Innovative Imaging Technique Enhances Retina Examination by Allowing Digital Refocusing

Eye care professionals rely heavily on fundus imaging to detect critical eye conditions such as diabetic retinopathy, glaucoma, and age-related macular degeneration, which are leading causes of vision impairment worldwide. Traditionally, fundus cameras used for these exams are costly, require skilled operators to focus precisely, and are often challenging to use in underserved areas. To address these limitations, researchers from Johns Hopkins University, Boston University, and collaborators have developed a groundbreaking fundus imaging system that simplifies the process and reduces costs.

This new approach eliminates the need for mechanical focusing adjustments, a significant hurdle in traditional systems. Instead, it utilizes a special holographic diffuser that captures three-dimensional light information from the retina during imaging. This data enables computer algorithms to reconstruct and refocus images digitally after the capture, making the system more adaptable and user-friendly. The innovation was detailed in the journal Biophotonics Discovery, marking the first successful application of this technology in living human eyes.

The team modified a standard commercial fundus camera by replacing parts of its optics with the diffuser and a sensitive digital sensor. After calibration, the device could record retinal images in model eyes, and software could sharpen these images for clear visualization of features such as the optic disk, blood vessels, and macula—even with refractive errors ranging over ten diopters. This is achieved without moving any optical components, maintaining the system's simplicity and stability.

In tests involving human volunteers, the device successfully captured color images of the retina, demonstrating its ability to refocus across various refractive errors. Its resolution, while slightly lower than traditional cameras, remained stable and sufficient for clinical use. Because the system contains no moving parts and relies on digital refocusing, it promises to be an affordable, portable, and easy-to-operate solution for eye exams. Moreover, researchers see potential in integrating this technology with autorefractors, which measure prescription needs, to create a comprehensive, all-in-one eye assessment device. Such advancements could greatly expand access to eye care worldwide.

This novel technique holds significant promise for making retinal imaging more accessible and cost-effective, especially in regions lacking advanced medical infrastructure, ultimately contributing to earlier detection and treatment of sight-threatening diseases.

Source: https://medicalxpress.com/news/2025-09-imaging-approach-retina-exams-enabling.html