports, is funded by the department of bio–technology of the Union ministry of science and technology. "This experiment takes us closer to the hope that these cells may be able to cure blindness," said S Krishnakumar, head of Vision Research Foundation at Sankara Nethralaya.

A significant number of the 12 million blind in India suffer from preventable or reversible blindness, but doctors say the prevalence of retinal ailments such as diabetic retinopathy, degeneration and detachment is gradually increasing. Some of these diseases don’t have a cure and leave the affected people with permanent blindness. Across the world, scientists have been pinning their hopes on stem cells for treating retinal diseases. In April 2011, Nature published a report on how retina of rats could be created in a Petri dish from its own stem cells. In January 2012, Lancet reported that scientists used embryonic stem cells to improve the sight of two almost–blind women, a breakthrough that they say raises the hope of a cure for age–related vision loss.

The retinal cells will now have to be tested on animals before they can be adapted to humans. This may take years but it could offer an unlimited well of tissue to replace damaged retinas, said Srilatha Jasty, first author of the study. "If this is proven safe and effective in humans, an equal number of people are likely to be benefitted," she said.

Ophthalmologists say this success gives them hope that stem cells can help them grow organs. "Science can throw surprises. We may soon be able to grow organs in petri dishes, though it is still a long way," said Dr Amar Agarwal, ophthalmic surgeon of Agarwal Eye Hospital.

WHAT IS RETINA?
It is a light–sensitive tissue at the back of the inner eye. The retina converts light rays into electrical impulses that are sent

to parts of the brain concerned with sight through the optic nerve.

WHAT CAN THESE CELLS DO?
Scientists hope the stem cells developed in the lab will be able to repair the damaged cornea. But animal and human studies will have to be conducted to see if these are effective.

DIFFERENT TYPES OF RETINAL DISEASES
Diabetic retinopathy Macula degeneration Retinitis Pigmentosa Retinal Detachment Retinopathy of prematurity Leber congenital amaurosis THOUGH MOST BLINDNESS IN INDIA IS PREVENTABLE OR REVERSABLE, THE NUMBER OF PEOPLE WITH IRREVERSABLE BLINDNESS IS ON THE RISE.