For 23-year-old Susan Muthoni, the placenta recently restored sight in her right eye, which she lost after a chemistry experiment gone wrong in secondary school five years ago.

In January, she got stem cell eye surgery at the Laser Eye Clinic in Nairobi.

Through a transparent, perforated plastic shield that is strapped on her right eye, a white membrane that stretches on the eye is visible.

An amniotic membrane, from the placenta, that would help her eye heal faster without leaving scars was used. The amniotic membrane ensures regeneration of stem cells in the affected eye once the stem cells are transplanted.

CHEMICAL BURN

“Corneal stem cells offer nutrients to the cornea, the window of the eye through which rays of light pass. Stem cells form the junction of the white and black part of the cornea.

“Damage causes the cornea to become cloudy. To reverse the damage, stem cells can be transplanted,” said Dr Mukesh Joshi, the ophthalmologist who performed the surgery.

The chemical burn damaged Ms Muthoni’s cornea cells, and turned off the light.

“Amniotic membrane is used in eye surgery for surface reconstructive surgery. The membrane prevents the formation of scar tissue. The scars affect proper movement of the eyelids and movement of tears across the eye,” said Dr Joshi.

If the patient’s other eye is healthy, stem cells can be removed from it and transplanted into the affected eye.

There are thousands of stem cells that feed into the cornea, but about two per cent are needed for the transplant. In case both eyes are damaged, the stem cells are acquired from the eye of relative or family member based on tissue type match.

The cells are then multiplied on the amniotic membrane, then glued on to the eye with a special glue that does not affect the eyelids.

The area is then covered by a contact lens, and a shield is placed to protect the eye. The stem cells should start growing back in six weeks.

The membrane dissolves and the patient’s cornea starts clearing.

The amniotic membrane used on Muthoni was imported from the United States, where placentas are collected from consenting mothers, then preserved at appropriate temperatures.

FUTURE USE

In some countries, transport of live amniotic membrane is not permitted, so it is dried for future use, and later activated to create a conducive environment for transplanted eye stem cells to grow.

“From 600 cells, you will have 20,000 cells in six months, to give the cornea nutrition, which it was deprived off when it was cloudy,” said Dr Joshi.

Stem cell surgery is performed on patients with severe infections that affect the cornea, those whose corneal stem cells have suffered burns, or people suffering from an infection affecting the mucus membrane.

Transplants can also be done from donated eyes, and though there is an eye bank in Kenya, there are not enough donations.

“We need a specialised laboratory to grow stem cells.

“Unlike the eye bank where you need to collect the eye from someone who is dead, stem cells can be collected from live donors and grown, then used to treat partial or total damage of eye stem cells.

The stem cell surgery costs about Sh200,000.