Experimental gene therapy restores night vision in patients with inherited blindness disorder

A Phase 2/3 clinical trial of a gene therapy called laruparetigene zovaparvovec demonstrated significant improvements in low-light vision for patients with X-linked retinitis pigmentosa, a rare inherited disorder primarily affecting males. The treatment, which delivers a functional copy of the RPGR gene to retinal cells, enabled 31 percent of high-dose recipients and 24 percent of low-dose recipients to read at least 15 letters more in low-light vision tests after 12 months. This represents the first pivotal treatment study for XLRP to achieve its primary endpoint with statistical significance.

X-linked retinitis pigmentosa primarily strikes males and represents one of the most severe forms of inherited retinal degeneration. The condition follows a predictable progression, with night vision problems emerging early—often during childhood—before advancing to tunnel vision and eventual legal blindness around middle age. The RPGR gene accounts for roughly seven out of every ten cases, making it the dominant genetic cause and therefore an ideal target for therapeutic intervention.

The VISTA trial's design compared treatment outcomes across dosage levels and an untreated control group, providing a rigorous baseline for measuring genuine therapeutic benefit. While improvements in low-light reading performance were substantial, results in other vision metrics showed more variable patterns. The surgical delivery method, which requires direct injection into the eye, accounted for the mild to moderate side effects observed, distinguishing complications of administration from the therapy's inherent safety profile.