Researchers at the London School of Hygiene and Tropical Medicine believe the smartphone app can transform eye care for millions of people in remote parts of the world.
A trial on 233 people in Kenya showed that the Portable Eye Examination Kit (Peek) produced the same results as eye charts, researchers said.
The team in London, with colleagues in Scotland, modified a smartphone to develop a series of eye tests that could be used with little training and were easily portable.
It uses the camera's flash to illuminate the back of the eye to check for disease, 'BBC News' reported.
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The first clinical data from tests in Kenya, published in the journal JAMA Ophthalmology, show the vision test gives the same results as the rows of letters pinned to an optician's wall.
The phone is relatively cheap, costing around 300 pounds, while using bulky eye examination equipment costing in excess of 100,000 pounds.
"If we can detect people with visual impairment much earlier on then we have a much greater chance of increasing awareness and ensuring they have appropriate treatment.
"So something as simple as a vision test can be part of that journey," he said.