A girl who nearly lost her sight to cataracts is to lay the foundation stone to a new paediatric eye hospital.
The International Children's Eye Centre at Moorfields Eye Hospital in London will be the world's largest paediatric clinical training and research centre.
Former Moorfields patient Rhiannon Willis, 12, will lay the stone. She has helped with fundraising and will read a poem she wrote about losing her sight.
The new hospital is expected to open to patients in autumn 2006.
'Curing disease'
Ian Balmer, Chief Executive of Moorfields, said: "Rhiannon and patients like her will benefit enormously from this centre, which will be the largest of its kind in the world.
"The building will be child-focused and designed to make the patient experience as easy and pleasant as possible.
"It will also contain a large research facility to help us find new ways of treating and curing the diseases which affect children and can lead to sight loss."
The ceremony will be attended by the new hospital's donors who have so far contributed £12m towards the appeal to fund it.
A further £1.5m is still required to complete the appeal.