Yoko HIROHARA^1,2, Yoshitaka OKAWA¹, Toshifumi MIHASHI^1,2, Tatsuo YAMAGUCHI², Naoki NAKAZAWA², Yasuko TSURUGA², Hiroyuki AOKI², Naoyuki MAEDA³, Ichiro UCHIDA⁴, and Takashi FUJIKADO^1*

¹Department of Applied Visual Science, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
²Research Institute, Topcon Corporation, Tokyo 174-8580, Japan
³Department of Ophthalmology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
⁴Department of Anesthesiology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan

(Received September 7, 2006; Accepted March 8, 2007)

The purpose of this paper was to investigate the feasibility of a newly developed hyperspectral fundus imaging camera with a liquid crystal tunable filter. The intensities of different wavelengths of light transmitted through an artery, vein, and the area surrounding these vessels and reflected out were measured, and the differential spectral absorptions were analyzed. Measurements were made from 16 normal eyes and from two artificial capillaries. The ratios of absorption (ROA) of arteries to veins from 500 to 580 nm (range 1) and from 600 to 720 nm (range 2) were calculated. For all eyes, the ROA_range1 was larger than ROA_range2. The ROA obtained from the artificial capillary filled with blood saturated with oxygen or nitrogen was similar to that of simulated data of oxy- and deoxyhemoglobin extinction rate. Most ROAs of human eyes were lower than those of the simulated data and the artificial capillaries. Oxygen saturation analysis by hyperspectral fundus imaging of retinal vessels were qualitatively in agreement with the in vitro analysis or simulated values. However, further improvements are necessary to evaluate the oxygen saturation quantitatively in the retinal blood vessels.

Key words: hyperspectral imaging, absorption, optical density, oxygen saturation, liquid crystal wavelength tunable filter

^*E-mail address: fujikado@ophthal.med.osaka-u.ac.jp