A new study by researchers at the Washington University School of Medicine in the United States and the University of Zagreb in Croatia recently revealed that the movement of cells in the lens of the eye is similar to the carnival game Penny Pusher. The study is entitled “The Penny Pusher: A Cellular Model of Lens Growth” and was published in the journal Investigative Ophthalmology & Visual Science (IOVS).
“If the size, shape or position of the eye is not carefully regulated, we simply will not see clearly,” said the study’s senior author Dr. Steven Bassnett in a news release. “However, the mechanisms that tightly control the growth of the eye remain largely unknown.” In fact, the mechanisms that define the number of cells in the eye’s lens, its size and shape are poorly understood.
In the study, researchers analyzed the dynamic relationship between the proliferative cell behavior in the epithelial layer and the growth of the macroscopic lens using rodent models. The team also monitored where on the surface of the eye’s lens the cells were multiplying.
Researchers found that cells were primarily proliferating in a narrow line on the surface of the lens, and as new cells were formed, they pushed the already existing ones towards the lens’ equator. Once cells reached the equator, they were pushed away from the surface into the center of the lens. This motion resembles the movement of coins in the Penny Pusher carnival game. In this game, the player adds coins to an elevated and moving platform that is covered with several other coins, so that the coins at the far edge eventually fall onto a lower platform and from this to a place where the player can collect the earned coins.
“We made a physical model of the lens equator using layers of pennies to simulate the division and migration of the lens cells. Our Penny Pusher model looked very similar to [the carnival game],” explained Dr. Bassnett.
The model provides not only a better understanding of the eye’s regulation mechanisms and how it maintains its shape vital for clear vision, but also suggests a possible mechanism for cataract development, a condition where the eye’s lens changes from crystal clear to cloudy causing a blurred vision.
The research team suggests that if a narrow line of cells is forming new cells on the surface of the lens, then those few cells may have a substantial impact on lens clarity. “We are currently examining whether mutations in the DNA of individual lens cells can be transmitted to large numbers of lens cells, potentially influencing the clarity of the tissue and resulting in cataract,” concluded Dr. Bassnett.