Why rods and cones?

Rods comprise 95% of our retinal photoreceptors despite the predominance of cones in vision under bright conditions.

• Cones account for only 5% of retinal photoreceptors, primarily mediating vision in well-lit environments.
• Rods are capable of detecting the arrival of individual photons, enabling sensitivity in low-light conditions.
• The retina has mechanisms to process single-photon signals, which may offer advantages in dim lighting.
• Slow dark adaptation presents a drawback for scotopic (rod-mediated) vision.
• The evolution of cone and rod photoreceptors, along with the retina and camera-style eye, is summarized.

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