An international research project, led by the Research Institute of the McGill University Health Centre (RI-MUHC) in Montreal, reported that the new oral medication is showing significant progress in restoring vision to patients with Leber congenital amaurosis (LCA).
Until now, this inherited retinal disease that causes visual impairment ranging from reduced vision to complete blindness, has remained untreatable.
"This is the first time that an oral drug has improved the visual function of blind patients with LCA," said the study's lead author, Dr Robert Koenekoop.
The study involved 14 participants from around the world with LCA ranging in age from 6 to 38 years old. Their blindness was caused by either mutations in the genes RPE65 or LRAT, leading to a serious defect in the retinoid cycle.
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The retinoid cycle is one of the most important cycles in the human retina because it produces a molecule called 11-cis retinal which has the special capacity to capture light and initiate vision.
Patients with RPE65 or LRAT mutations cannot produce this crucial molecule thus the retinal cells cannot create vision, and slowly die.
"We discovered that a certain portion of the retinal cells that were not working because of the lack of 11-cis retinal could be woken up," said Koenekoop.
"Contrary to what was previously thought, children with LCA and defects in RPE65 or LRAT are not born with dead retinal cells; the cells can simply go dormant, and they can remain dormant for years before they eventually die. The oral drug we tested awakened these cells and allowed patients to see," Koenekoop said.
Ten out of the 14 patients expanded their visual fields; others improved their visual acuity. The research team performed special brain scans of the visual cortex, which showed marked improvements in brain activities in patients who also improved in field size and acuity.