"Smartphone-based retinal imaging has moved well beyond the stage of a technical experiment," says Dr. Maximilian Wintergerst from the UKB Eye Clinic, who also conducts research at the University of Bonn. "Our analysis shows that it can already support selected screening and triage scenarios. At the same time, we wanted to clearly highlight where the evidence is robust and where important questions remain unanswered."

Bringing eye exams closer to people

In regions with limited ophthalmic infrastructure and few specialists, building comprehensive screening programs is difficult and expensive. Smartphone-based imaging could serve as a building block for new, decentralized models of care. According to the analysis, other health care professionals — not just eye doctors — can capture usable retinal images after appropriate training. Those images can then be transmitted via telemedicine to specialized centers for evaluation.

This kind of approach matters most for conditions that require regular screening of large population groups. Diabetic retinopathy is a prime example.

"The smartphone does not replace an ophthalmological examination," says lead author Raphael Lechtenboehmer from Wintergerst's research group. "Rather, it can help expand access to retinal imaging, identify affected individuals with abnormal findings at an early stage and refer them more effectively to specialized diagnostic and treatment services."

Wintergerst's group has developed and tested smartphone-based fundus photography approaches in several international projects.

Where AI could help

The combination of smartphone imaging and artificial intelligence could play an important role in the future. AI systems could assess image quality in real time, even as the image is being captured, and check whether the required area of the retina has been fully photographed. Automated selection of the best individual images from image sequences, the merging of multiple images, and computer-aided detection of pathological changes are all conceivable applications.

"Particularly in screening programs with large numbers of patients, such automated support could help ensure that limited personnel resources are deployed more effectively," says Wintergerst.

Significant open questions

The analysis is equally clear about the technology's limitations. Smartphone-based imaging systems differ considerably in image quality and field of view, and their compatibility varies across smartphone models. Questions of regulatory approval, light and device safety, data protection and cybersecurity remain unresolved.

"There has not yet been sufficient research into the conditions under which smartphone-based screening programs can be operated economically and sustainably in the long term, and whether they ultimately lead to improved care and better treatment outcomes," Wintergerst notes.

The authors therefore call for larger-scale implementation and cost-effectiveness studies, as well as minimum reporting standards for future research. They present their work not only as an assessment of the available technology but also as a practical guide for clinicians, researchers and health care decision-makers evaluating where smartphone-based retinal imaging can be meaningfully integrated into screening, telemedicine and referral systems.

A global effort

To assemble global expertise for the review, the Bonn team brought together experts from multiple regions of the world. "This work exemplifies how important international scientific collaboration is for addressing global challenges in ophthalmology," says Frank G. Holz, director of the Eye Clinic at the UKB and a member of the Cluster of Excellence ImmunoSensation3 at the University of Bonn.

For now, the message is measured: smartphone-based retinal imaging is ready for carefully selected tasks, not a wholesale replacement for the eye clinic. With standardized studies and clearer evidence on costs and outcomes, it could help close a significant gap in global eye care.