New Low-Cost Portable Retinal Camera Requires No Dilation of The Eyes

Highlights:

• Routine eye examinations usually require the use of pupil-dilating eye drops that can sting, take longer time to work and cause blurry vision.
• A new prototype, portable camera that can photograph the retina without the need for pupil-dilating eye drops, has been developed.
• The camera works by first emitting infrared light, which is used to focus the camera on the retina, and then to deliver white light as the picture is taken.

An inexpensive and portable camera that can photograph the retina, for routine eye-examination, without the need for pupil-dilating eye drops, has been developed.

The prototype of this nonmydriatic fundus camera is made out of simple parts mostly available online, and costs about $185. It measures 133mm X 91mm X 45mm and weighs 386 grams.

The discovery is by a research team from the University of Illinois at Chicago College of Medicine and Massachusetts Eye and Ear/Harvard Medical School.

To examine the retina, pupil-dilating eye drops are used routinely. These drops work by dilating the pupil and preventing the iris (which is the muscle that controls the opening of pupil) from constricting in response to light.

Some significant disadvantage of the drops include:

• Can sting
• Takes longer time (up to 30 minutes) to work
• Causes blurry vision
• Sensitivity to light for several hours afterwords

This can be an inconvenience for both the doctor and the patient.

"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 prototype camera can be carried in the pocket and can take pictures of the back of the eye without eye drops. The pictures can be shared with other doctors, or attached to the patient's medical record.

Retinal Camera- How it Works?

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

The board hooks up to a small, cheap infrared camera, and a dual infrared and white-light-emitting diode.

The rest of the camera is made up of a handful of other components like a lens, a small display screen and several cables.

The camera works by first emitting infrared light, which is used to focus the camera on the retina. This step can take up to a few seconds. The iris does not react to the infrared light.

Once the camera is focused, a quick flash of white light is delivered as the picture is taken.

The prototype camera photos show:

• The retina and its blood supply
• Portion of the optic nerve that leads into the retina
• Reveals health issues like diabetes, glaucoma and elevated pressure around the brain

Drawbacks of Other Traditional Retinal Cameras

Most table mounted, nonmydriatic fundus cameras use white light, which is why pupil-dilating eye drops are needed.

Though they use the same infrared/white light technique, most cameras are bulky, not portable and very expensive.

Conclusion

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

"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 findings in the Journal of Ophthalmology.

References:

1. Bailey Y. Shen, Shizuo Mukai. A Portable, Inexpensive, Nonmydriatic Fundus Camera Based on the Raspberry PiŪ Computer. Journal of Ophthalmology; (2017) DOI: 10.1155/2017/4526243

Source: Medindia