Selecting Channelrhodopsin Constructs for Optimal Visual Restoration in Differing Light Conditions

Channelrhodopsin (ChR)-based optogenetics is one promising approach to restore vision in photoreceptor degenerative diseases such as retinitis pigmentosa (RP) and age-related macular degeneration (AMD). Currently, a large number of ChRs from different alga species as well as engineered variants are available. They vary with their light response properties like peak sensitive wavelength (λ_max), current amplitude, and kinetics. Therefore, it is important to choose an appropriate ChR for practical applications, such as vision restoration. Here we describe a standard laboratory protocol for characterizing properties of ChRs in in vitro in human embryonic kidney (HEK) cells. Based on such characterization, we also discuss the criteria for selecting optimal ChRs for optogenetic vision restoration.