Mitochondria Function As Microlenses

A study on ground squirrels shows, not only do mitochondria produce bioenergy in the cone-shaped photoreceptors in the retina of the eye, they also act as micro-lenses that redirect light to the tapering outer reaches of these cells where light is converted into electrical signals.

The finding provides a clearer picture of the evolution and physiology of vision and the retina’s illusive optical properties. Insights from the study could also help in the early detection of eye diseases.

Once light reaches the retina, it must pass through several neural layers to reach the outer segment of photoreceptors, where light’s physical energy is converted into neural signals through a process called phototransduction. Between the inner and outer segment of the cone photoreceptors lie a dense bundle of mitochondria that light must traverse to be transduced. Although it might appear these mitochondria pose an obstacle to the process of vision by either scattering or absorbing light, the current study shows they serve a unique function to facilitate vision.

The team investigated the role of mitochondria in cone photoreceptors in the 13-lined ground squirrel. The 13-lined ground squirrel’s retina comprises mostly cones, which detect color, unlike rod-shaped photoreceptors that help in seeing in low light.

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