Capturing the 'Twitch': A Potential Breakthrough in Retinal Diagnostics

A team led by Nanyang Technological University in Singapore demonstrates a mechanical rod photoreceptor twitch in living eyes when rods detect light; the signal appears within milliseconds and could serve as a non-invasive biomarker of rod function for earlier disease detection.

Optoretinography—an optical method that measures light-induced changes in optical path length with high temporal resolution—resolved these fast, micron-scale mechanical events. Recordings were made in vivo in both human and rodent eyes, with responses localized to rod outer segments and rapid onset. The technique is non-invasive and sensitive to transient mechanical signals that conventional structural imaging misses.

Unlike standard functional retinal tests, this mechanical signal provides a direct mechanical readout of photoreceptor activity rather than an electrical or structural surrogate such as electroretinography or conventional OCT. The observed twitch represents retinal mechanotransduction, linking photon capture to immediate mechanical output and establishing the novelty of detecting mechanical photoreceptor responses in vivo.

Clinically, disorders with early rod involvement—age-related macular degeneration, retinitis pigmentosa, and night-vision disorders—could benefit because rod-specific mechanical signals may enable earlier functional detection. That promise requires larger, comparative validation to define sensitivity, specificity, and practical workflows for clinical use.