Smartphone Apps for Vision in Developing Countries
New smartphone apps to test for visual acuity and eye diseases will be valuable in helping manage the outcomes for people in need, according to Professor Brien Holden, CEO of the Brien Holden Vision Institute.
“All of these devices will find their place in the fight against avoidable blindness and impaired vision. Such technologies can only help and the better and more affordable they become, the better they will be for screening,” Professor Holden told mivision.
One app soon to be released will cost just AU$2 and has been developed by researchers at the Massachusetts Institute of Technology.
Near Eye Tool for Refractive Assessment or ‘Netra’, (which means eye in Sanskrit) enables a person to check their vision acuity by looking into an eyepiece attached to the phone and using the phone’s buttons to move two lines on the screen until they appear as one. The number of clicks required to line up the images determines whether or not there is a vision problem and the results can be sent to an
eye doctor to make glasses.
One app soon to be released will cost just AU$2.
Another is the Peek, a “portable eye examination kit,” which consists of a mobile app and clip-on hardware, has been developed by scientists at the University of St. Andrews, the London School of Hygiene and Tropical Medicine and NHS Greater Glasgow and Clyde. According to the developers, it can be used to check glasses prescription, diagnose cataracts and examine the back of the eye for disease,
and it is currently being tested in Kenya.
Ophthalmologist Dr. Simon Chen said he is “delighted to see so much interest and research effort going into finding an affordable smartphone based solution to eye disease screening in the third world context.”
“Smartphone based visual acuity charts have been around for years and some have even been validated in published research studies which have demonstrated comparable visual acuity results when patients have been tested with smartphone based visual acuity charts compared to formal standard visual acuity charts.”
He cautioned that, “out in the field, it will be difficult to ensure standardisation of technical factors such as testing distance and background luminance which are important to maximise test accuracy.”
Dr. Chen said there is also potential for smartphones to pick up advanced cataracts by cataract screening using a combination of anterior segment images and red reflex assessment.
Dr. Chen said the NETRA, uses “a cheap piece of hardware that clips on to a smartphone to turn it into an autorefractor using the principles of a Shack-Hartmann sensor”. He described the system as: “interesting… but I don’t know how accurate and user friendly this is in practice yet”.
Similarly, he said it is hard to determine the quality of retinal images that the ‘Peek’ will deliver. “It is not clear from the app developers website (http://www.peekvision.org/features/) what additional hardware is being used to enable visualisation of the retina nor what quality of retinal image is obtained.
“The app appears to use a basic looking flat lens, so I would guess that only a very limited retinal image could be obtained which may enable screening for gross retinal and optic nerve disease such as advanced diabetic retinopathy or glaucoma,” said Dr. Chen.
“Before widespread implementation of an app such as this, it is clearly important that the sensitivity and specificity of the technology be rigorously assessed, which I believe is currently being done,” said Dr. Chen.
Professor Brien Holden said the major global issues surrounding delivery of vision screening and eye health services are, “access, affordability and availability of appropriate health personnel and systems for detection, diagnosis, treatment, management and prevention of disease and vision disorders.
“The most pressing of all these issues is the availability of local eye care professionals of all levels, working within the communities that are socially and economically disadvantaged. Sustainable, consistent, quality, available eye care as part of a comprehensive health care system, such as run by the Aboriginal Medical Services in Australia, can only be helped by accessible, useful, affordable advanced technology in the hands of the health care personnel,” added Professor Holden.