Helthcare & Wellness
May 1, 2017
BEYOND THE EYE
A few years ago, going to a dentist for a check-up, was still a nightmare. The "almost" medieval procedures, used to take away our sleep for days. And the same used to happen when we had to make accurate ophthalmologic exams. This reality changed as the years went passing by.
We all have already passed through the process of mydriatic fundus photography. It is the process in which ophthalmologists can photograph the retina of the eye, in order to evaluate both ophthalmic and non-ophthalmic conditions of the eye globe. This is both useful to use in diagnosis such as glaucoma, ocular cataracts and even some diabetes symptoms.
Nowadays, this exam is performed with the use of pupil-dilating eye drops, which can cause much discomfort. Not only do they sting, but they also take about twenty minutes to work. Plus, afterwards, they leave the patients with blurry vision and light sensitivity for several hours.
Besides, non-ophthalmologists are not familiar with the use of this pharmacologic drops. It is also not advisable to use them in patients with critical neurologic diseases.
These pupil-dilating eye drops are essential to keep the pupil open and allow the ophthalmologist to see through the eye globe up to the retina. Without them, the iris muscle would reflexively close the pupil as soon as it was exposed to a strong light source, which is needed to see the retina.
There are already cameras which use infrared/white light approach. These cameras, however, are quite large and cost thousands of dollars. They are bulky devices and they are not easy to transport.
A new proposal
Recently, Drs. Bailey Shen and Shizuo Mukai, from the University of Illinois and Harvard Medical School, both in the United States, have developed a new compact camera which will allow the pupil-dilation eye drops to be left in the past.
Non-mydriatic fundus photography allows ophthalmologists and non-ophthalmologists for imaging of the retina and optic nerve without the use of pharmacologic dilation.
Though there are different ways in which it can be done, the most common method is to use infrared light, to which the pupil does not constrict, to focus on the fundus and then, quickly flash white light to capture the colour fundus photograph before the pupil constrict.
Since the eye does not perceive the infrared light used to focus the camera, non-mydriatic photography is more comfortable to the patient, even with the white flash, when compared to physical examination and the proper use of pupil-dilation eye drops.
The scientists took advantage of a current camera and light-emitting diode (LED) technology to create an affordable prototype, small enough to carry it in a white coat pocket.
This non-mydriatic fundus camera is based on the Raspberry Pi 2 model, a credit card-sized computer board, designed to easily interact with its environment, and the NoIR camera board (also from the Raspberry Pi Foundation, Caldecote, Cambridgeshire, UK).
The NoIR camera board is a 5-megapixel camera, similar to a regular smartphone camera, except that it is sensitive to infrared light and is fixed-focus. The scientists changed the focus of the NoIR camera from infinity to 8 cm by unscrewing the lens counterclockwise.
Both devices are then attached to a 10400 mAh lithium battery. The illumination of the retina is provided by a dual LED prototype which can either emit infrared light or white light.
"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. It would be cool if, someday, 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", remarked Dr. Bailey Shen.