Smartphones hold implications for retinal screening, beyond


The advent of smartphone devices and applications is transforming the practice of ophthalmology, especially in regard to ophthalmic diagnosis and monitoring.

Take-home message: The advent of smartphone devices and applications is transforming the practice of ophthalmology, especially in regard to ophthalmic diagnosis and monitoring. 

Reviewed by Mark S. Blumenkranz, MD, MMS

Stanford, CA-Devices and applications developed to work on smartphones are reducing the cost of ophthalmic diagnosis and monitoring, according to Mark S. Blumenkranz, MD, MMS. 

“We are entering into a new digital age of medicine that has the capacity to really transform how we practice ophthalmology,” said Dr. Blumenkranz, professor of ophthalmology, Stanford University, Stanford, CA.

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Until now, ophthalmic technology has been increasing in cost, he said.

He cited the example of a retinal camera for fundus photography that sold for $768 in 1925, the equivalent of $10,000 in 2015 dollars.

Improvements in technology have often meant increased prices as well as increased costs of care, said Dr. Blumenkranz, adding that fundus photography cameras today range from $40,000 to $100,000.

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By contrast, the cost of computers has decreased in real dollars even as their power has increased.

“Why doesn’t that translate into medicine?” Dr. Blumenkranz asked. “My argument is that effectively mobile health, or digital medicine is, for the first time, going to be a way to do that.”


Driving the change

Smartphones are driving this change, Dr. Blumenkranz said, citing estimates that more than 1 billion smartphones were shipped in 2014.

In addition, more than 2 billion will be in use by the end of 2016 worldwide.

“If you can use a smartphone and have access to the Internet, you have access to healthcare,” he said.

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The change is taking place across demographics, with more than 25% of Americans over 65 years of age expected to own a smartphone by the end of 2016.

Eventually, the majority of older Americans will old smartphones, Dr. Blumenkranz predicted.

“I don’t think that necessarily being tech-savvy will be necessary for taking advantage of technological health tools,” he said.

Digital age of medicine

Though smartphones are not designed for this purpose, attachments that take advantage of built-in cameras, powerful microprocessors, and Internet connectivity make them useful in diagnosis and monitoring of health conditions, Dr. Blumenkranz said.

“For a smartphone to measure visual acuity just requires software,” he said.

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Apple iPhones currently on the market have resolutions of 326 pixels per inch or more, he noted.

“These are not just toys,” Dr. Blumenkranz said. “These are anywhere from 10- to 20-fold more powerful than the best desktop computers of 20 years ago. So with appropriate hardware and software attachments they are capable of medical use.”

Smartphone applications used in medicine are proliferating, with 40 approved by the FDA in 2014, he said.

By 2018, there will be more than 15 million connected health-monitoring devices for smartphones-not just for ophthalmology, but also for diabetes, dermatology, and many other conditions, Dr. Blumenkranz said.


Adapters and attachments

Hardware attachments for smartphone use in ophthalmology include $300 adapters designed for fundus photography “that will take pretty high-quality photographs and be able to automatically transmit them to a central database,” he said.

For example, one system (Paxos Scope, DigiSight Technologies) consists of a spacer that holds an ophthalmic condenser lens with a small battery-supplemented light attached to a smartphone.

“It takes a picture roughly similar to fundus photography, not as good as the very best, but sufficiently clear to be able to make most fundus diagnoses,” said Dr. Blumenkranz, who has helped design the adapter.

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He noted recent research suggests that photographs acquired this way demonstrated 91% sensitivity and 98% specificity to detect moderate nonproliferative and worse diabetic retinopathy.

Additional manufacturers-including Peek Vision, Welch Allyn, and D-Eye-are selling or developing similar adapters, Dr. Blumenkranz said.

Another adapter can measure refractive error, he said.

“They will fit in your pocket, and certainly in a briefcase,” he said. “Some can do eye-tracking.”

Several companies are working on head-mounted displays similar to devices by Oculus, that can measure visual field, he added.

Alcon and Google are collaborating to develop smart contact lenses that could measure IOP or glucose, he said.

Smartphones can also be used to measure visual acuity by displaying charts in a variety of settings. These measurements have shown a high correlation with conventional measurements, Dr. Blumenkranz said.

Autorefractors and aberrometers are also becoming available as attachments to smartphones.

The technology could allow patients to monitor their own visual acuity at home, possibly adjusting the frequency of treatments for conditions, such as macular degeneration based on a larger data set than is available from office visits, Dr. Blumenkranz said.

“It’s a great tool for democratization of medicine,” he said. “It provides care to anybody regardless of socioeconomic status or healthcare coverage.”

People living in remote places, or who have difficulty going to medical exams, could use such apps and attachments for smartphones to create prescriptions for corrective lenses, which they could fill online, Dr. Blumenkranz said.

“So you can see how it could change the paradigm of care,” he said.


‘Powerful’ public health tool

In one project in Nepal, researchers demonstrated they could transmit fundus photographs from the field to central reading centers.

“You could be at the top of Mount Everest, take the visual acuity of a climber, take a photograph of his retina looking for high-altitude retinopathy or snow blindness, and-provided you had a link-all that data, including notes and conclusions, could be available to someone sitting at home in New York, Palo Alto, or Buenos Aires immediately.”

The technology could be used in equatorial South America to look for river blindness, or in Sub-Saharan Africa to look for leishmaniasis or trachoma, he said.

“It’s a very, very powerful public health tool, because instead of sending an ophthalmologist, you could send a student, a nurse, a technician, or a volunteer who could be trained in about an hour to take a fundus photograph,” he said.

Aiding medical research

Smartphones can also aid medical research, Dr. Blumenkranz said.

With or without attached devices, the devices can collect data and distribute it to cloud-based systems that aggregate it for analysis.

“In the past, when we wanted to develop approval for drugs or understand what’s going on in a population of patients, we chose representative samples of patients,” Dr. Blumenkranz said. “We couldn’t get everybody with a disease in a clinical trial.

“But clearly, if we have large numbers of people, it’s not outside the realm of possibility that a large percentage of patients might participate,” he said. “At that point, you have enough data to look at populations and subpopulations to see how well they did with a particular treatment.”



Dr. Blumenkranz acknowledged some challenges.

“There is potential for harm,” he said, outlining four “cardinal principles.”

  • Validation: Smartphone devices should be analyzed by physicians and undergo the same scrutiny required of any other medical device.

  • Regulatory compliance: Makers of smartphone devices need to meet Health Information Portability and Accountability Act (HIPAA) requirements and other relevant regulations, including those aimed to protect data security.

  • Privacy: Users have to be aware of the danger of the risks of sharing information publicly, for example through social media.

  • Integration. The data has to be readable across multiple platforms.

If the technology unfolds within these guidelines, physicians will be able to provide better care, payers can reduce their costs, and pharmaceutical companies can target their therapies, Dr. Blumenkranz predicted

“It’s a great opportunity for everybody inside the health care ecosystem to do better,” he said.



Mark S. Blumenkranz, MD, MMS


This article was adapted from Dr. Blumenkranz’s delivery of the Charles L. Schepens, MD Lecture at the 2015 meeting of the American Academy of Ophthalmology. Dr. Blumenkranz is a director and equity holder in DigiSight Technologies.

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