After 2 years, the preliminary results of LCA (Leber congenital amaurosis) gene therapy are in [Aug 12, 2009].
This study is still ongoing at U of FL and UPenn (and other universities). The participants are a woman and two men between the ages of 21 and 24. After 12 months, the safety is maintained. More important is this:
"The tiny portions of the patients’ retinas that received gene therapy [RPE65] experienced restored function up to 1,000-fold during the day and 63,000-fold at night."
In other words, the patients have developed a preferential retinal locus at the injected (treated) area. The visual acuity will depend on the photoreceptor density, among other issues. And the field size will necessarily be limited to the locus. Still, it is a giant leap forward.
Let's hope this study continues to be successful.