In animal experiments, researchers have achieved permanent transfer of a functioning gene to targeted tissues in the eye, in what they say is the first step toward gene therapy for glaucoma.

The experiments are reported in the online issue of Investigative Ophthalmology and Visual Science, by Dr. Nils Loewen and colleagues at the Mayo Clinic College of Medicine in Rochester, Minnesota.

The researchers injected viral vectors carrying marker genes into the eye chamber of 19 cats. One of the markers was a fluorescent green protein normally produced by jellyfish.

According to a press release from the Mayo Clinic, “When the vector reached the intended destination in the eyes of laboratory cats, the vector’s cargo gene produced the phosphorescent jellyfish protein in the cats’ eyes. Researchers knew they were successful because the cats’ eyes turned green when viewed with ultraviolet light at the targeted area.”

A single injection of the gene persisted in the targeted tissue for at least 10 months, the investigators found.

They believe their studies have provided “a basis for developing realistic disease models and administering glaucoma gene therapy.”

SOURCE: Investigative Ophthalmology and Visual Science, online October, 2004.