In a decision that illustrates how things at the Food and Drug Administration are evolving, an FDA advisory committee unanimously approved a gene therapy for an inherited disorder.

On a 16-0 vote, the Cellular, Tissue and Gene Therapies Advisory Committee voted to approve Philadelphia-based Spark Therapeutics (ONCE - Get Report) treatment for a rare progressive form of blindness that begins in children.

Gene therapy has long been regarded as a place that could deeply impact patient care, but the science has proven elusive with the landscape between theory and practice being marred by disappointments.

The committee hearing demonstrated how the FDA is putting more weight behind patient testimony, especially when those patients are children and teens accompanied by parents, and the stories are emotional. Time and again, the committee heard from patients who described seeing a world in a new way and their lives forever changed by receiving the gene therapy.

In recent months, the agency has been alternatively criticized for not moving fast enough to approve new drugs and therapies and praised for listening to patients and advocates at emotionally charged hearings. Last year, Sarepta Therapeutics (SRPT - Get Report) received an accelerated approval for Exondys 51, a treatment for a rare form of muscular dystrophy after children and their parents took over an advisory hearing.

The gene therapy developed by Spark, affects the RPE65-mutation associated retinal dystrophy, a condition caused by a defective gene that attacks retina cells. Spark's therapy is called voretigene neparvovec and is tied to a modified version of a harmless virus which transports a healthy version of the gene into the eye via injections.

Diseases impacting the retina linked to defects in the RPE gene generate a patient pool in the U.S. between 1,000 and 2,000. The condition usually causes total blindness, with about half the patients being blinded by age 16.

The study that prompted the FDA hearing included 29 patients ranging in age from 4 to 44. While none of the patients regained normal vision, 90% of those treated showed improved sight, especially at night or in dim light, which is an issue for patients with the genetic disorder.

While the therapy was shown to be safe, there were some issues associated with the injections which included an elevated pressure in the eye as well as infections that were serious enough to do permanent damage.

While the FDA is not obligated to follow the recommendation of the committee, in practice the agency usually accepts the vote and an approval follows. Sparks plans on rolling out the gene therapy under the name Luxturna and at this time a price for the therapy has not been revealed, though the company said it was already planning on aiding patients in obtaining the therapy.

An FDA decision on Luxturna is expected in January.

Nasdaq suspended trading in Spark shares due to the FDA hearing. Shares closed Oct. 11 at $86.20 and in after-hours trading following the hearing, shares rose to $91, jumping 5.5%.

In August, the FDA approved Kymriah, a cell-based gene therapy to treat patients up to the age of 25 suffering with acute lymphoblastic leukemia that has not responded to standard treatments or where the patients have relapsed. Kymriah was developed by Novartis AG (NVS - Get Report) .