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Retina Camera, No Dilating Required

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A portable inexpensive camera that can photograph the retina could replace the need for pupil-dilating eye drops.

Researchers at the University of Illinois at the Chicago College of Medicine and Massachusetts Eye and Ear/Harvard Medical School have created a prototype camera that is small enough to carry in a pocket; it can take pictures of the back of a patient’s eye that can then be shared with other doctors or attached to a medical record.

Dr. Bailey Shen, a resident in the department of ophthalmology and visual sciences in the UIC College of Medicine, has his retina photographed using a camera based in the Raspberry Pi 2 computer.
Dr. Bailey Shen, a resident in the department of ophthalmology and visual sciences in the UIC College of Medicine, has his retina photographed using a camera based in the Raspberry Pi 2 computer. Courtesy of Bailey Shen.

"As residents seeing patients in the hospital, there are often times when we are not allowed to dilate patients — neurosurgery patients for example," said Dr. Bailey Shen, a second-year ophthalmology resident at the UIC College of Medicine. "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 camera is based on the Raspberry Pi 2, 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 works by first emitting infrared light, to which the iris — the muscle that controls the opening of the pupil — does not react. Most retina cameras use white light, which is why pupil-dilating eye drops are needed.

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. Cameras exist that use this same infrared/white light technique, but they are bulky and often cost thousands of dollars. Made out of simple parts, mostly available online, Shen’s camera costs about $185.

Camera photos can show the retina and its blood supply, as well as the portion of the optic nerve that leads into the retina. It can also reveal health issues such as diabetes, glaucoma and elevated pressure around the brain.

"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."

Shen and his co-author, Dr. Shizuo Mukai, associate professor of ophthalmology at Harvard Medical School and a retina surgeon at Massachusetts Eye and Ear, describe their camera and provide a shopping list of parts, instructions for assembly, and the code needed to program the camera in the Journal of Ophthalmology (

May/Jun 2017
camerasUniversity of Illinois at the ChicagoCollege of MedicineMassachusetts Eye and EarHarvard Medical SchooleducationResearch & Technologyopticsinfrared camerasBiophotonicsShizuo MukaiimagingTest & MeasurementBioScan

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