A US team has devised a smartphone system for capturing high quality photos of retinas to help diagnose eye diseases. The cheap and easy-to-use system could bring the advantages of affordable telemedicine to ophthalmology clinics.
The researchers, from Massachusetts Eye and Ear, a teaching hospital of Harvard Medical School, describe the new system and how they tested it in a recent online issue of Journal of Ophthalmology.
The study evaluated the smartphone system's ability to capture photographs of the "fundus," or retina, in human and rabbit eyes.
The equipment comprises a smartphone running an inexpensive app and instruments that can be found in any ophthalmic practice.
Taking photographs of the retina is an essential part of any ophthalmology practice. But current methods rely on fundus cameras that cost tens of thousands of dollars.
Previous studies using Apple's built-in camera app in the iPhone have concluded its video capture is not good enough, as it cannot independently control focus and exposure during filming, which produces glare and results in poor images.
But the system the Massachusetts Eye and Ear team used overcomes this by using an iPhone 4 or iPhone 5 with a more advanced smartphone app, called "Filmic pro," which allows for independent control of focus, exposure and light intensity during filming.
They tested the smartphone's ability to capture retinal images with a 20D lens, with or without a Koeppe lens - a special dome-shaped lens ophthalmologists use to get a direct view of certain parts of the eye, for instance the chambers that are involved in regulating pressure in the eye.
By using the coaxial light source of the phone, this system works as an indirect ophthalmoscope that creates a digital image of the fundus