Abstract
Purpose :
This study is to develop and validate a high dynamic range (HDR) fundus camera for high-fidelity imaging over a wide field of view (FOV).
Methods :
Trans-palpebral illumination was used to construct a wide FOV fundus camera. Color efficiency balanced green (520 nm), and red (625 nm) illumination were employed for true-color fundus imaging. Three sequential fundus images with different illumination power controls were captured and served as low dynamic range (LDR) images to produce an HDR fundus image. All camera parameters were maintained the same for the sequential images and only illumination power was adjusted to acquire LDR fundus images. A fundus image was also taken with a commercial fundus camera Volk Pictor Plus for comparative assessment.
Results :
Without pupil dilation, a 140° eye angle (95° visual angle) FOV was achieved. The HDR fundus image (Fig. 1b) clearly shows the optic disc, which is saturated in the LDR fundus image with high power flash (Fig. 1a3), as well as details near the macula and the periphery, which are dim in the LDR fundus images with low and middle power flash (Fig. 1a, 1b)). A comparison of an enlarged HDR fundus image (Fig.1d) and the fundus image from Pictor (Fig.1c) shows the effectiveness of HDR imaging. The Pictor image has lower image contrast to differentiate vessels from the background due to red-dominated color and intensity inhomogeneity, while the small vessels can be differentiated in the HDR fundus image due to color balance and intensity homogeneity.
Conclusions :
The wide-field fundus imaging was achieved with trans-palpebral illumination up to a 140° eye angle FOV. Multi-intensity LDR fundus images and HDR processing enhanced the image contrast of wide-field fundus images, allowing better visualization of retinal features compared to traditional fundus images.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.