Abstract
Purpose:
To develop and evaluate the clinical utility of a smartphone-based portable fundus camera that can be used for wide-field imaging and recording of fundus pathologies at bedside.
Methods:
A polyurethane mount was designed and constructed to keep the camera module of a smartphone (iPhone 4S) aligned with the assistant mirror of an indirect ophthalmoscope (Keeler Inc., Broomall, PA). Pretesting was performed to determine the optimal lighting and focusing conditions for video and single-shot photography of the human fundus. Next, macular and peripheral images of various fundus pathologies were obtained using both a standard fundus camera (Zeiss FF450, Dublin, CA) and the smartphone-based camera. The clarity of the images, correct identification of the pathologies, and ease of obtaining and storing the fundus images were compared using 8 masked ophthalmologists. A 3D printable model of the camera mount was created with a 3D scanner.
Results:
High-quality imaging of the posterior pole and retinal periphery was achieved using the novel iPhone-adapted indirect ophthalmoscope. Best results were obtained when positioning the iPhone camera 0.5 cm from the assistant mirror and using medium intensity illumination (~0.6 mW cm-2 sr-1) from the indirect ophthalmoscope. When looking at the fundus images captured by the smartphone camera, survey participants accurately described the details of the fundus pathology 72% of the time. After viewing the corresponding standard fundus photos, only 28% of respondents changed their initial diagnosis correctly. The iPhone camera was easy to use and was able to image far peripheral lesions that were located beyond the capture range of the stationary fundus camera. It allowed documentation of a peripheral retinal lesion during dynamic depression. It also has the advantage of being considerably less expensive and more portable than other modalities.
Conclusions:
The Smartphone-adapted indirect ophthalmoscope can provide clinically useful imaging of the posterior pole and retinal periphery. This efficient, cost-effective, and portable imaging modality will allow rapid acquisition, storage, and transmission of fundus images in the pediatric population and in patients unable to sit for standard fundus photography. We believe it will be especially useful for documenting and monitoring the fundus changes in retinopathy of prematurity.