Japanese doctors have used thin sheets of tissue from people's cheeks repair damaged corneas . A team from Osaka University transplanted thin layers of cheek cells onto the eyes of four patients with a rare and painful eye condition,reports BBC online. Patients whose vision had been cloudy could see well afterwards,and the"new corneas"remained clear more than a year after the operation.  Doctors can also take cells from a healthy eye and grow them in a dish to produce a new cornea,or they can transplant corneas from donors . But these techniques may not work when both eyes are too badly damaged by accident or disease.  The team hope their work may help solve the problem and lead to other types of grow-your-own tissue transplants. The cornea is the clear layer of cells on the surface of the eye. It can be damaged by trauma or by a range of diseases.  The team worked with four patients who had a painful condition that causes cloudy corneas and dry eyes. Often the eye can regenerate  cornea cells but none of the four patients had this ability. The researchers took a 3 mm-wide square of tissue from inside the mouth(cheeks)and grew it into a thin layer in the lab. They used a special low temperature technique to separate a very thin sheet off each batch. They then laid that onto the patient's eye. The cell layers stuck onto the eye and developed into tissue that looked and acted like a healthy cornea.  However,long-term follow-up and experience with a large series of patients is needed to assess the benefits and risks this method. Yet,"it does offer the potential of treating severe eye diseases that are resistant to standard approaches,"said the head of the research,Kohji Nishida. If both eyes are too badly damaged,we can treat them   _  .
only by using mouth tissue by taking cells from a healthy eye and growing them in a dish by transplant healthy corneas from donors by none of the mentioned method
Question: Japanese doctors have used thin sheets of tissue from people's cheeks repair damaged corneas . A team from Osaka University transplanted thin layers of cheek cells onto the eyes of four patients with a rare and painful eye condition,reports BBC online. Patients whose vision had been cloudy could see well afterwards,and the"new corneas"remained clear more than a year after the operation.  Doctors can also take cells from a healthy eye and grow them in a dish to produce a new cornea,or they can transplant corneas from donors . But these techniques may not work when both eyes are too badly damaged by accident or disease.  The team hope their work may help solve the problem and lead to other types of grow-your-own tissue transplants. The cornea is the clear layer of cells on the surface of the eye. It can be damaged by trauma or by a range of diseases.  The team worked with four patients who had a painful condition that causes cloudy corneas and dry eyes. Often the eye can regenerate  cornea cells but none of the four patients had this ability. The researchers took a 3 mm-wide square of tissue from inside the mouth(cheeks)and grew it into a thin layer in the lab. They used a special low temperature technique to separate a very thin sheet off each batch. They then laid that onto the patient's eye. The cell layers stuck onto the eye and developed into tissue that looked and acted like a healthy cornea.  However,long-term follow-up and experience with a large series of patients is needed to assess the benefits and risks this method. Yet,"it does offer the potential of treating severe eye diseases that are resistant to standard approaches,"said the head of the research,Kohji Nishida. If both eyes are too badly damaged,we can treat them   _  .
A. only by using mouth tissue
B. by taking cells from a healthy eye and growing them in a dish
C. by transplant healthy corneas from donors
D. by none of the mentioned method
Answer: