- 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
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 prototype retinal camera is affordable, portable and can take pictures of the back of the eye without the need for eye drops.’
The discovery is by a research team from the University of Illinois
at Chicago College of Medicine and Massachusetts Eye and Ear/Harvard Medical
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
"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
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
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
Drawbacks of Other
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.
"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
- 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