GUCY2D and retinitis pigmentosa 1: The success of the VN trials saw uptake of FST as an outcome measure in other clinical trials for IRDs, including subretinal hMERTK therapy for patients with advanced retinitis pigmentosa (RP) (NCT01482195) (ref. [14]), electronic retinal prosthesis for end-stage RP (NCT02720640) (ref. [15]), and intravitreal antisense oligonucleotide therapy in CEP290-LCA (LCA10; NCT03140969) (ref. [16, 17]).