A new camera could allow patients to skip the dreaded eye dilation during routine eye exams.

Researchers at the University of Illinois at Chicago College of Medicine, Massachusetts Eye and Ear and Harvard Medical School have developed a cheap, portable camera that can photograph the retina without the need for pupil-dilating eye drops.

“As residents seeing patients in the hospital, there are often times when we are not allowed to dilate patients — neurosurgery patients for example,” Dr. Bailey Shen, a second-year ophthalmology resident at the UIC College of Medicine, said in a statement. “Also, there are times when we find something abnormal in the back of the eye but it is not practical to wheel the patient all the way over to the outpatient eye clinic just for a photograph.”

The low-cost prototype can be carried in your pocket and can take pictures of the back of the eye without eye drops.

The camera is based on the Raspberry Pi 2 computer—a low-cost, single-board computer designed to teach children how to build and program computers.

The board hooks up to a small, inexpensive infrared camera and a dual infrared and white light emitting diode. The camera also includes a lens, a small display screen and several cables.

The camera first emits infrared light, which the iris—the muscle that controls the opening of the pupil—does not react to. The majority of retina cameras use white light, which is why pupil-dilating eye drops are required.

The infrared light is used to focus the camera on the retina, which can take a few seconds. Once focused, a quick flash of white light is delivered as the picture is taken.

Shen’s camera photos show the retina and its blood supply as well as the portion of the optic nerve that leads into the retina, which can reveal health issues that include diabetes, glaucoma and elevated pressure around the brain.

Dr. Shizuo Mukai, associate professor of ophthalmology at Harvard Medical School and a retina surgeon at Massachusetts Eye and Ear and co-author of the paper, said one of the benefits of the camera is how easy it is to build.

“This is an open-source device that is cheap and easy to build,” Mukai said in a statement. “We expect that others who build our camera will add their own improvements and innovations.”

Shen added that there is still work to be done on the camera.

“The device is currently just a prototype but it shows that it is possible to build a cheap camera capable of taking quality pictures of the retina without dilating eye drops,” Shen said. “It would be cool someday if this device or something similar was carried around in the white-coat pockets of every ophthalmology resident and used by physicians outside of ophthalmology as well.”