  Fundus photography is indispensable for clinical detection and management of
eye diseases. Limited image contrast and field of view (FOV) are common
limitations of conventional fundus cameras, making it difficult to detect
subtle abnormalities at the early stages of eye diseases. Further improvements
of image contrast and FOV coverage are important to improve early disease
detection and reliable treatment assessment. We report here a portable fundus
camera, with a wide FOV and high dynamic range (HDR) imaging capabilities.
Miniaturized indirect ophthalmoscopy illumination was employed to achieve the
portable design for nonmydriatic, widefield fundus photography. Orthogonal
polarization control was used to eliminate illumination reflectance artifact.
With independent power controls, three fundus images were sequentially acquired
and fused to achieve HDR function for local image contrast enhancement. A
101{\deg} eye-angle (67{\deg} visual-angle) snapshot FOV was achieved for
nonmydriatic fundus photography. The effective FOV can be readily expanded up
to 190{\deg} eye-angle (134{\deg} visual-angle) with the aid of a fixation
target, without the need of pharmacologic pupillary dilation. The effectiveness
of HDR imaging was validated with both normal healthy and pathologic eyes,
compared to a conventional fundus camera.
