WIDE-FIELD SMARTPHONE FUNDUS VIDEO CAMERA BASED ON MINIATURIZED INDIRECT OPHTHALMOSCOPY

Abstract

Purpose: This study is to develop a low-cost, easy-to-use, wide-field smartphone fundus video camera to enable affordable point-of-care examination and telemedicine.

Methods: The wide-field smartphone fundus camera is based on a unique design of miniaturized indirect ophthalmoscopy. For proof-of-concept prototype, we used a Samsung Galaxy S6 smartphone and all off-the-shelf components. A fiber coupled LED was used to deliver illumination light through a 1 mm micro mirror, which was conjugated to the subject pupil plane, for retinal illumination. A 60D ophthalmic lens was used to image the retina through the eye, and a plano-convex lens with 90 mm focal length was used to relay the retinal image to the smartphone camera.

Results: A totally wireless smartphone fundus camera was constructed, with a whole weight of 255 g. This device allowed both snapshot fundus photography and continuous video recording. 92° field of view (FOV) was achieved in single-shot images. Optic disc, macula, and retinal blood vasculatures can be clearly observed with image quality comparable to standard fundus camera.

Conclusion: Miniaturized indirect ophthalmoscopy enabled a low-cost, portable, wide-field smartphone fundus camera, which can foster telemedicine and clinical deployments of wide-field fundus photography for eye disease screening, diagnosis and treatment assessment.

Figure 1

(A) Optical layout of the smartphone fundus video camera. L1 is a 60D ophthalmic lens. L2 is relay lens with 90 mm focal length. L3 is the built-in camera lens. Solid light lines illustrate illumination light rays, and thin dashed lines show imaging light rays. (B) Schematic illustration of the optical fiber and micro mirror based light source. The center of the mirror is ~10 mm from the center of the camera sensor.

Figure 2

Representative photographs of the smartphone fundus video camera.

Figure 3

(A–C) Representative single-shot images captured from a 41 years old age subject. The subject has no reported eye diseases. (D) Montage of single-shot images in Figs. 3A–C. (E) Representative fundus image from the same subject collected with a clinical fundus camera (Zeiss, Cirrus Photo 800), which has a single-shot FOV of 45° external angle, corresponding to 67.5°. (F) Overlap of images of Fig. 3C and Fig. 3E for FOV comparison.