Approximately how many photoreceptors are there in the retina relative to the number of retinal ganglion cells?

• A. About one million
• B. About six million
• C. About one hundred twenty-five million
• D. About one and a half billion

Answer: (C)

Photoreceptors vastly outnumber the retinal ganglion cells. In a typical human retina there are about 125 million photoreceptors (rods and cones) but only about 1.2 million retinal ganglion cells to carry signals onward. That means photoreceptors outnumber the output neurons by roughly a hundred to one. This large difference is why most photoreceptors feed into relatively fewer ganglion cells, a setup that boosts sensitivity in dim light while still supporting decent detail in central vision. The number that states about 125 million photoreceptors matches the real scale of these cells, making it the best choice.