Why beetles don't need glasses

To understand why so many people need corrective lenses, Elke Buschbeck is looking at an unusual creature that Mother Nature endows with keen vision.

Buschbeck, a biology professor at the University of Cincinnati, is studying diving beetles, aquatic insects that begin life as world-class assassins. Buschbeck raises diving beetles in large aquaria in her biology lab where their predatory prowess is on display. Each beetle can hunt and devour as many as 800 mosquitoes during their voracious larval stage.

The National Science Foundation in August will award Buschbeck’s lab a $900,000 grant over four years to study the beetles for insights into our own visual development. The project demonstrates UC’s commitment to research as described in its strategic direction, Next Lives Here.

Cook is comparing the 12 eyes of diving beetles to the compound eyes of fruit flies. Their visual systems are not so different after all, she said.

“It was shocking that these eye types would have any relationship to the compound eye,” she said.

Buschbeck is studying the genetic mechanisms that allow beetles to maintain their vision while growing as much as 130 percent between molts, when they shed their exoskeleton, including their old eye lenses.

Likewise, beetles maintain their perfect vision regardless of environmental factors such as growing up in total darkness, which would render us virtually blind under similar circumstances, Buschbeck said.

“This is an active field of study. We know that vision itself helps to focus the eye correctly,” she said. “In invertebrates, this really hasn’t been addressed, probably because it’s not an easy thing to measure.”

The beetles are the size of an M&M and just as colorful — a warning of their toxicity to animals tempted to eat them. The larvae are tinier, still. To study eyes smaller than the dot over this i, Buschbeck and UC assistant professor Annette Stowasser, her former postdoctoral fellow, spent three years designing a custom micro-ophthalmoscope that can measure the visual acuity of beetles, spiders and flies.

The device can use a “water lens” to measure the refraction that occurs in water.

“The refractive index is higher in water than in air, so an image that would be focused in water would be unfocused in air,” she said.

The equipment can be adjusted to the half-micron, which is a necessity when trying to peer into the teeny red eyes of a fruit fly.

“It gets worse. To get the optical measurements right for a fruit fly, we have to measure one ommatidium or lens at a time,” she said.

Dr. Karl Golnik, a neuro-ophthalmologist at UC’s Gardner Neuroscience Institute, said refractive errors are the most common vision deficit in people. This includes shortsightedness, farsightedness and blurred vision called astigmatism.

“We don’t see with our eyes. We see with our brain,” Golnik said. “To have any vision your brain has to be working normally. The signals have to get from your eyes to your brain down your optic nerve.”

Children develop their vision essentially through practice as the brain develops, Golnik said.

Understanding how vision develops in a model system like diving beetles could help medical researchers understand aspects of human eye development. Golnik said researchers are trying to learn more about the genetic relationships of many visual deficits and diseases.

“If they could be discovered in an animal model, that could theoretically lead to a treatment for those things in utero,” Golnik said. “If you don’t do the research, you’ll never know.”

Buschbeck said basic research pushes the boundaries of the unknown, which can lead to unexpected discoveries.

“We’re at the core of understanding these fundamental questions. It’s unpredictable how we might one day benefit from basic research. That’s why it’s really important to do it,” she said.