An experimental transplant of cells into the eyes of patients with failing sight improved vision in most of them, US researchers say.
The retinal cells, taken from aborted foetuses, were implanted into 10 people with retinitis pigmentosa and age-related macular degeneration.
The American Journal of Ophthalmology study found seven had better - although still seriously impaired - vision.
A UK expert said successful retinal transplant is science's "holy grail".
Retinitis pigmentosa and age-related macular degeneration (AMD) are the most common causes of blindness in old age, and involve the gradual and normally irreversible destruction of the cells on the eye's retina which receive light.
The technique used by the team at the University of Louisville, Kentucky, saw them implant the foetal retinal cells alongside cells which have the job of nourishing them, with the hope that the new cells would join forces with the existing retinal cells to improve overall vision.
Dr Norman Radtke, who led the project, said that sight tests showed no change in three of the 10 patients, but slight improvements in the rest.
In one case, this improvement was still present six years after the operation, even though the patient's other eye had continued to deteriorate.
However, the improvements were only modest, and eyesight was well short of normal vision.
Dr Radtke said: "What we have learned will help us to refine this method and obtain further evidence that retinal transplants may be a viable therapy for retinal degenerative disease."
Professor Pete Coffey, from the University College London Institute of Ophthalmology, said that the results did not suggest a major improvement in vision.
"I can't say that this is a success, except in the suggestion that the cells did not provoke an immune reaction in the recipient."
He said that no-one had yet managed a completely-successful transplant, which he described as the "holy grail" in the field.
He said that the use of foetal cells was also impractical, both for ethical reasons, and for sheer lack of supply.
"Unlike a stem cell line, every time you need new cells you need another foetus."