Eight-month-old Sienna Ryan has septo-optic dysplasia, a congenital condition which affects just one in 10,000 newborns and stops the optic nerves developing properly.
Her family are trying to raise £25,000 to take her to Thailand for specialist stem cell treatment which is not available in this country.
Sienna, who lives with mum Danielle, 30, dad Ashley, 28, and brother Kye, 10, in Stanley, will have injections of synthetic hormones when she is older because her condition prevents the body from producing growth hormones.
But UK doctors said the effect on her vision was not treatable.
Mrs Ryan said: “Sienna will have been born with the condition and she was diagnosed when she was a couple of months old.
“She is registered blind. It can improve but not dramatically.”
There is no guarantee how successful the procedure in Thailand, which involves injecting stem cells to repair damaged nerves, would be. But the family are determined to give Sienna every chance they can to be able to see after researching the specialist treatment.
Mrs Ryan said: “There can be no improvement or a drastic improvement. It’s not the same for every patient. But we think it’s worth a try.”
The family thanked an anonymous donor who gave £10,000.
They have also raised £1,000 already themselves.
But they still need around £15,000 and are planning to hold fundraising events to raise the money.
Mrs Ryan said: “There’s the cost of the treatment but also the trip over there and accommodation.”