She inherited a retinal disease called Leber Congenital Amaurosis.
It prevents the retina from processing light. She lived in a world of dark shadows.
So when researchers at Children's Hospital of Philadelphia suggested a risky gene transfer into her eyes, Manuella agreed.
"On the one hand, of course, I was frightened. On the other hand I felt I should try," said Manuella.
Back in 1985, the husband and wife team of eye surgeon, Dr. Al Maguire and gene therapy expert Dr. Jean Bennett came up with the idea of transplanting healthy genes into an unhealthy retina.
After years of research, Dr. Maguire performed the highly specialized surgery. Using a needle the width of two eyelashes, he introduced a virus into Manuella retina. The virus carried a healthy copy of the defective gene causing the blindness.
"It went perfectly and it was just a great relief to get it done," said Dr. Maguire.
Now two months later, letters Manuella could never see on an eye chart pop out at her.
"I could read more letters and I was very excited. It is quite strange," explains Manuella.
Her pupil prior to surgery had no response to light, but after surgery her pupil started to constrict like a normal eye.
"It could be, in historic terms, related to something like the first heart transplant or the first kidney transplant," explains Dr. Bennett.
Manuella is proud to be a pioneer on the frontier of hope.
"It will succeed not only for me, but for other people with visual problems. So they can hope," said Manuella.
Researchers believe this approach may one day be used for a broader spectrum of disorders, for diseases like retinitis pigmentosa and macular degeneration.