Quantum biology of the retina

This review article discusses the role of quantum physics in biological systems with an emphasis on the retina.

The authors present a brief overview of quantum biology and some examples where quantum effects are associated with biological function, then go on to describe the process of phototransduction in the retina and the quantum properties during this process. Finally, they discuss the potential applications that arise from the quantum biology of the retina.

Recent evidence suggests that quantum features, such as entanglement, tunneling and coherence, have evolved in living systems, and are particularly evident in supersensitive light-harvesting systems, such as in photosynthesis and photoreceptors. They write that of particular interest to quantum optics is the development of single photon emitters and detectors.

The ability of the retina to be able to absorb and emit single photons and display different statistical properties in response to different photon statistics serves as a starting point for investigation and development of natural photoreceptors as photon detection or emission devices. Furthermore, the quantum processing of photoisomerization in different opsins occurs at remarkable rates and efficiency.

In the field of ophthalmology, bacteriorhodopsin remains under active research as a protein-based retinal prosthesis for patients suffering from retinal degenerative diseases. The proposed retinal implant mimics the light-absorbing capabilities of native human retina and generates a unidirectional proton gradient that is sufficient to stimulate the remaining functional retina.

It is envisaged that pathological retinal photorecptors may exhibit distinctive quantum signatures that could be exploited by novel diagnostic devices. Future research could investigate how the retina in different disease states may change its response.